Colletotrichum species and complexes: geographic distribution, host range and conservation status

Abstract

The taxonomy of the genus Colletotrichum has undergone tremendous changes over the last decade, with over 200 species being currently recognised and species complexes being informally used to cluster those species. Many of these species are important plant pathogens, some rather polyphagous and others host-specific, but several occur seldomly and some may in fact be ecologically endangered. Based mainly on literature from the past decade, in this work we review the occurrence, geographic distribution and host spectrum of currently recognised Colletotrichum species under phylogenetic, pathological/agronomic and ecological perspectives, providing a list arranged by Colletotrichum species and species complexes. A total of 257 species are listed and grouped into 15 species complexes. In this work we have recorded 1353 unique host species-Colletotrichum species association records from 720 hosts, with the Fabaceae as the family with higher number of hosts (52 host species) but with the Rosaceae as the family with the highest number of host species-Colletotrichum species association records (118 association records). According to occurrence data, 88 species are common in nature, 128 were considered as data deficient and 41 are threatened, some of which are likely extinct from nature and preserved only in culture collections. Several species are relevant plant pathogens, in some cases geographically confined and thus of potential quarantine relevance. Based on the major changes that occurred on Colletotrichum taxonomy over the last decade, this work provides a comprehensive overview of occurrence data of Colletotrichum species, compiling host range and geographical distribution, with relevance for plant pathology and conservation mycology. The current taxonomic framework in Colletotrichum is revealing numerous species but poses challenges to the employment of standard criteria for the evaluation of biological conservation of these fungi. We advocate that conservation mycology and taxonomy should find common routes simultaneously enabling the correct delimitation of species of Colletotrichum and the implementation of feasible criteria for the evaluation of conservation. The employment of new technologies, such whole genome sequencing (WGS), will help and support the description of new species and to gain a better understanding of the genetic bases of speciation processes.

Colletorichum taxonomy and importance

Many species belonging to the genus Colletotrichum are implicated in plant diseases, generally referred to as anthracnose, on a wide range of hosts, and these pathogens are characterised by a worldwide distribution and global relevance (Dean et al. 2012). Common hosts include many dicotyledonous plants such as strawberry, apple, citrus, and stone fruits, and major cereals such as maize and sorghum. Diseases on ferns and pines have also been reported. Anthracnose symptoms include dark necrotic lesions, which are oval or angular. Plant parts can be superficially affected at all stages of development, from seedlings to mature plants. Various Colletotrichum species are also important post-harvest pathogens due to their ability to undergo a non-pathogenic phase (Bailey and Jegger 1992). Colletotrichum species are characterised by a distinctive hemibiotrophic lifestyle (also known to occur in other fungal species, e.g. Magnaporthe). Fungi belonging to this genus initially infect through a brief biotrophic phase, associated with large intracellular primary hyphae. The fungus later switches to a necrotrophic phase, associated with narrower secondary hyphae that spread throughout the host tissue (De Silva et al. 2017b). Biomolecular processes that regulate this lifestyle have long been studied by the scientific community, especially those related to the switch from biotrophy to necrotrophy (O’Connell et al. 2012). Beside the economic impact of Colletotrichum species, this genus encompasses a wide diversity of important traits such as host range and host preference, mode of reproduction and differences in the strategy used to infect their hosts. In addition to being plant pathogens, Colletotrichum members can be plant endophyte and growth promoters, entomopathogens and opportunistic human pathogens. The genus contains a tremendous biological diversity within a group of closely related species, and this makes it a perfect model to study the molecular and genetic factors associated with biological traits.

The most recent formal description of the genus Colletotrichum is given by Jayawardena et al. (2020), providing, along with Marín-Felix et al. (2017), notes on morphology and cultural characteristics and information on standardised media and cultivation conditions. Colletotrichum was established in 1837, by Corda (Sutton 1992). Von Arx (1957) thoroughly revised the genus, reducing around 750 species to 11 taxa, which gradually increased. In 2000 the number of species was updated with morphological, cultural and pathogenicity studies and around 40 were accepted (Cannon et al. 2000). Colletotrichum species are mainly asexual, but some have a teleomorph that can be either homothallic or heterothallic. The MAT1-1/2 system in Colletotrichum species is not typical as that in most ascomycetes, as Colletotrichum fungi are capable of sexual reproduction while using only the MAT1-2-1 gene (Menat et al. 2016; Liang et al. 2021; Wilson et al. 2021). The genus Colletotrichum is the single genus in the Glomerellaceae family. Other members of the Glomerellales, namely in the families Australiascaceae, Reticulascaceae and Plectosphaerellaceae (Réblová et al. 2011; Giraldo and Crous 2019), are far less frequently reported, with Colletotrichum representing over 78% of the occurrences of Glomerellales recorded in GBIF database (www.gbif.org).

The advent of molecular systematics, at first based on ITS, and subsequently on multilocus sequence typing (MLST) approach, has accelerated the elucidation of phylogenetic relationships of Colletotrichum members. ITS is generally used to resolve species complexes within the genus (Jayawardena et al. 2016a; Marín-Felix et al. 2017). ITS is also sufficient to identify some species in the genus (e.g. C. graminicola and species in the gigasporum complex; Liu et al. 2014; Cuevas-Fernández et al. 2019). However, the delimitation of most Colletotrichum species requires additional use of a combination of sequences from some of the act, ApMat, apn2, cal, chs-1, gapdh, gs, his3, sod2 or tub2 genes (Jayawardena et al. 2016a, 2020, 2021; Marín-Felix et al. 2017). In fact, Colletotrichum, along with genera such as Alternaria, Aspergillus, Cladosporium, Fusarium and Penicillium, is recognised as an example of insufficient resolution of ITS for species delimitation (Lücking et al. 2020). However, the usefulness of such additional genes various strongly in different species complexes in the genus (Jayawardena et al. 2016a). The ApMat gene shows high resolution to distinguish species in the gloeosporioides complex, but it has been of little or no use in other complexes (Silva et al. 2012b; Sharma et al. 2015). In this study the phylogeny of Colletotrichum is constructed (Fig. 1) using the type strains of 252 species and five genetic loci (act, chs-1, gapdh, ITS and tub2 (Supplementary data 1, ‘sequences’ tab).

Fig. 1

Phylogeny of Colletotrichum species and complexes. Maximum-Likelihood Tree obtained by FastTree2 v2.1.10 (Price et al. 2010) reconstructed from act, chs-1, gapdh, ITS and tub2 sequence alignment of 253 reference isolates including the outgroup. The alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. The Markov chain Monte Carlo (MCMC) algorithm was performed to generate phylogenetic trees with Bayesian posterior probabilities for the alignment. Four MCMC chains were run simultaneously for random trees for 5,000,000 generations and sampled every 500 generations. The first 25% of trees were discarded as burn-in phase of each analysis and posterior probabilities were determined from the remaining trees. Bayesian posterior probability (obtained with MrBayes 3.2.6; Ronquist et al. 2012) and FastTree support values above 0.50/50 are reported next of the node; thicker branches represent node with BPP = 1.00 and ML = 100. The scale bar represents the number of expected substitutions per site. The tree is rooted with Monilochaetes infuscans. GenBank accession numbers are listed in Supplementary file 1. Information of each species such as host range, number of reported occurrences (O), number of reported host species, O/HS ratio, level of endanger and complexes are reported on the right

Accepted species of Colletotrichum and species complexes

As of June 2021, Index Fungorum lists 928 taxa in the genus Colletotrichum, 806 at the rank of species and the remaining 113 as diverse infra-specific taxa, mostly at the formae and varietas ranks. Colletotrichum lineola was the first species described in the genus, in 1831. The vast majority of Colletotrichum taxa (638 taxa) was described between 1888 and 1975 (Fig. 2), representing on average 7.3 taxa per year. One taxon per year was described on average in the 1976–2008 period, but since 2009 another 230 taxa were described (228 species; 18.3 taxa per year on average, peaking in 2012 with 58 taxa).

Fig. 2

Number of Colletotrichum species and infra-specific taxa recorded in Index Fungorum according to the year of publication since 1831 by decade (panel A) and since 2000 by year (panel B)

Literature published in the past 10 years (approximately 800 articles, of which 353 are Plant Disease Notes published in the journal Plant Disease) were scrutinised for occurrence data of Colletotrichum species. Occurrence data was only recorded when species names were unambiguous according to modern criteria, namely considering the literature that defined and delimited each complex: acutatum (Damm et al. 2012a); agaves (Bhunjun et al. 2021); boninense (Damm et al. 2012b); caudatum (Crouch 2014); dematium (Cannon et al. 2012); destructivum (Cannon et al. 2012); dracaenophilum (Damm et al. 2019); gigasporum (Liu et al. 2014); gloeosporioides (Weir et al. 2012); graminicola (Cannon et al. 2012); magnum (Damm et al. 2019); orbiculare (Cannon et al. 2012); orchidearum (Damm et al. 2019); spaethianum (Cannon et al. 2012); truncatum (Cannon et al. 2012). Previous check-lists were also considered (Jayawardena et al. 2016a, 2021; Marín-Felix et al. 2017). Fungal names were checked and used following Index Fungorum (www.indexfungorum.org). Similarly, plant names were checked and used according to Plants of the World Online (www.plantsoftheworldonline.org). Occurrences were recorded on a table, under the following parameters: fungal species; host species (and type of interaction, when known); location; date; reference. Location information was used for georeferencing, as previously described (Talhinhas et al. 2019) and occurrence maps were prepared using MapChart (https://mapchart.net).

Adapting as much as possible the criteria defined by Dahlberg and Mueller (2011) for Mycological Conservation and considering also Blackwell and Vega (2018), we considered as threatened the species identified once or very few times and that were identified either in conditions that impair conducting surveys (e.g., identified on hosts that are not clearly defined, such as hosts with no species given) or on hosts that are recurrently subject of surveys (e.g., chilli, citrus, coffee, mango, strawberry) from which other species of Colletotrichum are recorded instead. Other species seldomly reported were considered as ‘data deficient’. Species recorded from multiple hosts and/or locations were considered as common.

The acutatum species complex

Before the massive use of genetic information in taxonomy, Colletotrichum acutatum was considered as a single but morphologically and phylogenetically diverse species (Lardner et al. 1999), originally described from diseased tissues of Carica papaya, Capsicum frutescens and Delphinium ajacis in Australia by Simmonds (1965). Due to the high diversity of C. acutatum, several intra-specific groupings were established based on morphological, physiological, sexual, and molecular data (as revised by Sreenivasaprasad and Talhinhas 2005). Gradually, separate species were recognised as part of the acutatum complex, e.g. C. lupini (Nirenberg et al. 2002), C. phormii (Farr et al. 2006), C. simmondsii and C. fioriniae (Shivas and Tan 2009). The revision of the taxonomy performed by Damm et al. (2012a) was a landmark in the classification in which thirty-one species were accepted as member of the acutatum complex, of which 21 were newly described. To date, 41 species have been described (Fig. 3).

Fig. 3

Bayesian inference phylogenetic tree of the acutatum species complex and closely related singleton species. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

In phylogenetic terms (Fig. 3), the acutatum species complex can be divided in six clades with some degree of geographic structure. Whereas the lupini clade (comprising C. abcissum, C. costaricense, C. cuscutae, C. limetticola, C. lupini, C. melonis, C. paranaense and C. tamarilloi) shows clear evidence of neotropical origin (in spite of the global distribution of C. lupini), fungi in the nymphaeae clade (comprising C. brisbanense, C. cairnsense, C. carthami, C. chrysanthemi, C. cosmi, C. eriobotryae, C. guajavae, C. indonesiense, C. javanense, C. laticiphilum, C. miaoliense, C. nymphaeae, C. paxtonii, C. scovillei, C. simmondsii, C. sloanei, C. walleri and C. wanningense) occur mostly in Asia and Oceania (in spite of the global distribution of C. nymphaeae) and those in the godetiae clade (comprising C. acerbum, C. arboricola, C. australe, C. godetiae, C. johnstonii, C. kinghornii, C. lauri, C. phormii, C. pyricola, C. rhombiforme and C. salicis) are from multiple locations (with C. godetiae presenting global distribution). Two relevant but singleton clades are the acutatum and fioriniae clades, comprising C. acutatum and C. fioriniae respectively. Whereas they are both of global distribution, C. acutatum appears to have originated from Oceania (or perhaps from the Indian Ocean basin) and C. fioriniae from the Northern Hemisphere.

Members of the acutatum species complex have been associated with 171 plant species belonging to 129 genera (Supplementary data 1) and the vast majority of those species (90.9%) belong are dicots whereas only a small proportion are monocots and gymnosperms (5.3% and 1.6% respectively). Interestingly the acutatum complex is known to comprise the only Colletotrichum entomopathogenic species as C. fioriniae is pathogenic towards Fiorinia externa (elongate hemlock scale; Marcelino et al. 2008) and C. nymphaeae is pathogenic on Praelongorthezia praelonga (citrus orthezia; Mascarin et al. 2016).

Whereas most of the species within the complex are polyphagous, some show a strong specialisation towards one or a limited group of hosts; e.g. C. lupini is highly specialised toward Lupinus spp. (Talhinhas et al. 2016). Species from the acutatum complex have been suggested as a model system for the study of fungal evolution on a fine scale because of their different host range and host preference, reproduction mode, and various living strategy (Baroncelli et al. 2017). Several species in the complex present limited geographical distribution or host range but some, such as C. acutatum, C. fioriniae, C. godetiae and C. nymphaeae, are of global distribution and multiple hosts. Whereas C. godetiae and C. nymphaeae have a plethora of other species in their phylogenetic vicinity, both C. fioriniae and C. acutatum are not accompanied by any other species in their tree branches. Given the vast amount of data for organisms in any of these four clades, it is unlikely that such differences are due to sampling bias and thus such differences could suggest diverse reproduction strategies that may have shapped different patterns of evolution (wide diversification in the nymphaeae and godetiae clades, as well as in the lupini one, and low diversity in the acutatum and fioriniae clades).

Colletotrichum abscissum Pinho and O.L. Pereira, Persoonia 34: 237 (2015)

Colletotrichum abscissum is the causal agent of citrus Post-Bloom Fruit Drop (Crous et al. 2015). The fungus is restricted to Citrus spp. (Rutaceae) and to the American continent (Crous et al. 2015; Bragança et al. 2016; Silva et al. 2017a) and is thus a potential quarantine organism, namely in citrus producing areas.

Colletotrichum acerbum Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 43 (2012)

This species is based on a specimen collected from apple (Malus domestica, Rosaceae) in New Zealand in 1987 (Damm et al. 2012a). The fungus has not been detected thereafter, in spite of further research on apple bitter rot in New Zealand, as discussed by Damm et al. (2012a). This species could be endangered or even extinct from nature, particularly as other species of Colletotrichum inhabit the same ecosystem, causing apple bitter rot.

Colletotrichum acutatum J.H Simmonds, Qld. J. Agric. Anim. Sci. 22: 458 (1965)

Colletotrichum acutatum was originally described from Australia from diverse hosts and underwent several delimitations over time. Hosts harbouring C. acutatum sensu Damm et al. (2012a) include: in the Amaryllidaceae, Allium cepa (Lopes et al. 2021); in the Anacardiaceae, Mangifera indica and Pistacia vera (Shivas et al. 2016); in the Apocynaceae, Nerium oleander (Mosca et al. 2014); in the Caricaceae, Carica papaya (Damm et al. 2012a); in the Euphorbiaceae, Hevea brasiliensis (Hunupolagama et al. 2017); in the Fabaceae, Aspalathus linearis (Damm et al. 2012a) and Vicia faba (Shivas et al. 2016); in the Fagaceae, Castanea sativa (Gaffuri et al. 2017); in the Juglandaceae, Juglans regia (He et al. 2019); in the Myrtaceae, Acca sellowiana (Camele et al. 2018) and Psidium guajava (Liu et al. 2021b); in the Oleaceae, Olea europaea (Mosca et al. 2014; Chattaoui et al. 2016; Shivas et al. 2016; Iliadi et al. 2018; Talhinhas et al. 2018; Cara et al. 2021); in the Pinaceae, Pinus radiata (Damm et al. 2012a); in the Plumbaginaceae, Limonium sp. (Baroncelli et al. 2015); in the Proteaceae, Grevillea sp., Hakea sericea and Leucadendron sp. (Damm et al. 2012a); in the Punicaceae, Punica granatum (Mincuzzi et al. 2017); in the Ranunculaceae, Anemone sp. (Shivas et al. 2016); in the Rosaceae, Fragaria × ananassa (Damm et al. 2012a), Malus domestica (Shivas et al. 2016), Prunus dulcis (López-Moral et al. 2017) and Pyrus pyrifolia (Baroncelli et al. 2015); in the Rubiaceae, Coffea arabica (Damm et al. 2012a); in the Rutaceae, Boronia megastigma (Shivas et al. 2016), Citrus limon and C. sinensis (Guarnaccia et al. 2017); in the Solanaceae, Solanum lycopersicum (Liu et al. 2021b); in the Theaceae, Camellia sinensis (Chen et al. 2016a). Recorded mostly from Oceania and Africa in multiple hosts, Colletotrichum acutatum seems to be expanding to the Mediterranean region on several fruit crops, whereas it is virtually absent from the American continent (Supplementary data 2, panel A).

Colletotrichum arboricola M. Zapata, M.A. Palma and Piont., Persoonia 41: 353 (2018)

Colletotrichum arboricola was recorded from Fuchsia magellanica (Onagraceae) leaves in 2012 in Chile (Crous et al. 2018a) but the authors note that the fungus was subsequently detected in different arboreal hosts in the area. Although pathogenicity has not been confirmed, this fungus may cause concern to this widely used ornamental host, although its distribution and host range are still poorly known.

Colletotrichum australe Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 57 (2012)

There are no further records for this species besides the two isolates, collected from Trachycarpus fortunei (Arececeae) in Australia in 2011 and Hakea sp. (Proteaceae) in South Africa in 1998, originally used in the species description (Damm et al. 2012a). The current conservation status of this species requires further investigation.

Colletotrichum brisbanense Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 59 (2012)

There is a single isolate of C. brisbanense, collected from chilli (Capsicum annuum) in Australia in 1955 (Damm et al. 2012a). There are hundreds of reports of Colletotrichum on Capsicum spp. in the last decade, with over 30 different species of Colletotrichum associated, none of which corresponding to C. brisbanense, in spite of surveys conducted in Australia (Shivas et al. 2016). Colletotrichum brisbanense may well be extinct from nature.

Colletotrichum cairnsense D.D. De Silva, R. Shivas and P.W.J Taylor, Plant Pathol. 66: 254 (2017)

There is a single isolate of C. cairnsense, collected from chilli (Capsicum annuum) in Australia in 2015 (De Silva et al. 2017a). The current conservation status of this species is unknown and of concern.

Colletotrichum carthami (Fukui) S. Uematsu, Kageyama, Moriwaki and Toy. Sato, J. Gen. Plant Pathol. 78: 326 (2012)

Colletotrichum carthami is known from the Asteraceae Calendula officinalis, Carthamus tinctorius and Glebionis coronaria (= Chrysanthemum coronarium) from Italy, Japan and Korea (Damm et al. 2012a; Uematsu et al. 2012; Baroncelli et al. 2015; Sato et al. 2015). This fungus may be specific of Asteraceae.

Colletotrichum chrysanthemi (Hori) Sawada, Rep. Govt. Res. Inst. Dep. Agric., Formosa 85: 81 (1943)

Colletotrichum chrysanthemi is a pathogen of Asteraceae (Glebionis coronaria and Carthamus tinctorius), recorded from Europe and China (Damm et al. 2012a; Baroncelli et al. 2015). Further research may shed light on the relative importance of the different species of Colletotrichum associated with these hosts.

Colletotrichum cosmi Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 61 (2012)

The species Colletotrichum cosmi was described based on an isolate collected from Cosmos sp. (Asteraceae) in the Netherlands prior to 1973 (Damm et al. 2012a). Although Damm et al. (2012a) discusses the possibility of the fungus being present on Cosmos spp. in India, Korea and Japan, no other fungi have been so far assigned to this species, rendering the conservation status of this species of great concern.

Colletotrichum costaricense Damm, P. F. Cannon and Crous, Stud. Mycol. 73: 63 (2012)

The species Colletotrichum costaricense was described based on two isolates collected from berries and twigs of Coffea sp. (Rubiaceae) in Costa Rica prior to 1978 (Damm et al. 2012a). No other fungi have been assigned ever since to this species, rendering its conservation status of great concern, particularly as numerous species of Colletotrichum occur on coffee plants and despite numerous surveys conducted on this host.

Colletotrichum cuscutae Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 64 (2012)

The species Colletotrichum cuscutae was described based on a single isolate collected from Cuscuta sp. (Convolvulaceae) in Dominica in 1986 (Damm et al. 2012a). No other fungi have been assigned ever since to this species. Colletotrichum has been reported on Cuscuta from different parts of the world, but such isolates have not been characterised in modern terms. Only recently C. fioriniae was identified associated with Cuscuta sp. in the USA (Liu et al. 2021b). The conservation status of this species is thus of great concern.

Colletotrichum eriobotryae Damm and C.J. Huang, Mycol. Prog. 19: 367 (2020)

Colletotrichum eriobotryae was recently recorded as a pathogen of loquat (Eriobotrya japonica, Rosaceae) in China (Taiwan) (Damm et al. 2020). Although C. eriobotryae showed to be the prevalent pathogen in that study, several species of Colletotrichum have been associated to loquat anthracnose, suggesting further studies to ascertain the geographic distribution, host range and pathological relevance of C. eriobotryae.

Colletotrichum fioriniae (Marcelino & Gouli) Pennycook, Mycotaxon 132(1):150 (2017)

Colletotrichum fioriniae is a cosmopolitan fungus, found in all continents and in a wide range of host plants, but mostly occurring in temperate regions (Supplementary data 2, panel B). Colletotrichum fioriniae typically occurs along other Colletotrichum species associated to anthracnose symptoms, often being a less frequent and/or less virulent population. However, several reports consistently place C. fioriniae as the most frequently isolated fungus associated with apple bitter rot, namely in Europe and North America (Munda 2014; Munir et al. 2016; Nodet et al. 2016; Grammen et al. 2019). Colletotrichum fioriniae is known from: Actinidia sp. (Damm et al. 2012a) (Actinidiaceae); Allium cepa (Liu et al. 2021b) (Amaryllidaceae); Mangifera indica (Damm et al. 2012a), Pistacia vera (Lichtemberg et al. 2017) and Toxicodendron radicans (Kasson et al. 2014) (Anacardiaceae); Annona cherimola (Liu et al. 2021b) (Annonaceae); Apium graveolens (Liu et al. 2021b) (Apiaceae); Ilex verticillata (Lin et al. 2018a) and I. integra (Woo et al. 2021) (Aquifoliaceae); Berberis sp. (Damm et al. 2012a) and B. aquifolium (as Mahonia aquifolium) (Garibaldi et al. 2020; Guarnaccia et al. 2021) (Berberidaceae); Corylus avellana (Sezer et al. 2017) (Betulaceae); Cuscuta sp. (Liu et al. 2021b) (Convolvulaceae); Cucurbita sp. (Liu et al. 2021b) (Cucurbitaceae); Kalmia sp. (Damm et al. 2012a), Rhododendron yedoense (Sultana et al. 2018), Vaccinium corymbosum (Damm et al. 2012a; Eaton et al. 2021; Liu et al. 2021b), V. macrocarpon (Liu et al. 2021b) and V. myrtillus (Mosca et al. 2014) (Ericaceae); Vernicia montana (Zhang et al. 2021c) (Euphorbiaceae); Acacia acuminata (Shivas et al. 2016) (Fabaceae); Fagus sylvatica (Pszczółkowska et al. 2017) (Fagaceae); Myriophyllum spicatum (Damm et al. 2012a) (Haloragaceae); Juglans regia (Zhu et al. 2015; Varjas et al. 2019) (Juglandaceae); Origanum vulgare (Guarnaccia et al. 2019) and Salvia leucantha (Garibaldi et al. 2016c) (Lamiaceae); Persea americana (Damm et al. 2012a) (Lauraceae); Tulipa sp. (Damm et al. 2012a) (Liliaceae); Liriodendron tulipifera, Magnolia sp. (Damm et al. 2012a) and M. champaca (as Michelia champaca) (Zhang et al. 2018a) (Magnoliaceae); Ficus virens (Xue et al. 2017) and Morus alba (Xue et al. 2019) (Moraceae); Acca sellowiana (Crous et al. 2019a) (Myrtaceae); Olea europaea (Damm et al. 2012a; Mosca et al. 2014; Talhinhas et al. 2018; Moreira et al. 2021) (Oleaceae); Paeonia sp. (Liu et al. 2021b) (Paeoniaceae); Pinus radiata (Baroncelli et al. 2015) (Pinaceae); Piper nigrum (Damm et al. 2012a) (Piperaceae); Penstemon sp. (Damm et al. 2012a) (Plantaginaceae); Cyclamen sp. and Primula sp. (Damm et al. 2012a) (Primulaceae); Grevillea sp. (Damm et al. 2012a) (Proteaceae); Punica granatum (Xavier et al. 2019) (Punicaceae); Cydonia oblonga (Liu et al. 2021b), Fragaria × ananassa (Damm et al. 2012a; Baroncelli et al. 2015), Malus domestica (Damm et al. 2012a; Kou et al. 2014; Munda 2014; Nodet et al. 2016; Oo et al. 2018; Grammen et al. 2019), Prunus armeniaca (Eaton et al. 2021), P. dulcis (Liu et al. 2021b), P. persica (Lee et al. 2018), Pyrus communis (Da Lio et al. 2017; Fu et al. 2019; Pavlović et al. 2019), P. pyrifolia (Damm et al. 2012a; Fu et al. 2019; Pavlović et al. 2019; Liu et al. 2021b) and Rubus idaeus (Schoeneberg and Hu 2020) (Rosaceae); Coffea arabica (Damm et al. 2012a) (Rubiaceae); Acer negundo (Liu et al. 2021b) and Litchi chinensis (Ling et al. 2021) (Sapindaceae); Ailanthus altissima (Hyde et al. 2017) (Simaroubaceae); Capsicum annuum (Diao et al. 2017), Lycium barbarum (Liu et al. 2016a), L. chinense (Oo et al. 2016), Solanum lycopersicum (Damm et al. 2012a; Chechi et al. 2019) and S. melogena (Xu et al. 2018a) (Solanaceae); Camellia sinensis (Wang et al. 2016) (Theaceae); Parthenocissus sp. (Damm et al. 2012a) (Vitaceae); Fiorinia externa (elongate hemlock scale insect) (Marcelino et al. 2008).

Colletotrichum godetiae Neerg., Friesia 4: 72 (1950)

Colletotrichum godetiae is known from a large number of hosts and locations, with emphasis in Europe (Damm et al. 2012a; Jayawardena et al. 2016a) on almond, apple, peach, olive and strawberry (Supplementary data 2, panel C). It is known from: Sambucus nigra (Damm et al. 2012a) (Adoxaceae); Schinus molle (Damm et al. 2012a) (Anacardiaceae); Berberis aquifolium (as Mahonia aquifolium) (Damm et al. 2012a) (Berberidaceae); Cornus mas (Tóth et al. 2017) (Cornaceae); Aeschynomene indica (Damm et al. 2012a) (Fabaceae); Juglans regia (Damm et al. 2012a; Varjas et al. 2021) (Juglandaceae); Laurus nobilis (Damm et al. 2012a) and Persea americana (Hernández-Lauzardo et al. 2015) (Lauraceae); Olea europaea (Damm et al. 2012a; Mosca et al. 2014; Talhinhas et al. 2018) (Oleaceae); Clarkia hybrida (Damm et al. 2012a) (Onagraceae); Ugni molinae (Damm et al. 2012a) (Myrtaceae); Podocarpus sp. (Damm et al. 2012a) (Podocarpaceae); Helleborus sp. (Shivas et al. 2016) (Ranunculaceae); Ceanothus sp. (Damm et al. 2012a) (Rhamnaceae); Citrus aurantium (Damm et al. 2012a; Guarnaccia et al. 2017) (Rutaceae); Agrimonia eupatoria (Damm et al. 2012a), Cydonia oblonga (Živković et al. 2014), Eriobotrya japonica (Juárez-Vázquez et al. 2019), Fragaria × ananassa (Damm et al. 2012a; Grammen et al. 2019), Malus domestica (Baroncelli et al. 2014; Shivas et al. 2016; Wenneker et al. 2016; Grammen et al. 2019), Prunus avium (Damm et al. 2012a; Grammen et al. 2019), P. cerasus (Damm et al. 2012a), P. dulcis (Damm et al. 2012a; López-Moral et al. 2017; Liu et al. 2021b), Rubus glaucus (Afanador-Kafuri et al. 2014) and R. idaeus (Damm et al. 2012a) (Rosaceae); Solanum betaceum (Damm et al. 2012a) (Solanaceae); Parthenocissus sp. (Damm et al. 2012a) and Vitis vinifera (Damm et al. 2012a; Zapparata et al. 2017) (Vitaceae).

Colletotrichum guajavae Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 69 (2012)

Colletotrichum guajavae was designated based on an isolate collected from Psidium guajava (Myrtaceae) in India at an unknown date (Damm et al. 2012a). The species was subsequently identified as one of the causal agents of anthracnose on leaves of small cardamom (Elettaria cardamomum, Zingiberaceae) in India in 2011 (Chethana et al. 2016). The pathological status of C. guajavae and its geographical distribution requires further investigation. As causal agent of small cardamom anthracnose, the pathogen may be of quarantine relevance.

Colletotrichum indonesiense Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 71 (2012)

There is a single record of Colletotrichum indonesiense, obtained from leaf spots developing after herbicide treatment of an undesignated species of Eucalyptus (Myrtaceae) in Indonesia in 2008 (Damm et al. 2012a). Although Colletotrichum records on eucalypts are seldom, the circumstances of the discovery of C. indonesiense and the lack of additional records for this taxon raise serious concerns on its conservation status.

Colletotrichum javanense D.D. De Silva, P.W. Crous and P.W.J. Taylor, IMA Fungus 10: 8 (2019)

Colletotrichum javanense is based on a single isolate, obtained from a chilli (Capsicum annuum, Solanaceae) fruit in Indonesia in 2014 (De Silva et al. 2019). The high number of species of Colletotrichum occurring on Capsicum raises serious concerns on the conservation status of C. javanense, prompting for further surveys to ascertain its distribution and prevalence. As this fungus was shown to be highly virulent to chilli (De Silva et al. 2019), it may turn out to become a fungus of quarantine relevance.

Colletotrichum johnstonii Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 72 (2012)

Colletotrichum johnstonii was described based on two isolates collected in New Zealand, from fruit rot in Citrus sp. and tomato (Solanum lycopersicum) in 1989 and 1990, respectively (Damm et al. 2012a). Recently Liu et al. (2021b) associated an additional fungus to this species, isolated from groundnut (Arachis hypogaea, Fabaceae), at an unknown location and date. No further occurrences of C. johnstonii have been reported which, along the large number of species of Colletotrichum known from each host, raises serious concern on the conservation status of this taxon.

Colletotrichum kinghornii Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 73 (2012)

Colletotrichum kinghornii, described based on a single isolate collected from Phormium tenax (Xanthorrhoeaceae) in the UK in 1935 (Damm et al. 2012a), has been recently identified on Ph. cookianum in New Zealand (Crous et al. 2021). The scarcity of records suggests that the fungus is rare, although the employment of the host plant as an ornamental raises caution of possible quarantine implications.

Colletotrichum kniphofiae Crous and Denman, Fungal Syst. Evol. 1: 180 (2018)

Colletotrichum kniphofiae was recently described based on an isolate collected from Kniphofia uvaria (Xanthorrhoeaceae) dead leaves in the UK in 2016 (Crous et al. 2018b). Nothing is known about its ecology or pathology and no other species of Colletotrichum have been reported from K. uvaria, although C. spaethianum has been reported from K. northiae (Sato et al. 2015). The conservation status of C. kniphofiae is therefore of great uncertainty.

Colletotrichum laticiphilum Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 74 (2012)

The species Colletotrichum laticiphilum was described to accommodate fungi isolated from anthracnose symptoms on rubber tree (Hevea brasiliensis, Euphorbiaceae) leaves in Colombia and India (Damm et al. 2012a). The fungus was subsequently identified in Sri Lanka in 2012 also associated to anthracnose of rubber tree (Hunupolagama et al. 2017), suggesting that this fungus may be host specific. Several species of Colletotrichum occur on rubber tree, prompting further studies to analyse the pathological relevance and conservation status of C. laticiphilum.

Colletotrichum lauri Jayawardena, Camporesi and K.D. Hyde, Fungal Divers. 87: 148 (2017)

The species Colletotrichum lauri was described to accommodate an isolate obtained from dead leaves of laurel (Laurus nobilis, Lauraceae) collected in Italy in 2015 (Hyde et al. 2017). There are no other reports of this fungus worldwide and there are other species of Colletotrichum reported from laurel, raising serious concern about the conservation status of C. lauri.

Colletotrichum limetticola (R.E. Clausen) Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 76 (2012)

The species Colletotrichum limetticola is based on fungi isolated from wither tip symptoms on sour lime (Citrus aurantiifolia, Rutaceae) in Cuba and the USA (Damm et al. 2012a), but such records are dated from the 1910s, and no further occurrences have been recorded ever since on citrus, although several species of Colletotrichum are known from these hosts. However, C. limetticola was recently found in Brazil causing Glomerella leaf spot on apples, showing low prevalence but high virulence (Moreira et al. 2019a). Both hosts are subject of numerous studies concerning the identification of Colletotrichum, hence the scarcity of records of C. limetticola raise concern on its conservation status.

Colletotrichum lupini (Bondar) Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 78 (2012)

Colletotrichum lupini is the lupin anthracnose pathogen, reported from different parts of the world (Supplementary data 2, panel D) on several species of Lupinus (Fabaceae), including L. albus, L. angustifolius, L. consentinii, L. hartwegii, L. luteus, L. mutabilis and L. polyphyllus (Talhinhas et al. 2016). It is thus a host-specific pathogen of global distribution and common occurrence, although it has been sporadically reported from other hosts.

Colletotrichum melonis Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 80 (2012)

The taxon Colletotrichum melonis was described to accommodate a fungus isolated from melon (Cucumis melo, Cucurbitaceae) in Brazil prior to 1984 (Damm et al. 2012a). Although there are no further reports of Colletotrichum melonis from melon, the fungus was subsequently reported from persimmon (Diospyros kaki, Ebenaceae) in Brazil (Carraro et al. 2019) and from apple (Malus domestica, Rosaceae) in Brazil and Uruguay (Alaniz et al. 2015; Bragança et al. 2016; Moreira et al. 2019a). Colletotrichum melonis seems to be common in Southeastern South America.

Colletotrichum miaoliense P.C. Chung & H.Y. Wu, in Chung, Wu, Wang, Hu, Ariyawansa, Hung, Tzean & Chung, Sci. Rep. 10(no. 14664): 6 (2020)

Colletotrichum miaoliense is known only from Taiwan, associated to strawberry anthracnose among several pathogens from other species of Colletotrichum (Chung et al. 2020). The conservation status of this fungus remains to be analysed.

Colletotrichum nymphaeae (Pass.) Aa, Neth. J. Plant Pathol., 84: 110 (1978)

Damm et al. (2012a) recognised Colletotrichum nymphaeae as a pathogen of Anemone sp. (Ranunculaceae), Capsicum sp. (Solanaceae), Fragaria × ananassa, Malus pumila and Photinia sp. (Rosaceae), Leucaena sp. and Phaseolus sp. (Fabaceae), Berberis aquifolium (= Mahonia aquifolium, Berberidaceae), Nuphar lutea and Nymphaea alba (Nymphaeaceae), Oenothera sp. (Onagraceae), Olea europaea (Oleaceae), Pelargonium graveolens (Geraniaceae) and Protea spp. (Proteaceae). The fungus was subsequently identified from: Actinidia arguta (Actinidiaceae) in Korea (Kim et al. 2018); Allium cepa (Amaryllidaceae) in Brazil (Lopes et al. 2021); Apium graveolens (Apiaceae) in Japan (Yamagishi et al. 2015); Camellia oleifera (Theaceae) in China (Li and Li 2020); Campanula rapunculoides (Campanulaceae) in Italy (Guarnaccia et al. 2021); Carya illinoinensis (Juglandaceae) in Brazil and China (Poletto et al. 2019; Zhang et al. 2019a); Citrus aurantifolia (as Colletotrichum citri; Damm et al. 2020) and Citrus limon (Rutaceae) in China and Australia respectively (Huang et al. 2013; Shivas et al. 2016); Cyclamen persicum (Primulaceae) in Italy (Mosca et al. 2014); Diospyros kaki (Ebenaceae) in Brazil and Korea (Carraro et al. 2019; Hassan et al. 2019a); Eriobotrya japonica (Rosaceae) in China (Wu et al. 2018); Hevea brasiliensis (Euphorbiaceae) in Sri Lanka (Hunupolagama et al. 2017); Ilex verticillata × I. serrata (Aquifoliaceae) in the USA (Lin et al. 2018a); Juglans regia (Juglandaceae) in Brazil (Savian et al. 2019); Malus domestica (Rosaceae) in Brazil, Korea and the USA (Velho et al. 2014b; Munir et al. 2016; Oo et al. 2018); Prunus persica and P. salicina (Rosaceae) in Brazil and Korea respectively (Chang et al. 2018a; Moreira et al. 2020); Psidium guajava (Myrtaceae) in Brazil (Bragança et al. 2016); Punica granatum (Lythraceae) in the USA (Xavier et al. 2019); Pyrus pyrifolia (Rosaceae) in Brazil (Moreira et al. 2019b); Robinia pseudoacacia (Fabaceae) in Japan (Yamagishi et al. 2016); Rubus corchorifolius (Rosaceae) in China (Wu et al. 2021); Solanum lycopersicum (Solanaceae) in the USA (Chechi et al. 2019); Vitis vinifera (Vitaceae) in China (Liu et al. 2016b); the citrus scale insect Praelongorthezia praelonga (Hemiptera: Ortheziidae) in Brazil as Colletotrichum nymphaeae var. entomophilum (Wynns et al. 2019). Thus, C. nymphaeae occurs on a vast list of important agricultural crops, often as the main causal agent of anthracnose (such as strawberry anthracnose). Whereas older reports were more frequent in the Old World, most reports from the 2010s decade are from America, suggesting a recent spread over this continent (Supplementary data 2, panel E).

Colletotrichum paranaense C.A.D. Bragança and Damm, Fungal Biol. 120: 555 (2016)

Colletotrichum paranaense is known from Brazil only, associated to anthracnose symptoms in apple (Malus domestica) and peach (Prunus persica) fruits, as well as from Caryocar brasiliense (Caryocaraceae) (Bragança et al. 2016). In a population study, C. paranaense was identified in several states in Brazil associated to apple Glomerella leaf spot disease, although not as the most frequent pathogen (Moreira et al. 2019a). Further surveys will clarify the geographical distribution of Colletotrichum paranaense, its pathological relevance to apple and other crops, as well as its conservation status.

Colletotrichum paxtonii Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 85 (2012)

The species Colletotrichum paxtonii is known only from a fungus obtained from Musa nana (Musaceae) in Saint Lucia in 1972 (Damm et al. 2012a). The inexistence of any further occurrences of this species, in spite of the widespread cultivation of banana, along with the frequent occurrence of other species of Colletotrichum in this host, suggests that C. paxtonii may be extinct from nature.

Colletotrichum phormii (Henn.) D.F. Farr and Rossman, Mycol. Res. 110: 1403 (2006)

Colletotrichum phormii occurs on New Zealand flax (Phormium tenax and Ph. colensoi, Xanthorrhoeaceae), being reported from Australia, New Zealand, South Africa, Germany, the Netherlands, UK and the USA (Supplementary data 2, panel F), with reports spanning from the late nineteenth century till contemporary times (Damm et al. 2012a; Serdani et al. 2013; Baroncelli et al. 2015; Shivas et al. 2016). Colletotrichum phormii seems to be the most common causal agent of New Zealand flax anthracnose and it appears to be a relatively common fungus on this host.

Colletotrichum pyricola Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 94 (2012)

Defined originally based on an isolate collected from a pear (Pyrus communis, Rosaceae) fruit rot in New Zealand in 1988 (Damm et al. 2012a), Colletotrichum pyricola was subsequently identified associated to leaf and tip dieback of Daphne odora (Thymelaeaceae) in Australia (although collected in 1983) (Shivas et al. 2016) and to leaf spots of Embothrium coccineum (Proteaceae) in Chile in 2015 (Zapata and Opazo 2017). Although reported from diverse hosts and locations, this fungus is rarely recorded, prompting further studies to better ascertain its conservation status.

Colletotrichum rhombiforme Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 95 (2012)

Colletotrichum rhombiforme was described based on two isolates, obtained from olive (Olea europaea, Oleaceae) in Portugal in 2003 (Talhinhas et al. 2005; Damm et al. 2012a) and from blueberry (Vaccinium macrocarpum, Ericaceae) in the USA (Damm et al. 2012a). The species was subsequently identified from apple (Malus domestica, Rosaceae) in Belgium in 2014 (Grammen et al. 2019) and in China in 2016 (Wu et al. 2017) and from Vaccinium dunalianum var. urophyllum in China (Wang et al. 2019b). Whereas this species seems widespread, the scarcity of its records spread through several hosts suggests that further surveys are needed to ascertain its distribution, pathological relevance and conservation status.

Colletotrichum roseum M. Zapata, M.A. Palma, M.J. Aninat and Piont., Persoonia 43: 354 (2019)

The species Colletotrichum roseum contains isolates obtained from Lapageria rosea (Philesiaceae) in Chile in 2018 (Crous et al. 2019a). The geographical distribution, pathological relevance and conservation status of Colletotrichum roseum remains to be clarified.

Colletotrichum salicis (Fuckel) Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 97 (2012)

The species Colletotrichum salicis contains fungi occurring on diverse hosts and regions, in higher latitudes than most other species of Colletotrichum (Supplementary data 2, panel G): Acer platanoides (Sapindaceae) in the USA (Damm et al. 2012a); Araucaria columnaris (as Araucaria excelsa, Araucariaceae) in the USA (Damm et al. 2012a); Fragaria × ananassa (Rosaceae) in Belgium and New Zealand (Damm et al. 2012a; Grammen et al. 2019); Malus domestica (Rosaceae) in Belgium, Germany and New Zealand (Damm et al. 2012a; Grammen et al. 2019); Populus × canadensis and P. nigra (Salicaceae) in the Netherlands and Iran respectively (Damm et al. 2012a; Khodaei et al. 2019); Pyrus pyrifolia (Rosaceae) in New Zealand (Damm et al. 2012a); Rhododendron sp. (Ericaceae) in Latvia (Damm et al. 2012a); Salix spp. (Salicaceae) in Australia, New Zealand, Japan, Poland, Germany, the Netherlands and UK (Damm et al. 2012a; Shivas et al. 2016; Okorski et al. 2018); Solanum lycopersicum (Solanaceae) in Germany (Damm et al. 2012a); Vaccinium corymbosum (Ericaceae) in Norway (Damm et al. 2012a). Although there are some recent reports of Colletotrichum salicis, most ocurrences are old, suggesting that this fungus may not be very common in present days.

Colletotrichum scovillei Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 100 (2012)

Colletotrichum scovillei is a species associated to chilli (Capsicum spp., Solanaceae) anthracnose. This species in known from Asia (China, Indonesia, Japan, Korea and Thailand; Damm et al. 2012a; Kanto et al. 2014; Zhao et al. 2016a; Oo et al. 2017; Huo et al. 2021), but also from Brazil (Caires et al. 2014) and the USA (Toporek and Keinath 2021) (Supplementary data 2, panel H). Recently it has been reported in China associated to anthracnose symptoms on banana (Musa acuminata, Musaceae) (Zhou et al. 2017), mango (Mangifera indica, Anacardicaceae) (Qin et al. 2019) and wampi (Clausena lansium, Rutaceae) (Lin et al. 2020), and from Brazil associated to to anthracnose symptoms on onion (Lopes et al. 2021). The host range of C. scovillei and the pathological relevance for crops other than chillies still need to be fully elucidated.

Colletotrichum simmondsii R.G. Shivas and Y.P. Tan, Fungal Divers. 39:119 (2009)

Colletotrichum simmondsii sensu Damm et al. (2012a) is a fungus recorded predominantly from Australia, on multiple hosts: Actinidia chinensis (Actinidiaceae); Averrhoa carambola (Oxalidaceae); Calothamnus quadrifidus (Myrtaceae); Capsicum annuum (Solanaceae); Carica papaya (Caricaceae); Citrus reticulata (Rutaceae); Cyclamen sp. (Primulaceae); Fragaria × ananassa (Rosaceae); Hevea brasiliensis (Euphorbiaceae); Litchi chinensis (Sapindaceae); Mandevilla sp. (Apocynaceae); Mangifera indica (Anacardiaceae); Murraya sp. (Rutaceae); Nephelium lappaceum (Sapindaceae); Protea cynaroides (Proteaceae); Prunus domestica (Rosaceae); Punica granatum (Punicaceae); Solanum betaceum and S. lycopersicum (Solanaceae); Vaccinium corymbosum (Ericaceae) (Damm et al. 2012a; Shivas et al. 2016; Guarnaccia et al. 2017; Hunupolagama et al. 2017; De Silva et al. 2017a; Xavier et al. 2019). Few occurrences of Colletotrichum simmondsii are recorded from countries other than Australia and even fewer are recent, whereas most of the recent reports of the fungus are from Australia, suggesting this species to be mostly geographically confined to this country (Supplementary data 2, panel I).

Colletotrichum sloanei Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 103 (2012)

Colletotrichum sloanei was described based on a fungus isolated from cacao (Theobroma cacao, Malvaceae) in Malaysia in 1994 (Damm et al. 2012a). It was subsequently isolated from lychi (Litchi chinensis, Sapindaceae) in Australia in 2003 (Shivas et al. 2016) and recently from apple (Malus domestica, Rosaceae) and guava (Psidium guajava, Myrtaceae) in Indonesia in 2019 (Zhafarina et al. 2021). Records of C. sloanei are scarce and dispersed which, along with the occurrence of several other species of Colletotrichum on its hosts, render its conservation status of concern.

Colletotrichum tamarilloi Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 105 (2012)

Colletotrichum tamarilloi is the causal agent of anthracnose on tamarillo (Solanum betaceum, Solanaceae), reported from Colombia and Ecuador (Damm et al. 2012a; Pardo-De la Hoz et al. 2016; Caicedo et al. 2017), although Pardo-De la Hoz et al. (2016) also reported this fungus from mango in Colombia, and recently Lopes et al. (2021) reported it from onion in Brazil (Supplementary data 2, panel J). Colletotrichum tamarilloi thus seems to be mostly a host specific fungus of common occurrence on its host, but disseminating in South America.

Colletotrichum walleri Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 106 (2012)

Colletotrichum walleri is only known from a single isolate, obtained from coffee (Coffea arabica) in Vietnam in an unknown date (Damm et al. 2012a). Several species of Colletotrichum are known from coffee and there are no further records attributable to C. walleri, raising serious concerns about the actual existence of this species in nature.

Colletotrichum wanningense X.R. Cao, H.Y. Che and D.Q. Luo, Plant Dis. 103: 117 (2019)

Colletotrichum wanningense was designated based on a single isolate obtained from an asymptomatic leaf of rubber tree (Hevea brasiliensis, Euphorbiaceae) in China in 2017 (Cao et al. 2019b). Considering the large number of species of Colletotrichum recorded from Hevea and the absence of any further records of Colletotrichum wanningense, concerns raise on the actual conservation status of this species, prompting further surveys to ascertain it presence in nature.

The Agaves species complex

Recently described (Bhunjun et al. 2021), the agaves species complex is a well-established monophyletic group of five species, Colletotrichum agaves, C. ledebouriae, C. neosansevieriae, C. euphorbiae and C. sansevieriae (Fig. 4), considered until recently as singletons (Jayawardena et al. 2016a; Marín-Felix et al. 2017). The species complex name comes from C. agaves that has been the first species of this group described (Farr et al. 2006). Among the species encompassed in this complex, three species (C. ledebouriae, C. neosansevieriae and C. euphorbiae) seem to be extremely rare as they have been reported only once in South Africa. Colletotrichum agaves has been reported in several geographic regions (Italy, Mexico, USA, Cuba, Jamaica, Haiti, El Salvador) but not in the past 15 years, while several records have reported C. sansevieriae in diverse regions of Asia and in the USA. Interestingly four of the species encompassed in this complex such as C. agaves, C. ledebouriae, C. neosansevieriae and C. sansevieriae have been reported only on hosts belonging to the Asparagaceae family (Liliopsida [monocot]; Asparagales) whereas only one testimony of C. euphorbiae on Euphorbia sp. (Magnoliopsida [eudicot], Euphorbiales, Euphorbiaceae) has been reported.

Fig. 4

Bayesian inference phylogenetic tree of the agaves species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum agaves Cavara, Fung. Long. Exsicc. 3: no. 100 (1892)

As reviewed by Farr et al. (2006), most reports of Colletotrichum agaves are from the first half of the twentieth century. The three most recent records are from 2002 in Mexico, from 1982 in the USA and from 1979 in the Netherlands on Agave spp. (Supplementary data 3, panel A). Other Colletotrichum spp. occur on the Agavaceae and the current conservation status of C. agaves is of concern.

Colletotrichum euphorbiae Damm and Crous, Persoonia 31: 203 (2013)

The only record of Colletotrichum euphorbiae is from leaves of an unspecified species of Euphorbia collected at the Kirstenbosch Botanical Garden in South Africa in 2012 (Crous et al. 2013). There is no information on the pathological status of this fungus neither on whether the host plant was present as part of the botanical collection or as a weed. Considering that Euphorbia is a vast genus and one of the most morphologically diverse in botany, the conservation status of C. euphorbiae can be considered of extreme concern.

Colletotrichum ledebouriae Crous and M.J. Wingf., Persoonia 36: 331 (2016)

There is a single record of Colletotrichum ledebouriae, obtained from Ledebouria floribunda (Asparagaceae) in 2014 in South Africa (Crous et al. 2016). There are no records of anthracnose on this host and no further records for C. ledebouriae, raising serious concerns about its conservation status.

Colletotrichum neosansevieriae Crous and N.A. van der Merwe, Persoonia 34: 221 (2015)

This species is known only from a single isolate, collected in South Africa from Sansevieria trifasciata (Asparagaceae) in 2014 (Crous et al. 2015). The absence of further records for this fungus and the occurrence of other species of Colletotrichum on Sansevieria raises serious concerns on the conservation status of C. neosansevieriae.

Colletotrichum sansevieriae Miho Nakam. and Ohzono, J. Gen. Plant Pathol. 72: 253 (2006)

Colletotrichum sansevieriae is reported from Sansevieria trifasciata (Asparagaceae) in Japan since 1997 (Nakamura et al. 2006), in Australia since 2008 (Aldaoud et al. 2011), in the USA since 2010 (Palmateer et al. 2012), in Korea since 2012 (Park et al. 2013), in Iran since 2015 (Karimi et al. 2017) and in Malaysia since 2015 (Kee et al. 2020) (Supplementary data 3, panel B). Colletotrichum sansevieriae seems to be common and to show a high host specificity.

The boninense species complex

As a species, Colletotrichum boninense was first described in 2003 associated with Crinum asiaticum (Amaryllidaceae) in Japan (Moriwaki et al. 2003). Historically C. boninense was described as a pathogen and endophyte of a wide range of plant hosts worldwide until 2012 when Damm and colleagues (Damm et al. 2012b) used an MLST approach on 86 strains previously identified as C. boninense and other related strains revealing 18 clades and describing 17 of those as novel species. Since the taxonomic revision and the description of what is now known as the boninense species complex, more species have been described. Currently boninense is the third largest complex of the genus encompassing 26 described species (Fig. 5). Among these, half have only been reported once, whereas others such as C. boninense and C. cymbidiicola have been reported several times. Inside this complex C. karsti is by far the most cosmopolitan and polyphagous species as it has been associated with more than 60 plant species worldwide. Like the acutatum and the gloeosporioides species complexes, the boninense complex includes highly polyphagous species as well as species that show a certain level of specialisation. For example, C. cymbidiicola has been reported on at least eight plant hosts belonging to different genera but all of them belonging to the Orchidaceae family (Liliopsida [monocot]; Orchidales). A geographic and host-range analysis of the phylogeny of the boninense species complex reveal that: fungi in the clade containing C. annellatum, C. camelliae-japonicae, C. citricola, C. chongqingense, C. karsti and C. phyllanthi occur mostly in Asia and Oceania (but C. karsti is of global distribution); those in the clade containing C. catinaense, C. limonicola and C. novae-zelandiae are associated with citrus in Mediterranean Europe and New Zealand; fungi in the clade containing C. beeveri, C. boninense, C. brassicicola, C. colombiense, C. cymbidiicola, C. doitungense, C. oncidii and C. torulosum occur mostly in Asia and Oceania, with the C. cymbidiicola—C. oncidii cluster specifically from orchids; the fungi in the clade containing C. brasiliense, C. condaoense, C. hippeastri and C. parsonsiae originate from multiple continents; the clade comprising C. constrictum and C. dacrycarpi, phylogenetically basal to the complex, contains fungi from New Zealand. This phylogeographic approach indicates a wider species diversity in Asia and Oceania, suggesting that the complex may have originated from there.

Fig. 5

Bayesian inference phylogenetic tree of the boninense species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act, cal and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum annellatum Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 6 (2012)

There is a single record for Colletotrichum annellatum, collected from Hevea brasiliensis leaves in Colombia in 2010, with unconfirmed pathogenicity (Damm et al. 2012b). The pathological relevance and ecological status of this species remains to be analysed.

Colletotrichum beeveri Damm, P.F. Cannon, Crous, P.R. Johnst and B. Weir, Stud. Mycol. 73: 9 (2012)

There is a single record for Colletotrichum beeveri, from Brachyglottis repanda (Asteraceae) in New Zealand in 2006, although sequence similarity suggests its occurrence as endophyte on Pleione bulbocodioides (Orchidaceae) in China and on Podocarpaceae in New Zealand (Damm et al. 2012b). The current conservation status of this species is therefore of concern.

Colletotrichum boninense Moriwaki, Toy. Sato and Tsukib., Mycoscience 44: 48 (2003)

Colletotrichum boninense is recorded from several hosts, often as endophyte, mostly in Asia and Oceania (Damm et al. 2012b) (Supplementary data 4, panel A), including Crinum asiaticum var. sinicum (Amaryllidaceae; Damm et al. 2012b), Tecomanthe speciosa (Bignoniaceae; Damm et al. 2012b), Vriesea imperialis (as Alcantarea imperialis) (Bromeliaceae; Meneses et al. 2019), Manihot esculenta (Euphorbiaceae; Hyde et al. 2018), Eucalyptus robusta (Myrtaceae; Zhang and Zhu 2018), Bletilla ochracea and Dendrobium sp. (Orchidaceae; Tao et al. 2013; Hyde et al. 2018), Dacrycarpus dacrydioides (Podocarpaceae; Damm et al. 2012b), Leucospermum sp. (Proteaceae; Damm et al. 2012b), Coptis chinensis (Ranunculaceae; Ding et al. 2020); Capsicum frutescens, Solanum betaceum and S. lycopersicum (Solanaceae; Damm et al. 2012b; Diao et al. 2013; Rashid et al. 2015), Fragaria × ananassa, Rosa chinensis and Rubus rosaefolius (Rosaceae; Bi et al. 2017b; Ding et al. 2021; Zheng et al. 2021a), Coffea arabica (Rubiaceae; Freitas et al. 2013), Citrus medica (Rutaceae; Guarnaccia et al. 2017) and Camellia sinensis (Theaceae; Liu et al. 2015b).

Colletotrichum brasiliense Damm, P.F. Cannon, Crous and Massola, Stud. Mycol. 73: 11 (2012)

A single isolate is known for Colletotrichum brasiliense, collected in Brazil in 2006 from Passiflora edulis fruits (Damm et al. 2012b). Additional species of Colletotrichum are known from passionfruit (Damm et al. 2012b), raising concern on the conservation status of C. brasiliense.

Colletotrichum brassicicola Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 14 (2012)

There are only two known isolates for this species, collected respectively in New Zealand on Brassica oleracea var. gemmifera in an unknown date prior to 1998 (Damm et al. 2012b) and in Colombia on Rubus glaucus in 2008 (Afanador-Kafuri et al. 2014). Both plant species host several other species of Colletotrichum, therefore the pathological relevance and conservation status of C. brassicicola remains to be clarified.

Colletotrichum camelliae-japonicae LW. Hou and L. Cai, Mycosphere 7: 1117 (2016)

Colletotrichum camelliae-japonicae was reported only once, in 2013, on Camellia japonica plants from Japan (Hou et al. 2016). The conservation status of this pathogen is unknown and of concern.

Colletotrichum catinaense Guarnaccia and Crous, Persoonia 39: 32 (2017)

This species is known from Citrus sinensis (fruit tear-stain) and C. reticulata (leaf lesion) collected in 2015 in Portugal and Italy (Guarnaccia et al. 2017). As several species of Colletotrichum are found on Citrus spp. (Huang et al. 2013; Ramos et al. 2016; Douanla-Meli and Unger 2017; Guarnaccia et al. 2017; Silva et al. 2017a; Uysal and Kurt 2019), the pathological relevance and conservation status of Colletotrichum catinaense need to be further investigated.

Colletotrichum chongqingense Y.J. Chen, Plant Dis. 105: 1474 (2021) (in press)

The species Colletotrichum chongqingense was described based on a single isolate associated to anthracnose symptoms on Camellia sinensis (Theaceae) leaves in China, isolated in 2017 (Wan et al. 2021). Considering the vast number of species of Colletotrichum known from tea plants, the pathological relevance and conservation status of C. chongqingense are much uncertain.

Colletotrichum citricola F. Huang, L. Cai, K.D. Hyde and Hong Y. Li, Fungal Divers. 61: 67 (2013)

Initially described as an endophyte of Citrus unchiu collected in 2012 in China (Huang et al. 2013), Colletotrichum citricola was subsequently isolated from anthracnose symptoms on leaves of Pyrus pyrifolia in 2015 in China (Fu et al. 2019) and from healthy Dendrobium sp. plants in Thailand (Ma et al. 2018). All three host plants harbor other species of Colletotrichum, rendering the pathologic relevance of C. citricola uncertain and its conservation status of concern.

Colletotrichum colombiense Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 16 (2012)

Colletotrichum colombiense is based on an isolate collected from Passiflora edulis in Colombia in 2010 (Damm et al. 2012b). Additional isolates obtained from Passiflora sp. in Colombia may also belong to C. colombiense, as discussed by Damm et al. (2012b). Nevertheless, given that there are several species of Colletotrichum occurring on Passiflora, the conservation status of C. colombiense is uncertain.

Colletotrichum condaoense Damm, Persoonia 40: 240 (2018)

Colletotrichum condaoense is based on an isolate collected from Ipomoea pes-caprae (Convolvulaceae) in Vietnam in 2012 (Crous et al. 2018c). No other species of Colletotrichum have been reported on this host species. The host is widespread in tropical coastal areas, suggesting that the conservation status of C. condaoense should be investigated.

Colletotrichum constrictum Damm, P.F. Cannon, Crous, P.R. Johnst and B. Weir, Stud. Mycol. 73: 17 (2012)

Colletotrichum constrictum is composed of two strains, collected in New Zealand in 1988 from diseased lemon (Citrus limon) and tamarillo (Solanum betaceum) fruits, and presumably also of strains collected from Passiflora edulis and P. mollissima also in New Zealand (Damm et al. 2012b). No new strains have been assigned to C. constrictum for over 30 years which, together with the fact that all hosts harbor several species of Colletotrichum, render the conservation status of the species of great concern.

Colletotrichum cymbidiicola Damm, P.F. Cannon, Crous, P.R. Johnst. and B. Weir, Stud. Mycol. 73: 19 (2012)

Colletotrichum cymbidiicola is known from Cymbidium (Orchidaceae) in Australia, New Zealand, Japan and India (Supplementary data 4, panel B) with endophytic behavior (Damm et al. 2012b), but also from the orchids Bulbophyllum hirtum, Callostylis bambusifolia, Coelogyne sp., Dendrobium fimbriatum, Liparis viridiflora, Oncidium sphacealatum and Pinalia amica in India causing anthracnose (Chowdappa et al. 2014). Considering the vast amount of species of Colletotrichum occurring on Orchidaceae, the conservation status of C. cymbidiicola prompts for caution.

Colletotrichum dacrycarpi Damm, P.F. Cannon, Crous, P.R. Johnst. and B. Weir, Stud. Mycol. 73: 19 (2012)

Colletotrichum dacrycarpi, a morphologically and phylogenetically atypical Colletotrichum species, is known only from a single isolate collected as an endophyte on a Dacrycarpus dacrydioides (Podocarpaceae) leaf in New Zealand in 2009 (Damm et al. 2012b). There are no other records of Colletotrichum on Dacrycarpus, stressing that the conservation status of C. dacrycarpi is of great concern.

Colletotrichum doitungense X.Y. Ma, K.D. Hyde and Jayawardena, MycoKeys 43: 23 (2018)

Colletotrichum doitungense is known from a single isolate collected epiphytically on Dendrobium sp. (Orchidaceae) in Thailand in 2013 (Ma et al. 2018). Considering the vast amount of species of Colletotrichum occurring on Orchidaceae, the conservation status of C. doitungense is of great concern.

Colletotrichum feijoicola Guarnaccia and Damm, Persoonia 42: 291 (2019)

Colletotrichum feijoicola has recently been reported based on a single isolate, collected from Acca sellowiana (Myrtaceae) leaf spots from the Azores islands (Portugal) in 2017 (Crous et al. 2019b). Considering that several species of Colletotrichum have been reported from Acca sellowiana, the conservation status of C. feijoicola is of concern.

Colletotrichum hippeastri Yan L. Yang, Zuo Y. Liu, K. D. Hyde and L. Cai, Fungal Divers. 39: 133 (2009)

The species Colletotrichum hippeastri was designated to accommodate fungi isolated from Hippeastrum (Amaryllidaceae) hosts in Brazil, China and the Netherlands (Damm et al. 2012b). Reports of anthracnose are scarce on Hippeastrum and no additional occurrences of C. hippeastri have been described, raising concern on the conservation status of this species.

Colletotrichum karsti Y.L. Yang, Zuo Y. Liu, K.D. Hyde and L. Cai, Cryptog. Mycol. 32: 241 (2011)

Damm et al. (2012b) recognised Colletotrichum karsti from a number of hosts and regions (Supplementary data 4, panel C), including Annona cherimola, Anthurium sp., Capsicum annuum, Carica papaya, Citrullus lanatus, Citrus spp., Clivia miniata, Coffea spp., Cucumis melo, Diospyros spp., Eucalyptus grandis, Eugenia uniflora, Gossypium hirsutum, Leucospermum sp., Lupinus albus, Malus sp., Mangifera indica, Musa sp., Pachira aquatica (as Bombax aquaticum), Passiflora edulis, Quercus salicifolia, Sclerocroton integerrimus, Solanum betaceum, S. lycopersicum, Stylosanthes spp., Synsepalum dulcificum, Theobroma cacao, Triticum sp., and Zamia obliqua, along with orchid species, from where it was initially described (Youlian et al. 2011). The species was subsequently identified on Alocasia macrorrhizos and Areca catechu (Araceae) in China (He et al. 2014; Cao et al. 2020), Bletilla ochracea (Orchidaceae) in China (Tao et al. 2013), Camellia spp. (Theaceae) in China and Italy (Schena et al. 2014; Wang et al. 2016; Jiang and Li 2018), Carissa macrocarpa (=C. grandiflora; Apocynaceae) in Spain (García-Lopez et al. 2021), Dendrobium nobile (Orchidaceae) in Mexico (Fernández-Herrera et al. 2020), Dracaena braunii (as D. sanderiana, Asparagaceae) in China (Li et al. 2018a), Elettaria cardamomum (Zingiberaceae) in India (Chethana et al. 2016), Fatsia japonica (Araliaceae) in China (Xu et al. 2021), Fragaria × ananassa in Brazil (Soares et al. 2021), Hevea brasiliensis (Euphorbiaceae) in China (Cai et al. 2016a), Hylocereus undatus (Cactaceae) in Brazil (Nascimento et al. 2019b), Litchi chinensis (Sapindaceae) in China (Zhao et al. 2021c), Malus domestica (Rosaceae) in Brazil and Uruguay (Velho et al. 2014a, 2015), cassava (Manihot esculenta, Euphorbiaceae) in China (Liu et al. 2019a), Morus alba (Moraceae) in China (Xue et al. 2019), Nandina domestica (Berberidaceae) in China (Li et al. 2018b), olive (Olea europaea, Oleaceae) in Italy (Schena et al. 2014), avocado (Persea americana, Lauraceae) in Israel and Mexico (Velázquez-del Valle et al. 2016; Sharma et al. 2017), Pistacia vera (Anacardiaceae) in Italy and the USA (Schena et al. 2014; Lichtemberg et al. 2017), Pyrus pyrifolia (Rosaceae) in China (Fu et al. 2019), Rubus glaucus (Rosaceae) in Colombia (Afanador-Kafuri et al. 2014), Taxus wallichiana (Taxaceae) in China (Xu et al. 2019), Vaccinium sp. (Ericaceae) in Brazil (Rios et al. 2015) and Vellozia gigantea (Velloziaceae) in Brazil (Ferreira et al. 2017). Colletotrichum karsti is thus a cosmopolitan fungus, inhabiting a vast array of plant hosts.

Colletotrichum limonicola Guarnaccia and Crous, Persoonia 39: 32 (2017)

Colletotrichum limonicola is known only from a single record, obtained from wither-tip twigs of lemon (Citrus limon, Rutaceae) in Malta in 2016 (Guarnaccia et al. 2017). Considering that there are numerous species of Colletotrichum occurring on citrus, the conservation status of C. limonicola is of great concern.

Colletotrichum novae-zelandiae Damm, P.F. Cannon, Crous, P.R. Johnst. and B. Weir, Stud. Mycol. 73: 25 (2012)

Colletotrichum novae-zelandiae is known only from three isolates collected in New Zealand from chilli (Capsicum annuum, Solanaceae) and grapefruit (Citrus sp., Rutaceae) fruits in 1990 and 1988 respectively (Johnston and Jones 1997; Damm et al. 2012b). There are numerous species of Colletotrichum reported from each of these hosts and there are no further occurrences of C. novae-zelandiae ever since despite recent surveys, suggesting great concern on its conservation status.

Colletotrichum oncidii Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 26 (2012)

Colletotrichum oncidii is only known from an unspecified species of Oncidium (Orchidaceae), collected in 2010 in Germany (Damm et al. 2012b). There are no further occurrences of this species and there are many other species of Colletotrichum occurring on Oncidium, raising serious concerns over the conservation status of C. oncidii and rendering very difficult the deployment of surveys to ascertain its conservation status.

Colletotrichum parsonsiae Damm, P.F. Cannon, Crous, P.R. Johnst. and B. Weir, Stud. Mycol. 73: 27 (2012)

There are two occurrences reported for Colletotrichum parsonsiae, as an endophyte on Parsonsia capsularis (Apocynaceae) leaves in New Zealand in 2009 (Damm et al. 2012b) and on healthy leaves of Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). There are numerous species of Colletotrichum known from Bletilla, whereas there are no other reports from Parsonsia. Considering the scarcity of reports of C. parsonsiae, its conservation status can be considered of concern.

Colletotrichum petchii Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 29 (2012)

Colletotrichum petchii occurs on Dracaena (Asparagaceae), being reported from D. aletriformis, D. brownii, D. fragrans and D. sanderiana, in Australia, China, Germany, Italy and the Netherlands (Damm et al. 2012b; Shivas et al. 2016). Although reports of C. petchii range from the late nineteenth century to current times, spanning different hosts and locations (Supplementary data 4, panel D), the identification of other species of Colletotrichum on Dracaena advise periodic surveying to ascertain the conservation status of this species.

Colletotrichum phyllanthi (H.S. Pai) Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 31 (2012)

Damm et al. (2012b) reported Colletotrichum phyllanthi based on a single, non-sporulating fungal culture, obtained in 1966 in India from leaf anthracnose on Phyllanthus acidus (Phyllanthaceae) and stressed the absence of any further reports of this fungus. Moreover, a different species, C. acidae, clustering in the truncatum complex, has been recently reported from Phyllanthus acidus (Samarakoon et al. 2018). However, recently C. phyllanthi was recorded to occur epiphytically on Carapichea ipecacuanha (Rubiaceae) in Brazil (Ferreira et al. 2020), prompting for further surveys to ascertain its distribution and hosts.

Colletotrichum torulosum Damm, P.F. Cannon, Crous, P.R. Johnst. and B. Weir, Stud. Mycol. 73: 32 (2012)

Colletotrichum torulosum is known only from two isolates obtained in New Zealand from passionfruit (Passiflora edulis, Passifloraceae) in 2000 and eggplant (Solanum melogena, Solanaceae) in 1990 (Damm et al. 2012b). It is possible that this species also occurs on Kunzea ericoides (Myrtaceae) in New Zealand (Joshee et al. 2009; Damm et al. 2012b). Nevertheless, each of these three hosts harbor other species of Colletotrichum which, along the prolonged absence of new records for this species, raises concerns on the conservation status of Colletotrichum torulosum.

Colletotrichum watphraense X.Y. Ma, K.D. Hyde and Jayawardena, MycoKeys 43: 35 (2018)

Colletotrichum watphraense was designated based on a single isolate obtained from healthy stems of an unspecified species of Dendrobium (Orchidaceae) in Thailand in 2013 (Ma et al. 2018). The occurrence of several species of Colletotrichum on Dendrobium, along with the absence of any further records of this fungus, raises serious concerns about the conservation status of C. watphraense.

The caudatum species complex

Colletotrichum caudatum was considered as one single species pathogenic of a broad range of warm-season grasses as traditional morphological approaches differentiate C. caudatum sensu lato from other Colletotrichum species by the presence of a unique filiform appendage at the apex of the conidium (Crouch 2014). However, multi-locus phylogenetic analyses reject the view of a single species and instead have shown that isolates from different hosts were mainly segregated into different lineages. Initially subdivided in five species pathogenic to grasses, the caudatum complex now includes eight species (Fig. 6), three of which described as endophyte of Bletilla ochracea (Orchidaceae) (Tao et al. 2013). Based on our knowledge, members of the caudatum complex have only been reported to be pathogenic or endophyte of monocot hosts. The caudatum species complex is a monophyletic group of species that fit within the graminicola species complex with which shares similar characteristics like the host specificity towards different lineages of monocot plants.

Fig. 6

Bayesian inference phylogenetic tree of the caudatum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, tub2, apn2 and sod2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum alcornii J.A. Crouch, IMA Fungus 5:27 (2014)

Colletotrichum alcornii is known from only two specimens, collected from Bothriochloa bladhii and Imperata cylindrica var. major (Poaceae) in close locations in Australia in 1972/73 (Crouch 2014; Shivas et al. 2016). The conservation status of this species is thus of concern.

Colletotrichum baltimorense J.A. Crouch, IMA Fungus 5: 27 (2014)

Colletotrichum baltimorense is known only from Sorghastrum nutans (Poaceae), collected from a single location in the USA in 2011 (Crouch 2014). The pathological status of this fungus to indiangrass requires investigation and its conservation status is of concern.

Colletotrichum caudatum (Peck ex Sacc.) Peck, Bull. N.Y. St. Mus. 131: 81 (1909)

Colletotrichum caudatum is known only from Sorghastrum nutans (Poaceae) in the USA. It was identified twice in different locations, the first in 1887 and the second in 2007 (Crouch 2014). The pathological status of this fungus to indiangrass requires investigation and its ecological status is of concern.

Colletotrichum caudisporum G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 149 (2013)

There is a single record for Colletotrichum caudisporum, obtained as an endophyte from Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). Considering that there are several species of Colletotrichum associated to orchids, the ecological status of C. caudisporum is of great concern.

Colletotrichum duyunense G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 149 (2013)

Colletotrichum duyunense is only known from a single isolate collected epiphytically from Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). Considering that there are several species of Colletotrichum associated to orchids, the ecological status of C. duyunense is of great concern.

Colletotrichum ochraceae G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 156 (2013)

The species Colletotrichum ochraceae was designated to accommodate two isolates identified as endophytes on Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). No further occurrences of this species have been reported and several species of Colletotrichum occur on Bletilla ochracea, rendering the conservation status of C. ochraceae of high concern.

Colletotrichum somersetense J.A. Crouch, IMA Fungus 5:27 (2014)

Colletotrichum somersetense is known only from Sorghastrum nutans (Poaceae) from the USA, collected in 2011 (Crouch 2014). There are no additional records for this fungus and there are other species of Colletotrichum recorded from this host, raising serious concerns about the conservation status of C. somersetense.

Colletotrichum zoysiae J.A. Crouch, IMA Fungus 5:27 (2014)

Colletotrichum zoysiae is known only from Zoysia tenuifolia (Poaceae) leaves, collected in Japan in 1998 (Crouch 2014). Although there are no other species of Colletotrichum reported from this host, the absence of any further records of C. zoysiae raises concern over its conservation status.

The dematium species complex

The dematium species complex was firstly introduced by Cannon et al. (2012) based on species designation assigned by Damm et al. (2009), as part of a study of Colletotrichum species with curved conidia. The type species of the genus, C. lineola, is part of this species complex (Damm et al. 2009). As defined initially by the authors, the dematium clade contained six species forming two clear and distinct subclades. However, the distinct separation in two clades pretty far from each other and the low support values based on the ITS sequences suggest that the two lineages are different complexes. In the past years the number of species in this complex has increased rapidly reaching 17 described lineages (Fig. 7). Geographically, members of this complex are typically origin from Europe or central Asia, several of which from Russia.

Fig. 7

Bayesian inference phylogenetic tree of the dematium species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Members of the dematium species complex have been associated with 33 plant species belonging to 31 genera belonging mainly to eudicots (27/31). Colletotrichum dematium has also been reported as capable of infecting human tissues such as cornea.

Colletotrichum anthrisci Damm, P.F. Cannon and Crous, Fungal Divers. 39: 56 (2009)

There is a single record for Colletotrichum anthrisci, collected from Anthriscus sylvestris (Apiaceae) dead stems in the Netherlands in 2009, with unconfirmed pathogenicity (Damm et al. 2009). The host plant is widespread in temperate regions. The pathological behavior and conservation status of this species remains to be analysed.

Colletotrichum circinans (Berk.) Voglino, Annali R. Accad. Agric. Torino 49: 175 (1907)

Besides being a pathogen of onion and other Allium spp., Colletotrichum circinans is also known from other hosts (Anthriscus sylvestris, Beta vulgaris and Viola hirta), in different parts of the world (Damm et al. 2009; Sato et al. 2015) (Supplementary data 5, panel A).

Colletotrichum dematium (Pers.) Grove, J. Bot., Lond. 56: 341 (1918)

Colletotrichum dematium is known from several plant hosts in all continents (Supplementary data 5, panel B), either as a pathogen, a saprobe or an endophyte (Damm et al. 2009; Jayawardena et al. 2016a), including reports as a human opportunistic pathogen (Valenzuela-Lopez et al. 2018; Buchta et al. 2019). Nevertheless, recent reports of C. dematium sensu Damm et al. (2009) are seldom [on Polygonatum odoratum (Asparagaceae) in Italy (Karimi et al. 2016), on Asparagus racemosus (Asparagaceae) and on Hemidesmus indicus (Apocynaceae) in India (Rather et al. 2018), on Lycopus lucidus (Lamiaceae) and on Polygonum aviculare (Polygonaceae) in China (Guan et al. 2016; Liu et al. 2016d) and on Armeria maritima (Plumbaginaceae) in Japan (Sato et al. 2015)], suggesting that the conservation status of C. dematium should be under survey.

Colletotrichum eryngiicola Jayaward., Bulgakov and K.D. Hyde, Cryptog. Mycol. 38: 101 (2017)

Colletotrichum eryngiicola is known from a single isolate collected from Eryngium campestre (Apiaceae) in Russia in 2016 (Buyck et al. 2017). An additional species (C. dematium) has also been reported from this host, albeit both reports are very scarce, suggesting that the conservation status of C. eryngiicola is of concern.

Colletotrichum fructi (F. Stevans and J.G. Hall) Sacc., Syll. fung. (Abellini) 22: 1201 (1913)

There are only two described occurrences of Colletotrichum fructi, both recorded in the USA on apple, in 1907 and 1937 (Damm et al. 2009). Given that several other species of Colletotrichum occur on apple and that many studies have been conducted on apple bitter rot pathogens worldwide, the conservation status of C. fructi is of great concern and this taxon may well be extinct from nature.

Colletotrichum hemerocallidis Yan L. Yang, Zuo Y. Liu, K.D. Hyde and L. Cai, Trop. Plant Pathol. 37: 170 (2012)

Colletotrichum hemerocallidis is known from two isolates collected from dead stalks of Hemerocallis fulva var. kwanso (Xanthorrhoeaceae) in two locations in China in 2008 (Yang et al. 2012b). Considering the lack of any further reports of this fungus and the occurrence of other species of Colletotrichum on Hemerocallis spp., the conservation status of this species is of concern.

Colletotrichum insertae Jayawardena, Bulgakov and K.D. Hyde, Fungal Divers. 80: 176 (2016)

Colletotrichum insertae is only known from Parthenocissus inserta (Vitaceae) in Russia, where it was collected in 2015 as a saprobe on dying twigs and leaves (Hyde el al. 2016). There are several species of Colletotrichum recorded from Parthenocissus, rendering the conservation status of C. insertae of serious concern.

Colletotrichum jinshuiense M. Fu and G.P. Wang, Persoonia 42: 1 (2019)

Colletotrichum jinshuiense is known only from Pyrus pyrifolia (Rosaceae) leaves, collected in China in 2016 (Fu et al. 2019). This single occurrence, along with the high number of species of Colletotrichum reported from pear, calls for concern on the conservation status of C. jinshuiense.

Colletotrichum kakiivorum H.Y. Jung and S.Y. Lee, Mycol. Prog. 17: 1113-1121 (2018)

Colletotrichum kakiivorum is known from two occurrences associated with leaf spots in persimmon (Diospyros kaki, Ebenaceae) in Korea in 2016 (Lee and Jung 2018). There are several species of Colletotrichum occurring on persimmon, including in Korea, rendering the conservation status of C. kakiivorum of concern.

Colletotrichum lineola Corda, in Sturm, Deutschl. Fl., 3 Abt. (Pilze Deutschl.) 3 (12): 41 (1831)

Colletotrichum lineola, the type species of the genus Colletotrichum, occurs as a pathogen or as a saprobe on a large number of host plants and locations (Jayawardena et al. 2016a). In a study on Colletotrichum spp. with curved conidia in Japan, Sato et al. (2015) found Colletotrichum lineola on Dianthus sp. and Saponaria officinalis (Caryophyllaceae), Helleborus niger (Ranunculaceae), Isotoma axillaris (Campanulaceae), Sanguisorba officinalis (Rosaceae), Taraxacum campylodes (Asteraceae) and Vigna angularis (Fabaceae). More recently, Guarnaccia et al. (2021) reported C. lineola from Campanula trachelium (Campanulaceae) in Italy. Colletotrichum lineola is thus a common fungus worldwide, but apparently with low host preference.

Colletotrichum menispermi Chethana, Jayawardena, Bulgakov and K.D. Hyde, Fungal Divers. 78: 80 (2016)

The species Colletotrichum menispermi was described based on an isolate obtained from dead twigs of Menispermum dauricum (Menispermaceae) in Russia in 2014 (Li et al. 2016c). There are no additional records for this fungus nor other reports of Colletotrichum from this host, indicating that the conservation status of this fungus is of serious concern.

Colletotrichum parthenocissicola Jayawardena, Bulgakov, Huanraleuk & K.D. Hyde Fungal Divers. 104: 1 (2020)

Colletotrichum parthenocissicola is known only from dying and dead twigs and petioles of Parthenocissus quinquefolia (Vitaceae) in Russia in 2016 (Yuan et al. 2020). The absence of additional records for this species and the occurrence of other species of Colletotrichum on Parthenocissus raises severe concerns about the conservation status of C. parthenocissicola.

Colletotrichum quinquefoliae Jayawardena, Bulgakov and K.D. Hyde, Fungal Divers. 78: 83 (2016)

Colletotrichum quinquefoliae is known only from dying and dead leafstalks, twigs and tendrils of Parthenocissus quinquefolia (Vitaceae) in Russia in 2014 (Li et al. 2016c). The absence of additional records for this species and the occurrence of other species of Colletotrichum on Parthenocissus raises severe concerns about the conservation status of C. quinquefoliae.

Colletotrichum sambucicola Jayawardena, Camporesi and K.D. Hyde, Fungal Divers. 83: 131 (2017)

There is a single fungus known from the species Colletotrichum sambucicola, isolated from a dead branch of Sambucus ebulus (Adoxaceae) in Italy in 2016 (Tibpromma et al. 2017). There are no further references to this species and there are other species of Colletotrichum identified from Sambucus, raising serious concerns about the conservation status of C. sambucicola.

Colletotrichum sedi Jayawardena, Bulgakov and K.D. Hyde, Fungal Divers. 72:27 (2015)

Colletotrichum sedi is known only from a single occurrence, obtained from an unspecified species of Sedum (Crassulaceae) in Russia in 2014 (Liu et al. 2015b). The absence of additional reports for this fungus and the occurrence of other species of Colletotrichum on Sedum raise severe concerns about the conservation status of C. sedi.

Colletotrichum sonchicola Jayawardena, Camporesi and K.D. Hyde, Phytotaxa 314: 55 (2017)

The species Colletotrichum sonchicola was described based on a single isolate collected from dead stems of an unspecified species of Sonchus (Asteraceae) in Italy in 2016 (Jayawardena et al. 2017). Although no further species of Colletotrichum are known to inhabit Sonchus, the absence of any further records for C. sonchicola raises serious concerns about its conservation status.

Colletotrichum spinaciae Ellis and Halst., J. Mycol. 6: 34 (1890)

Initially treated as a specific pathogen of spinach (Spinacea oleracea, Amaranthaceae), Colletotrichum spinaciae sensu Damm et al. (2009) is recognised as occurring also on Chenopodium album (Amaranthaceae), Portulaca oleracea (Portulacaceae) and Medicago sativa (Fabaceae) in Europe and North America. More recently the fungus was reported on spinach in Turkey and Australia (Kurt et al. 2016; Shivas et al. 2016) and on Medicago sativa in China (Wang et al. 2019c). Colletotrichum spinaciae thus seems to be a common fungus.

The destructivum species complex

The destructivum aggregate was firstly introduced by Cannon et al. (2012) as a monophyletic group of six important plant pathogenic species: Colletotrichum destructivum, C. fuscum, C. tabacum, C. linicola, C. higginsianum and Glomerella truncata. Two years later, Damm et al. (2014) described the destructivum species complex encompassing the six previously mentioned species (with G. truncata renamed as C. lentis) and 10 closely related ones. Nowadays the complex has a total of 20 species (Fig. 8) and among them C. destructivum, C. lini and C. higginsianum are the most common ones whereas the others are pretty rare.

Fig. 8

Bayesian inference phylogenetic tree of the destructivum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Members of the destructivum species complex have been associated with 49 plant species belonging to 41 genera; the vast majority of these (37/41, 90%) are eudicots. Beside the economic impact of these pathogens, the species belonging to the destructivum complex such as C. higginsianum are important model systems that have been successfully used to advance the knowledge of the molecular basis of plant pathogenicity (O’Connell et al. 2012; Bhadauria et al. 2019).

Colletotrichum americae-borealis Damm, Stud. Mycol. 79: 55 (2014)

Originally described on Medicago sativa from the USA (Damm et al. 2014), Colletotrichum americae-borealis has recently been recorded in Iran as a pathogen on Tragopogon graminifolius (Asteraceae), Convolvulus arvensis (Convolvulaceae), Heracleum persicum (Apiaceae) and Sorghum halepense (Poaceae) (Khodaei et al. 2019) and in China also on Medicago sativa (Kemei et al. 2021), suggesting a pluricontinental distribution and polyphagous behaviour.

Colletotrichum antirrhinicola Damm, Stud. Mycol. 79: 56 (2014)

There is a single record for Colletotrichum antirrhinicola, collected from snap dragon (Antirrhinum majus, Plantaginaceae) leaves in New Zealand in 1999, with unconfirmed pathogenicity (Damm et al. 2014). The host plant is of widespread use as an ornamental. The pathological behaviour and conservation status of this species remains to be analysed. Anthracnose, attributed to Colletotrichum pathogens, is a common disease of snap dragon, but most of the literature lacks recent reports that may establish a clear link between this disease and C. antirrhinicola. In 2011, Tomioka et al. (2011) analysed the causal agents of snapdragon anthracnose in Japan, but these fungi can be attributed to C. higginsianum.

Colletotrichum atractylodicola R.J. Zhou and H.J. Xu, Mycol. Prog. 17: 393 (2018)

There is a single record for Colletotrichum atractylodicola, collected from Atractylodes lancea (as A. chinensis, Asteraceae) in China in 2013 (Xu et al. 2018b). There are various species of Colletotrichum occurring on Atractylodes, rendering the pathological status of C. atractylodicola uncertain and its conservation status of concern.

Colletotrichum bryoniicola Damm, Stud. Mycol. 79: 57 (2014)

There are two isolates of Colletotrichum bryoniicola, collected from decaying leaves of Bryonia cretica subsp. dioica (Cucurbitaceae) in the Netherlands in 2001 (Damm et al. 2014) and from anthracnose symptoms on Salvia nemerosa (Lamiaceae) in Italy in 2018 (Guarnaccia et al. 2019). The pathological and conservation status of C. bryoniicola is uncertain and of concern.

Colletotrichum destructivum O’Gara, Mycologia 7: 38 (1915)

Colletotrichum destructivum is found as a pathogen on numerous botanical families, mostly dicotyledonous, throughout the world, being recurrently reported (Supplementary data 6, panel A). Hosts of C. destructivum include: Cynanchum atratum (Apocynaceae; Miao et al. 2017); Aster tataricus and Helianthus annuus (Asteraceae; Cong et al. 2018; Sun and Liang 2018); Echium italicum (Boraginaceae; Khodaei et al. 2019); Medicago sativa, M. scutellata and Trifolium spp. (Fabaceae; Damm et al. 2014; Shivas et al. 2016; Xue et al. 2018b); Ocimum basilicum and Thymus vulgaris (Lamiaceae; Mosca et al. 2014; Fu et al. 2015); Bletilla ochracea (Orchidaceae; Tao et al. 2013); Phragmites sp. (Poaceae; Damm et al. 2014); Rumex crispus (Polygonaceae; Liu et al. 2017b); Viola odorata (Violaceae; Katoch et al. 2017).

Colletotrichum fuscum Laubert, Gartenwelt 31: 675 (1927)

Colletotrichum fuscum is known from Germany and the Netherlands on several species of Digitalis (Plantaginaceae) and on an unspecified species of Heracleum (Apiaceae) (Damm et al. 2014). It was also recently reported from Italy on Coreopsis lanceolata (Asteraceae) (Guarnaccia et al. 2021). There are no other species of Colletotrichum recorded from Digitalis or Coreopsis and additional reports of anthracnose on these hosts suggest the presence of the fungus in Poland and the UK (Zimowska et al. 2016; Cannon 2019). The apparent host specificity and relatively narrow geographic distribution of C. fuscum recommend caution concerning its conservation status.

Colletotrichum higginsianum Sacc., Riv. Accad. Padova 33: 161 (1917)

Damm et al. (2014) described Colletotrichum higginsianum as a taxon of pathogens of Brassicaceae. Recent reports are scarce and refer to hosts other than Brassicaceae, namely Campanula sp. (Campanulaceae) in Iran (Khodaei et al. 2019) and Rumex acetosa (Polygonaceae) in China (Zhang et al. 2018b). These observations suggest that the current host range and geographical distribution of C. higginsianum should be further investigated (Supplementary data 6, panel B).

Colletotrichum lentis Damm, Stud. Mycol. 79: 65 (2014)

Colletotrichum lentis was designated by Damm et al. (2014) to accommodate fungi infecting lentil (Lens culinaris, Fabaceae) occurring in Canada and Romania. The fungus was subsequently reported from common vetch (Vicia sativa, Fabaceae) in China (Xu and Li 2015). This fungus seems to be host specific and is commonly found causing lentil anthracnose.

Colletotrichum lini (Westerd.) Tochinai, J. Coll. agric., Hokkaido Imp. Univ. 14(4): 176 (1926)

Colletotrichum lini is known from flax (Linum usitatissimum, Linaceae), alfalfa (Medicago sativa) and Trifolium spp. (Fabaceae), Raphanus raphanistrum (Brassicaceae) and Teucrium scorodonia (Lamiaceae) (Damm et al. 2014). Nevertheless, the fungus is infrequently reported, recommending surveys to ascertain its conservation status (Supplementary data 6, panel C).

Colletotrichum neorubicola Yu Li, J. Gao & L. P. Liu, Mycol. Prog. 19:947-955 (2020)

This species comprises isolates obtained from Rubus idaeus (Rosaceae) in 2013 in China causing leaf anthracnose (Liu et al. 2020c). No additional fungi have been added to this species and several species of Colletotrichum are known from Rubus spp., rendering the conservation status of C. neorubicola of concern.

Colletotrichum ocimi Damm, Stud. Mycol. 79: 70 (2014)

Colletotrichum ocimi is associated to anthracnose of basil (Ocimum basilicum, Lamiaceae), and has been reported from Italy (Damm et al. 2014; Guarnaccia et al. 2019; Cacciola et al. 2020) and Australia (Shivas et al. 2016). The knowledge on the geographic distribution of C. ocimi requires further investigation to ascertain its pathological relevance and ecological status.

Colletotrichum orchidis Jayaward., Camporesi and K.D. Hyde, Mycosphere 11: 305 (2020)

Colletotrichum orchidis is known from a single isolate obtained from an aerial stem of an unspecified species of Orchis (Orchidaceae) in Italy (Hyde et al. 2020b). There are no additional records of this fungus and there are many species of Colletotrichum reported from orchids, raising serious concerns on the conservation status of C. orchidis.

Colletotrichum panacicola Uyeda and S. Takim., Chosen Nokai-ho 14: 24 (1919)

Colletotrichum panacicola is associated to anthracnose on Panax ginseng (Araliaceae) in China, Japan, Korea and Russia (Choi et al. 2011; Damm et al. 2014). The fungus appears to be host specific and to occur in Eastern Asia.

Colletotrichum pisicola Damm, Stud. Mycol. 79: 71 (2014)

Colletotrichum pisicola is known from pea (Pisum sativum, Fabaceae) in America (Ecuador, Mexico, Puerto Rico and the USA) (Damm et al. 2014), but all reports are old. The lack of recent occurrences of C. pisicola raise serious concerns about its conservation status, suggesting that this taxon may no longer occur in nature.

Colletotrichum pleopeltidis Crous & Jol. Roux, Fungal Syst. Evol. 7:285 (2021)

Colletotrichum pleopeltidis is known only from a single occurrence on leaves of an unspecified species of the fern Pleopeltis, collected in 2015 in South Africa (Crous et al. 2021). There are no details regarding the lifestyle of this fungus and its conservation status is of concern.

Colletotrichum shisoi P. Gan, A. Tsushima, M. Kawaradani, Damm and K. Shirasu, Sci. Rep. 9: 13349 (2019)

Colletotrichum shisoi is known only from anthracnose symptoms in Perilla frutescens (Lamiaceae) in Japan, where it was collected in 2006 (Gan et al. 2019). There have been no additional reports of C. shisoi, raising serious concerns over the conservation status of this taxon.

Colletotrichum tabacum Böning, Prakt. Bl. Pflanzenbau Pflanzenschutz 10: 89 (1932)

Colletotrichum tabacum sensu Damm et al. (2014) is a species occurring on tobacco (Nicotiana spp., Solanaceae) as well as on Centella asiatica (Apiaceae). The latter seems to be the most recent report of this fungus, dating from 2003 from Madagascar. There are no recent reports of the occurrence of C. tabacum other that its use in artificial inoculation experiments, as stressed by Damm et al. (2014), raising serious concerns on the conservation status of this species.

Colletotrichum tanaceti M. Barimani, S.J. Pethybridge, N. Vaghefi, F.S. Hay and P.W.J. Taylor, Plant Pathol. 62: 1248–1257 (2013)

Colletotrichum tanaceti is known to occur across the cultivation area of Tanacetum cinerariifolium (Asteraceae) in Australia (Barimani et al. 2013; Damm et al. 2014; Lelwala et al. 2019). The fungus appears to be host specific and may become of quarantine relevance.

Colletotrichum utrechtense Damm, Stud. Mycol. 79: 77 (2014)

Colletotrichum utrechtense is known from a single isolate, obtained from leaves of Trifolium pratense (Fabaceae) in the Netherlands in 2011 (Damm et al. 2014). Several other species of Colletotrichum are known from Trifolium and there are no other records of C. utrechtense, raising serious concerns about the conservation status of this taxon.

Colletotrichum vignae Damm, Stud. Mycol. 79: 78 (2014)

Colletotrichum vignae is known only from a single record obtained from cowpea (Vigna unguiculata, Fabaceae) in Nigeria prior to 1997 (Damm et al. 2014). The occurrence of several other species of Colletotrichum on Vigna and the absence of any other records of C. vignae, raise serious concerns about the conservation status of this fungal taxon, which may no longer exist in nature.

The dracaenophilum species complex

Together with the agaves, magnum and the orchidearum complexes, the dracaenophilum complex is one of the most recently described species complexes (Damm et al. 2019). The dracaenophilum species complex encompasses eight species distributed in the northern hemisphere (Asia, Europe and Mexico). Species belonging to this complex have been associated with nine plant species belonging to seven genera in monocots and eudicots. Due to the low number of representative isolates for each species, almost every lineage shows a certain level of specificity towards one genus, however more studies are needed to confirm the level of host preference (Fig. 9).

Fig. 9

Bayesian inference phylogenetic tree of the dracaenophilum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum cariniferi X.Y. Ma, K.D. Hyde and Jayawardena, MycoKeys 43: 23 (2018)

Colletotrichum cariniferi is known only from Dendrobium cariniferum (Orchidaceae), collected from stems in Thailand in 2013 (Ma et al. 2018). The pathological relevance and conservation status of this species remains to be analysed.

Colletotrichum coelogynes Damm, Stud. Mycol. 92: 1 (2019)

Colletotrichum coelogynes is known from a single isolate, obtained from Coelogyne sp. (Orchidaceae) leaves in Germany in 2010 (Damm et al. 2019). Another species, C. cymbidiicola, is also known from Coelogyne, raising concern on the conservation status of C. coelogynes.

Colletotrichum dracaenophilum D.F. Farr and M.E. Palm, Mycol. Res. 110: 1401 (2006)

Colletotrichum dracaenophilum is only known from Dracaena (D. sanderiana and D. braunii) in Brazil, Bulgaria, Egypt, China and Australia (Macedo and Barreto 2016; Morsy and Elshahawy 2016; Shivas et al. 2016; Damm et al. 2019) (Supplementary data 7). Other species of Colletotrichum are known from Dracaena, indicating that the conservation status of C. dracaenophilum should be under surveillance.

Colletotrichum excelsum-altitudinum G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 152 (2013)

Colletotrichum excelsum-altitudinum is only known from a single isolate collected from healthy Bletilla ochracea (Orchidaceae) leaves in China in 2006, along with several other species of Colletotrichum (Tao et al. 2013). Many species of Colletotrichum occur on this host and even more on orchids in general, most epiphytically, rendering the conservation status of Colletotrichum excelsum-altitudinum of great concern.

Colletotrichum parallelophorum X.Y. Ma, K.D. Hyde and Jayawardena, MycoKeys 43: 23 (2018)

This species is recorded only from an epiphytic fungus occurring on an unspecified species of Dendrobium (Orchidaceae) in Thailand in 2013 (Ma et al. 2018). There are no additional reports of this fungus and many other species of Colletotrichum occur on Dendrobium, raising serious concerns on the conservation status of C. parallelophorum.

Colletotrichum tongrenense S.X. Zhou, J.C. Kang and K.D. Hyde, MycoKeys 49: 1 (2009)

Colletotrichum tongrenense is known from a single isolate, obtained from symptomless leaves and stems of Nothapodytes pittosporoides (Icacinaceae) in China (Zhou et al. 2019). The ecological and conservation status of Colletotrichum tongrenense is unknown and of concern.

Colletotrichum tropicicola Phouliv., Noireung, L. Cai and K.D. Hyde, Cryptog. Mycol. 33: 353 (2012)

Colletotrichum tropicicola was designated based on two endophytic occurrences reported from Thailand in 2009 on leaves of Citrus maxima (Rutaceae) and Paphiopedilum bellatulum (Orchidaceae) (Noireung et al. 2012). Damm et al. (2019) identified isolates obtained from Citrus sp. in Mexico as belonging to Colletotrichum tropicicola, along with the Thai isolate from Citrus maxima, suggesting that the Paphiopedilum bellatulum isolate may lay in a separate, undescribed species. Colletotrichum tropicicola is still in a phase of delimitation, and consequently its ecological and conservation statuses need clarification.

Colletotrichum yunnanense Xiao Ying Liu and W.P. Wu, Mycotaxon 100: 139 (2007)

Colletotrichum yunnanense was described based on an isolate obtained from healthy leaves of an unspecified species of Buxus (Buxaceae) in China in 2004 (Liu et al. 2007; Weir et al. 2012), but no additional records have been reported ever since and reports of Colletotrichum from Buxus are seldom. The current conservation status of C. yunnanense is therefore of concern.

The gigasporum species complex

The gigasporum species complex (Fig. 10) was firstly described by Liu et al. (2014) encompassing six species. Colletotrichum gigasporum was identified and named based the formation of large (> 20 μm-long) conidia distinct from other currently known Colletotrichum species and confirmed by multi-locus phylogenetic analyses (ITS, act, tub2, chs-1 and gapdh). Recently three new members of this complex have been described: C. serranegrense, endophytic of Cattleya jongheana in Brazil (Silva et al. 2018), and C. jishouense and C. chiangraiense, endophytic species of Nothapodytes pittosporoides and Dendrobium sp. respectively in China (Ma et al. 2018; Zhou et al. 2019), although we exclude C. chiangraiense from the list of accepted species based on incongruence of the nucleotide sequence of the type strain (whereas the ITS sequence places this taxon in the boninense complex, the act and tub2 sequences place it in the gigasporum complex) as detailed in “Geographical distribution of Colletotrichum occurrences” section. Whereas C. serranegrense and C. jishouense have been described as members of the gigasporum species complex, C. chiangraiense has been described as a basal species of the boninense species complex, highlighting differences in the ITS clustering compared to the other genes. Further analyses will be needed to confirm the situation of C. chiangraiense. Species in the gigasporum complex have seldomly been reported (still C. gigasporum is the most common species), making this complex the less common of the genus.

Fig. 10

Bayesian inference phylogenetic tree of the gigasporum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act, tub2 and gs). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum arxii F. Liu, L. Cai, Crous and Damm, Persoonia 33: 87 (2014)

Colletotrichum arxii is known only from two isolates collected in Europe in the orchids Paphiopedilum sp. and Oncidium excavatum in 2010 and before 1956 respectively (Liu et al. 2014). There are multiple species of Colletotrichum inhabiting orchids, raising concern on the current conservation status of C. arxii.

Colletotrichum gigasporum E.F. Rakotoniriana and F. Munaut, Mycol. Prog. 12: 407 (2013)

Colletotrichum gigasporum occurs on several hosts, mostly in tropical regions across the globe (Rakotoniriana et al. 2013) (Supplementary data 8). Studies targeting the analysis of population frequency of Colletotrichum anthracnose pathogens on diverse hosts all coincide in revealing C. gigasporum as a secondary pathogen, including on Annona spp. in Brazil (Costa et al. 2019), coffee in Mexico (Cristóbal-Martínez et al. 2017) and in China (Cao et al. 2019a) and mango in China (Li et al. 2019b), prompting regular surveys to ascertain the conservation status of this species.

Colletotrichum jishouense SX. Zhou, JC. Kang and K.D. Hyde, MycoKeys 49: 1 (2019)

Colletotrichum jishouense has been recorded only from healthy roots of Nothapodytes pittosporoides (Icacinaceae), in China in 2016 (Zhou et al. 2019). Further research is needed to ascertain the host and geographic distribution of this taxon, as there is concern regarding its current conservation status.

Colletotrichum magnisporum F. Liu, L. Cai, Crous and Damm, Persoonia 33: 91 (2014)

Colletotrichum magnisporum is an enigmatic fungus, collected prior to 1984 from an unknown source (Liu et al. 2014). There are no additional records for this fungus, although metagenomics data suggest its occurrence in nature (Jayawardena et al. 2016a). Under these circumstances, the conservation status of C. magnisporum is of great concern and further surveys are needed to ascertain its occurrance on nature.

Colletotrichum pseudomajus F. Liu, L. Cai, Crous and Damm, Persoonia 33: 91 (2014)

Colletotrichum pseudomajus is known only from a single isolate, collected from Camellia sinensis (Theaceae) in China at an unknown date (prior to 1988) (Liu et al. 2014). The absence of any further records of this species and the occurrence of several species of Colletotrichum on Camellia spp. render the conservation status of C. pseudomajus of serious concern, with extinction from nature as a plausible scenario for this species.

Colletotrichum radicis F. Liu, L. Cai, Crous and Damm, Persoonia 33: 93 (2014)

There is a single isolate in the species Colletotrichum radicis, obtained from a root of an undetermined host in Costa Rica in 1993 (Liu et al. 2014). The scarcity of information on the ecological context of its isolation and the absence of any other records for this species hamper further surveys and strongly suggest that Colletotrichum radicis may be extinct from nature.

Colletotrichum serranegrense Meir. Silva & M.C.M. Kasuya, Phytotaxa 351: 163 (2018)

This species is known only from a single location, collected in Brazil in 2015 as a root endophyte of the endangered orchid Cattleya jongheana (Silva et al. 2018). Several other species of Colletotrichum have been obtained from Cattleya spp., rendering the conservation status of C. serranegrense of concern.

Colletotrichum vietnamense F. Liu, L. Cai, Crous and Damm, Persoonia 33: 93 (2014)

Colletotrichum vietnamense is known only from two isolates obtained from anthracnose symptoms on leaves of Coffea sp. (Rubiaceae) in Vietnam at an unknown date (Liu et al. 2014). The absence of any additional records of this taxon and the occurrence of several other species of Colletotrichum on Coffea raise serious concerns about the conservation status of C. vietnamense.

The gloeosporioides species complex

Like the acutatum complex, the gloeosporioides species complex was considered as one unique morphologically and phylogenetically diverse species. The name Colletotrichum gloeosporioides was firstly proposed in Penzig (1882), based on Vermicularia gloeosporioides, the type specimen of which was collected from Citrus in Italy. In the past century the term Colletotrichum gloeosporioides has undergone several usages and different taxonomists have kept agglomerating or dividing species under this name according with the evolution of the species concept. The revision performed by Weir et al. (2012) was a breakthrough in the taxonomy of this group and 22 species plus one subspecies were accepted as member of the gloeosporioides species complex. Nevertheless, the complex has undergone recurrent changes and several lineages have been merged and separated into novel species since then. One good example of the level of instability is provided by C. siamense. From 2009 to 2014, seven species with close phylogenetic affinities to C. siamense have been described and in some cases considered as species within C. siamense sensu lato (Liu et al. 2016c). Whereas some of these species (i.e. C. hymenocallidis and C. jasmini-sambac) were synonymised with C. siamense sensu stricto based on Weir et al. (2012), other authors resurrected those names describing C. siamense as a species complex. These changes have led to substantial disagreements regarding the taxonomy of this group. Finally, Liu et al. (2015a) used multiple approaches to demonstrate the lack of recognition of any independent evolutionary lineages within C. siamense sensu lato as distinct species, thus rejecting the null hypothesis. To date, 57 species have been described (Fig. 11) and despite significant developments, the taxonomy of this complex remains in a state of flux. Three major clades can be recognised in the complex (the theobromicola, kahawae and gloeosporioides clades), but phylogenetic distances between species vary strongly in each of these clades, mostly showing little geographical structure.

Fig. 11

Bayesian inference phylogenetic tree of the gloeosporioides species complex and closely related singleton species. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, act, tub2, cal, gs, sod2 and ApMat). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Members of the gloeosporioides species complex have been associated with 283 plant species belonging to 212 genera and the majority of those species (80.6%) belong to eudicots whereas only a smaller part belongs to monocots and gymnosperms (16.1% and 2.2% respectively). Members of the gloeosporioides species complex have also been reported as opportunistic pathogens of humans (Werbel et al. 2019).

Most of the species within the complex are polyphagous, but some show a strong specialisation towards one host. An example is provided by C. kahawae a highly aggressive and specialised pathogen of coffee, causing the devastating Coffee Berry Disease. This pathogen has the unique ability to infect green developing coffee berries and for its massive economic impact, it is ranked as a quarantine pathogen and even as a biological weapon (Australia Group 2014; Batista et al. 2017).

The gloeosporioides complex is the most common and polyphagous species complex of the genus.

Colletotrichum aenigma B. Weir and P.R. Johnst., Stud. Mycol. 73: 135 (2012)

Colletotrichum aenigma was described based only on two isolates (Weir et al. 2012), but was subsequently recognised as inhabiting multiple hosts in diverse locations, namely: Actinidia arguta (Actinidaceae) in China (Wang et al. 2019a); Aquilaria sinensis (Thymelaeaceae) in China (Liu et al. 2021a); Camellia japonica, C. oleifera, C. sasanqua and C. sinensis (Theaceae) in China (Wang et al. 2016, 2020a; Chen et al. 2019a; Yang et al. 2019a); Capsicum sp. (Solanaceae) in China (Diao et al. 2017); Citrus sinensis (Rutaceae) in Italy (Schena et al. 2014); Cyclocarya paliurus (Juglandaceae) in China (Zheng et al. 2021b); Fragaria × ananassa (Rosaceae) in China (Han et al. 2016; Chen et al. 2020); Hylocereus undatus (Cactaceae) in Thailand (Meetum et al. 2015); Juglans regia (Juglandaceae) in China (Wang et al. 2021e); Malus domestica (Rosaceae) in China (Zhang et al. 2021b); Olea europaea (Oleaceae) in Italy (Schena et al. 2014); Persea americana (Lauraceae) in Israel (Weir et al. 2012; Sharma et al. 2017); Populus sp. (as Colletotrichum populi) in China (Li et al. 2012); Pyrus bretschneideri (Rosaceae) in China (Fu et al. 2019), P. communis in Italy (Mosca et al. 2014; Schena et al. 2014) and P. pyrifolia in China and Japan (Weir et al. 2012; Fu et al. 2019); Sedum kamtschaticum (Crassulaceae) in Korea (Choi et al. 2017); Vitis vinifera (Vitaceae) in China (Yan et al. 2015) and Korea (Kim et al. 2021). Colletotrichum aenigma thus seems to be a fungus in expansion, hosted by numerous agricultural crop plants (Supplementary data 9, panel A).

Colletotrichum aeschynomenes B. Weir and P.R. Johnst., Stud. Mycol. 73: 135 (2012)

Besides being a pathogen of the weed Aeschynomene indica (Fabaceae) in the USA (Weir et al. 2012), Colletotrichum aeschynomenes was recently reported in Brazil as causing anthracnose in cacao (Theobroma cacao; Malvaceae) (Nascimento et al. 2019a) and in Myrciaria dubia (Myrtaceae) (Matos et al. 2020) and as an endophyte on Vellozia gigantea (Velloziaceae) (Ferreira et al. 2017), as well as from Thailand on Manihot esculenta (Euphorbiaceae) with unconfirmed pathogenicity (Sangpueak et al. 2018).

Colletotrichum alatae B. Weir and P.R. Johnst., Stud. Mycol. 73: 135 (2012)

Colletotrichum alatae is recorded only from water yam (Dioscorea alata, Dioscoreaceae) from America, Africa and Asia (Weir et al. 2012; Lin et al. 2018b). It is a common and host-specific fungus.

Colletotrichum alienum B. Weir and P.R. Johnst., Stud. Mycol. 73: 139 (2012)

Colletotrichum alienum is recorded as a pathogen from multiple dicotyledonous hosts in Oceania, Asia, Africa and Europe (Supplementary data 9, panel B), namely on: Aquilaria sinensis in China (Thymelaeaceae; Liu et al. 2020a); Camellia sinensis in China (Theaceae; Liu et al. 2015a); Diospyros kaki in New Zealand (Ebenaceae; Weir et al. 2012); Fragaria × ananassa in Australia (Rosaceae; Shivas et al. 2016); Grevillea sp. in Australia (Proteaceae; Liu et al. 2013a); Leucadendron sp. in Portugal and South Africa (Proteaceae; Liu et al. 2013a); Malus domestica in New Zealand (Rosaceae; Weir et al. 2012); Mangifera indica in China (Anacardiaceae; Ahmad et al. 2021); Nerium oleander in Australia (Apocynaceae; Schena et al. 2014); Persea americana in Australia, New Zealand and Israel (Lauraceae; Weir et al. 2012; Sharma et al. 2017); Protea cynaroides in Portugal and South Africa (Proteaceae; Liu et al. 2013a); Serruria sp. in South Africa (Proteaceae; Liu et al. 2013a). Additionally, it was recently recorded in Mexico as a pathogen in mango (Mangifera indica; Tovar-Pedraza et al. 2020) and in Uruguay associated to olive anthracnose (Moreira et al. 2021), suggesting its spread to America.

Colletotrichum aotearoa B. Weir and P.R. Johnst., Stud. Mycol. 73: 139 (2012)

This species is reported from numerous native angiosperms and gymnosperms from Australia and New Zealand (Supplementary data 9, panel C) either as pathogen or as endophyte (Weir et al. 2012; Liu et al. 2013a; Shivas et al. 2016), including: the Araliaceae Meryta sinclairii; the Berberidaceae Berberis glaucocarpa; the Lamiaceae Vitex lucens; the Loganiaceae Geniostoma rupestre var. ligustrifolium; the Meliaceae Dysoxylum spectabile; the Monimiaceae Hedycarya angustifolia; the Myrtaceae Syzygium smithii (as Acmena smithii) and Kunzea ericoides; the Oleaceae Ligustrum lucidum; the Podocarpaceae Dacrycarpus dacrydioides, Podocarpus totara and Prumnopitys ferruginea; the Proteaceae Banksia marginata and Knightia sp.; the Rubiaceae Coprosma sp.; the Violaceae Melicytus ramiflorus. It was also found on banana in India and classified as “slightly pathogenic” (Sharma et al. 2015). The presence of C. aotearoa on Boehmeria in China needs to be confirmed (Weir et al. 2012).

Colletotrichum arecicola X.R. Cao, H.Y. Che and D.Q. Luo, Plant Dis. 104: 1369 (2020)

Colletotrichum arecicola was recently described as a leaf pathogen of Areca catechu in China (Cao et al. 2020). Whereas there were no previous occurrences of Colletotrichum reported from Areca hosts, that study detected several species of Colletotrichum occurring on Areca catechu, suggesting that further surveys are necessary to ascertain the pathological relevance, geographic distribution and conservation status of C. arecicola.

Colletotrichum artocarpicola Bhunjun, Jayawardena, Jeewon and K.D. Hyde, Phytotaxa 418: 273 (2019)

Colletotrichum artocarpicola was collected as a saprobe from a dead root of jackfruit (Artocarpus heterophyllus, Moraceae) in Thailand in 2018 (Bhunjun et al. 2019). The pathological and conservation status of thus fungus remains to be investigated. The host plant is a widely cultivated tropical fruit tree.

Colletotrichum asianum Prihastuti, L. Cai and K.D. Hyde, Fungal Divers. 39: 96 (2009)

Colletotrichum asianum is isolated recurrently and with high frequency as a pathogen of mango (Mangifera indica) from different parts of the world (Supplementary data 9, panel D), typically along with C. siamense and several other species (Li et al. 2019a,b; Tovar-Pedraza et al. 2020; Benatar et al. 2021). It was also recently reported from avocado (Persea americana) in Indonesia (Zhafarina et al. 2021).

Colletotrichum australianum W. Wang, D. D. De Silva, and P. W. J. Taylor, J. Fungi 7:47 (2021)

The species Colletotrichum australianum was recently described to accomodate fungi found in association with citrus anthracnose in Australia, namely on Citrus reticulata and C. sinensis (Wang et al. 2021c). The species also encompasses a fungus previously identified as Colletotrichum queenslandicum, isolated from chilli (Capsicum annuum). The pathological relevance and host range of C. australianum remains to be established, but this fungus may become of quarantine relevance.

Colletotrichum camelliae Massee, Bull. Misc. Inf., Kew: 91 (1899)

Colletotrichum camelliae is known only from Camellia spp. (Wang et al. 2016, 2020a; Lu et al. 2018; Win et al. 2018; He et al. 2019). Besides one isolate collected in the USA in 1982 (Liu et al. 2015a), the pathogen seems to be more frequent in Asia (Supplementary data 9, panel E).

Colletotrichum changpingense G. Zhang, Jayawardena and K.D. Hyde, Mycosphere 7: 1155 (2016)

There are two records for Colletotrichum changpingense, obtained from diseased strawberry (Fragaria × ananassa) rhizomes in China in 2011 and 2012 (Jayawardena et al. 2016b). There are multiple Colletotrichum species associated with strawberry plants and the pathological relevance and the ecological status of C. changpingense require clarification.

Colletotrichum chiangmaiense N.I. de Silva, Lumyong & K.D. Hyde, Mycosphere 12(1): 192 (2021)

Colletotrichum chiangmaiense is known from a single isolate collected as an endophyte in leaves of Magnolia garrettii (Magnoliaceae) in 2017 in Thailand (De Silva et al. 2021a, b). There are no further records of this fungus and other species of Colletotrichum are known from other Magnolia spp., rendering the conservation status of this taxon of concern.

Colletotrichum chrysophilum W.A.S. Vieira, W.G. Lima, M.P.S. Câmara and V.P. Doyle, Mycologia 109: 912 (2017)

The taxon Colletotrichum chrysophilum was recently described based on fungi causing anthracnose on banana plants (Musa acuminata) in Brazil, but also containing fungi previously assigned to C. ignotum E.I. Rojas, S.A. Rehner and Samuels, which includes endophytes of Theobroma cacao (Malvaceae), Genipa americana (Rubiaceae), Tetragastris panamensis (Burseraceae) and Terpsichore taxifolia (Polypodiaceae) from Panama and Puerto Rico (Vieira et al. 2017). The fungus was also found in Brazil as a causal agent both of cashew (Anacardium spp.) anthracnose (Veloso et al. 2018) and of cassava (Manihot esculenta) anthracnose (Machado et al. 2021a), and was also associated to banana and avocado anthracnose in Mexico (Fuentes-Aragón et al. 2020, 2021). The importance of this taxon as an avocado, banana, cassava or cashew pathogen requires further investigation. Being currently restricted to the American continent, it may become a quarantine pathogen for these crops in other continents.

Colletotrichum cigarro (B.S. Weir and P.R. Johnston) A. Cabral and P. Talhinhas, Plants 9: 502 (2020)

Colletotrichum cigarro, recently named by raising C. kahawae ssp. cigarro to the species rank (Cabral et al. 2020), is known from numerous hosts and regions, including the Proteaceae Banksia sp. and Dryandra sp. in Portugal (Madeira) and Spain (Weir et al. 2012; Liu et al. 2013a), Leucospermum sp. in the USA (Hawai) (Weir et al. 2012) and Toronia toru in New Zealand (Weir et al. 2012), the Rosaceae Dryas octopetala in Switzerland (Weir et al. 2012), apple (Malus domestica) in Belgium and the USA (Grammen et al. 2019; McCulloch et al. 2020) and Rubus glaucus in Colombia (Afanador-Kafuri et al. 2014), the Myrtaceae Eucalyptus grandis in South Africa (Mangwende et al. 2020) and Kunzea ericoides in New Zealand (Weir et al. 2012), as well as on Areca catechu (Arecaceae) in China (Zhang et al. 2020d), Citrus reticulata (Rutaceae) in Italy (Perrone et al. 2016), Eruca vesicaria (as E. sativa, Brassicaceae) in Italy (Garibaldi et al. 2016a), Hypericum perforatum (Hypericaceae) in Germany (Weir et al. 2012), Liquidambar styraciflua (Altingiaceae) in Italy (Garibaldi et al. 2016b; Guarnaccia et al. 2021), mango (Mangifera indica, Anacardiaceae) in Colombia and Italy (Ismail et al. 2015; Pardo-De La Hoz et al. 2016), Miconia sp. (Melastomataceae) in Brazil (Weir et al. 2012), Morus alba (Moraceae) in China (Xue et al. 2019), olive (Olea europaea, Oleaceae) in Australia and Italy (Weir et al. 2012; Schena et al. 2014), avocado (Persea americana, Lauraceae) in Korea and New Zealand (Weir et al. 2012; Kwon et al. 2020), tree tomato (Solanum betaceum, Solanaceae) in Colombia (Rojas et al. 2018) and Vaccinium macrocarpum (Ericaceae) in the USA (Weir et al. 2012). Colletotrichum cigarro is thus a common fungus worldwide (Supplementary data 9, panel F).

Colletotrichum clidemiae B.S. Weir and P.R. Johnst., Stud. Mycol. 73: 148 (2012)

Colletotrichum clidemiae is known from the USA and Panama on Clidemia hirta (Melastomataceae), and from the USA on Vitis sp. and Quercus sp. (Weir et al. 2012). No additional isolates have been reported since the taxon was described, indicating that the conservation status of C. clidemiae requires clarification.

Colletotrichum cobbittiense S. Luo, G. Dong and P. Wong, Persoonia 40: 240 (2018)

Colletotrichum cobbittiense includes a single isolate collected from leaf lesions of Cordyline stricta × C. australis (Asparagaceae) in Australia in 2016 (Crous et al. 2018c). There are several species of Colletotrichum occurring on Cordyline, rendering the pathological status of C. cobbittiense uncertain and its conservation status of concern.

Colletotrichum conoides Y.Z. Diao, C. Zhang, L. Cai and X.L. Liu, Persoonia 38: 27 (2017)

The species Colletotrichum conoides was designated based on an isolate collected from Capsicum annuum var. conoides fruits in China in 2010 (Diao et al. 2017). The fungus was subsequently found associated with anthracnose symptoms on Pyrus pyrifolia in China in 2015 (Fu et al. 2019). Both hosts harbour numerous species of Colletotrichum, rendering the pathological status of C. conoides uncertain and its conservation status of concern.

Colletotrichum cordylinicola Phoulivong, L. Cai and K. D. Hyde, Mycotaxon 114: 251 (2011)

Colletotrichum cordylinicola is known from Cordyline spp. (Asparagaceae) in the USA (Sharma et al. 2014) and Thailand, from Eugenia sp. (Myrtaceae) in Laos and from Areca catechu (Arecaceae) in China (Cao et al. 2020). Additional species of Colletotrichum are reported from these hosts, rendering the pathological status of C. cordylinicola uncertain and its conservation status of concern.

Colletotrichum cycadis Andjic, Maxwell & Smith, Persoonia 45:251-409 (2020)

The species Colletotrichum cycadis was described based on fungi isolated from leaf spots on Cycas revoluta (Cycadaceae) plants originary from China (Crous et al. 2020). Records of Colletotrichum spp. on Cycas are seldom, but given the ornamental importance of these plants, the pathological relevance of this fungus needs to be studied.

Colletotrichum dracaenigenum Chaiwan & K.D. Hyde, Phytotaxa 491:143-157 (2021)

Colletotrichum dracaenigenum was described based on a single isolate obtained in 2017 in Thailand on dead leaves of Dracaena fragrans (Asparagaceae) and assumed as a saprobe (Chaiwan et al. 2021). Given that there are several species of Colletotrichum on Dracaena spp., the conservation status of C. dracaenigenum is uncertain and of concern.

Colletotrichum endophyticum Manamgoda, Udayanga, L. Cai and K.D. Hyde, Fungal Divers. 61: 110 (2013)

Colletotrichum endophyticum was reported as an endophyte collected in Thailand in 2010 on Pennisetum purpureum (Poaceae) and on an unknown wild fruit (Manamgoda et al. 2013), and subsequently found as an endophyte on Capsicum annuum fruits in Thailand and in China (Diao et al. 2017; De Silva et al. 2019). Nevertheless, C. endophyticum was found as an anthracnose pathogen associated to Camellia sinensis leaves (Wang et al. 2016), to coffee (Coffea arabica and C. robusta) leaves and fruits (Cao et al. 2019a) and to mango leaves and fruits (Li et al. 2019b) in China. Colletotrichum endophyticum could be emerging in Southeast Asia and may be of pathological concern to the host crops (tea, coffee and mango) in which it was shown to be pathogenic. However, any of these three crops harbour a vast array of Colletotrichum species, suggesting attentive surveys for the presence and spread of C. endophyticum.

Colletotrichum fructicola Prihastuti, L. Cai and K.D. Hyde, Fungal Divers. 39: 96 (2009)

Colletotrichum fructicola is a cosmopolitan fungus, found in all continents and in a wide range of host plants (Supplementary data 9, panel G), but mostly occurring in tropical and sub-tropical regions. Colletotrichum fructicola typically occurs along other Colletotrichum species associated to anthracnose symptoms, often being a less frequent and/or less virulent population. However, several reports consistently place C. fructicola as the most frequently isolated fungus associated with apple bitter rot in South America (Alaniz et al. 2019; Moreira et al. 2019a; Velho et al. 2019), in contrast with C. fioriniae as the main causal agent of this disease in North America and Europe. Other reports where C. fructicola was recorded as the main anthracnose pathogen are on Annona spp. in Brazil (Costa et al. 2019) and on Pyrus spp. (Fu et al. 2019), strawberry (Jayawardena et al. 2016b), tea plant (Camellia sinensis; Wang et al. 2016) and tea-oil tree (Camellia oleifera; Wang et al. 2020a) in China.

Colletotrichum fructivorum V.P. Doyle, P.V. Oudem. and S.A. Rehner, PLoS ONE 7: e51392 (2012)

Colletotrichum fructivorum includes isolates obtained in the USA from fruits of cultivated Vaccinium macrocarpon and wild V. oxycoccos (Ericaceae) and stems of Rhexia virginica (Melastomataceae) in 2009–2010 (Doyle et al. 2013) (Supplementary data 9, panel H). However, no further occurrences of C. fructivorum have been reported ever since, raising concern on its conservation status.

Colletotrichum gloeosporioides (Penz.) Penz. and Sacc., Atti Inst. Veneto Sci. Lett., ed Arti, Sér. 6 (2): 670 (1884)

For over 100 years the limits of the taxon Colletotrichum gloeosporioides have changed several times. Following Cannon et al. (2008) and Weir et al. (2012), modern C. gloeosporioides, or C. gloeosporioides sensu stricto, was defined based on fungi occurring on Citrus spp., as well as on hosts such as Ficus, Mangifera, Pueraria and Vitis, suggesting that this taxon was not of cosmopolitan distribution (Phoulivong et al. 2010). However, in the last decade, C. gloeosporioides sensu stricto was recorded in a vast number of hosts and locations in addition to those hosts: okra (Abelmoschus esculentus, Malvaceae) in China (Shi et al. 2019); Acca sellowiana (Myrtaceae) in Brazil (Fantinel et al. 2017); Acer coriaceifolium (Sapindaceae) in China (Zhu et al. 2020); Actinidia spp. (Actinidiaceae) in China (Deng et al. 2017; Li et al. 2017a); Akebia trifoliata (Lardizabalaceae) in China (Pan et al. 2021); Annona spp. (Annonaceae) in Brazil (Costa et al. 2019), Colombia (Álvarez et al. 2014) and Italy (Schena et al. 2014); Anoectochilus roxburghii (Orchidaceae) in China (Chen et al. 2016b); Areca catechu (Arecaceae) in China (Cao et al. 2020); Atalantia citroides (Rutaceae) in Spain (Guarnaccia et al. 2017); Barringtonia edulis (Lecythidaceae) in Papua New Guinea (Buyoyu et al. 2017); Bauhinia blakeana (Fabaceae) in China (Li et al. 2016a); Camellia oleifera and C. sinensis (Theaceae) in China (Guo et al. 2014a; Wang et al. 2020a); chilli (Capsicum spp., Solanaceae) in China (Diao et al. 2017; Li et al. 2021); Catalpa fargesii f. duciouxii (Bignoniaceae) in China (Fu et al. 2013); Chaenomeles sinensis (Rosaceae) in China (Ni et al. 2021); Choerospondias axillaris (Anacardiaceae) in China (Li et al. 2017b); Arabica coffee (Coffea arabica, Rubiaceae) in Mexico (Cristóbal-Martínez et al. 2017); Crataegus gracilior (Rosaceae) in Mexico (Nieto-López et al. 2018); Cunninghamia lanceolata (Cupressaceae) in China (Huang et al. 2019); Cyclocarya paliurus (Juglandaceae) in China (Zheng et al. 2021b); Dendrobium officinale (Orchidaceae) in China (Lan et al. 2016); Elaeocarpus sylvestris (Elaeocarpaceae) in China (Li et al. 2016b); Elettaria cardamomum (Zingiberaceae) in India (Chethana et al. 2016); loquat (Eriobotrya japonica, Rosaceae) in Pakistan (Naz et al. 2017); Euonymus japonicus (Celastraceae) in China (Huang et al. 2016); Falcataria moluccana (as Albizia falcataria, Fabaceae) in China (Chen et al. 2019b); Hymenocallis littoralis (Amaryllidaceae) in China (Zhao et al. 2019); walnut (Juglans regia, Juglandaceae) in China (Wang et al. 2020b; Yang et al. 2021); Ligustrum japonicum (Oleaceae) in China (Shen et al. 2017); Liriodendron chinense × tulipifera (Magnoliaceae) in China (Zhu et al. 2019a); Liriope cymbidiomorpha (Asparagaceae) in China (Yang et al. 2020); Magnolia candolli (Magnoliaceae) in China (De Silva et al. 2021a, b); Malus pumila (Rosaceae) in Korea (Cheon et al. 2016); Mikania micrantha (Asteraceae) in China (Zhu et al. 2019b); banana (Musa acuminata, Musaceae) in Ecuador, Malaysia and Pakistan (Intan Sakinah et al. 2013; Riera et al. 2019; Alam et al. 2021); olive (Olea europaea, Oleaceae) in Italy, Portugal and Tunisia (Mosca et al. 2014; Chattaoui et al. 2016; Talhinhas et al. 2018); Osmanthus fragrans (Oleaceae) in China (Tang et al. 2018); Oxalis corniculata (Oxalidaceae) in Brazil (Bellé et al. 2019); Paeonia lactiflora (Paeoniaceae) in China (Zhang and Dai 2017); avocado (Persea americana, Lauraceae) in Israel and Turkey (Akgül et al. 2016; Sharma et al. 2017); Pouteria caimito (Sapotaceae) in China (Duan et al. 2018b); Pteridium aquilinum (Dennstaedtiaceae) in China (Tan et al. 2017); pomegranate (Punica granatum, Lythraceae) in the USA (Xavier et al. 2019); Pyrus spp. (Rosaceae) in China (Fu et al. 2019); Quercus glauca (Fagaceae) in China (Liu et al. 2021c); Robinia pseudoacacia (Fabaceae) in China (Xue et al. 2018a); rose (Rosa sp., Rosaceae) in South Korea (Hassan et al. 2019b); Rubia cordifolia (Rubiaceae) in China (Tang and Tan 2020); Sedum kamtschaticum (Crassulaceae) in South Korea (Jeon and Kwak 2016); Smilax sieboldii (Smilacaceae) in China (Zhang et al. 2017); Sorbaria sorbifolia (Rosaceae) in China (Li et al. 2019c; Wang et al. 2021a); Syzygium samarangense (Myrtaceae) in Malaysia (Al-Obaidi et al. 2017); Viburnum odoratissimum (Adoxaceae) in China (Yang et al. 2015). Colletotrichum gloeosporioides sensu stricto is thus a cosmopolitan fungus (Supplementary data 9, panel I), inhabiting a wide range of host plants.

Colletotrichum grevilleae F. Liu, Damm, L. Cai and Crous, Fungal Divers. 61: 98 (2013)

Colletotrichum grevilleae is known only from a single isolate collected from root and collar rot of Grevillea sp. (Proteaceae) in Italy in 2000 (Liu et al. 2013a). No further occurrences of C. grevilleae have been reported ever since and several other species of Colletotrichum occur on Grevillea, raising great concern on its conservation status.

Colletotrichum grossum Y.Z. Diao, C. Zhang, L. Cai and X.L. Liu, Persoonia 38: 29 (2017)

The species Colletotrichum grossum was recently defined based on one isolate collected from Capsicum annuum var. grossum in China in 2011 (Diao et al. 2017). The fungus was recently identified on chilli in Italy (Guarnaccia et al. 2021). The scarcity of reports of C. grossum and the occurrence of several other species of Colletotrichum on chilli raise concern on the conservation status of this species.

Colletotrichum hebeiense X.H. Li, Y. Wang, K.D. Hyde, M.M.R.S. Jayawardena and J.Y. Yan, Fungal Divers. 71: 241 (2015)

Colletotrichum hebeiense is defined based on two isolates obtained from grapes (Vitis vinifera) in two locations in China in 2009 (Yan et al. 2015). No additional occurrences of C. hebeiense have been recorded ever since. Considering that a vast list of species of Colletotrichum is known from Vitis spp., the conservation status of C. hebeiense is of serious concern.

Colletotrichum hederiicola Jayaward., Camporesi and K.D. Hyde, Fungal Divers. 100: 5 (2020)

The species Colletotrichum hederiicola was recently coined to accommodate a fungus isolated as a saprobe from a dead branch of ivy (Hedera helix, Araliaceae) in Italy in 2014 (Hyde et al. 2020a). No further records of C. hederiicola are known. Colletotrichum trichellum, also reported from Hedera spp., is also seldom. The conservation status of C. hederiicola is therefore of great concern.

Colletotrichum helleniense Guarnaccia and Crous, Persoonia 39: 32 (2017)

Colletotrichum helleniense is a taxon containing isolates associated with citrus anthracnose, namely from wither-tip twigs of Citrus reticulata and C. trifoliata (as Poncirus trifoliata, Rutaceae) from the same location in Greece in 2015 (Guarnaccia et al. 2017). No additional occurrences of C. helleniense have been recorded ever since and numerous species of Colletotrichum occur on citrus, rendering the conservation status of C. helleniense of concern.

Colletotrichum henanense F. Liu and L. Cai, Persoonia 35: 80 (2015)

Colletotrichum henanense was described based on two isolates obtained in China from tea (Camellia sinensis, Theaceae) in 2012 and from Cirsium japonicum (Asteraceae) in 2010 (Liu et al. 2015a). Subsequently the fungus was detected also in China, causing anthracnose on Camellia oleifera in 2016 (Li et al. 2018c). This is the single report of Colletotrichum on Cirsium, suggesting that this is not a common host of Colletotrichum spp. On the other hand, there are many species of Colletotrichum reported on Camellia spp., raising concerns on the conservation status of Colletotrichum henanense.

Colletotrichum horii B. Weir and P.R. Johnst., Mycotaxon 111: 211 (2010)

Colletotrichum horii is defined based on fungal pathogens of persimmon (Diospyros kaki, Ebenaceae) from China, Korea, Japan and New Zealand (Weir and Johnston 2010). The fungus has subsequently been reported from Brazil associated to twig blight and defoliation (Mio et al. 2015), with further reports from Korea showing severe infections (Kwon et al. 2013; Jeon et al. 2017; An et al. 2018). Colletotrichum horii is apparently specific to persimmon, occurring commonly in Asia (Supplementary data 9, panel J) and may be considered a quarantine pathogen elsewhere.

Colletotrichum hystricis Guarnaccia and Crous, Persoonia 39: 32 (2017)

The species Colletotrichum hystricis includes a single isolate obtained from a leaf lesion of Citrus hystrix (Rutaceae) in Italy in 2016 (Guarnaccia et al. 2017). The occurrence of multiple species of Colletotrichum on citrus renders the conservation status of C. hystricis of serious concern.

Colletotrichum jiangxiense F. Liu and L. Cai, Persoonia 35: 82 (2015)

The species Colletotrichum jiangxiense was designated based on two isolates collected from tea plant (Camellia sinensis, Theaceae) in China in 2013 (Liu et al. 2015a). The species was subsequently identified as an endophyte on Dendrobium sp. (Orchidaceae) in Thailand (Ma et al. 2018) and associated to avocado (Persea americana, Lauraceae) anthracnose in Mexico (Ayvar-Serna et al. 2021). The uncertainty about its pathological status and the occurrence of vast numbers of species of Colletotrichum on its hosts raise concern about the conservation status of C. jiangxiense.

Colletotrichum kahawae J.M Waller and Bridge, Mycol. Res. 97(8): 993 (1993)

Colletotrichum kahawae is found in Africa in Coffea spp. (Rubiaceae), causing the Coffee Berry Disease (Waller et al. 1993; Cabral et al. 2020). This fungus has undergone a host-jump speciation process (Silva et al. 2012a) accompanied by a genome size expansion (Pires et al. 2016), becoming biologically and phylogenetically isolated from the closely related Colletotrichum cigarro (Cabral et al. 2020). Although common in Africa (Supplementary data 9, panel K), this pathogen is of quarantine concern in coffee growing regions in Asia and America (Batista et al. 2017).

Colletotrichum makassarense D.D. De Silva, P.W. Crous and P.W.J. Taylor, IMA Fungus 10: 8 (2019)

The taxon Colletotrichum makassarense was designated to accommodate a single isolate obtained from chilli (Capsicum annuum, Solanaceae) in Indonesia (De Silva et al. 2019). No further isolates of Colletotrichum makassarense have been reported and many other species of Colletotrichum are known from chilli, raising high concern about the conservation status of this species.

Colletotrichum musae (Berk. and M. A. Curtis) Arx and Verh. K. ned. Akad. Wet., tweede sect. 51(3): 107 (1957)

Colletotrichum musae is the causal agent of banana (Musa sp., Musaceae) anthracnose, occurring worldwide (Supplementary data 9, panel L) as a common post-harvest disease (Weir et al. 2012).

Colletotrichum nupharicola D.A. Johnson, Carris and J.D. Rogers, Mycol. Res. 101: 647 (1997)

The species Colletotrichum nupharicola was described based on isolates collected from the water lilies Nuphar lutea and Nymphaea odorata (Nymphaeaceae) in the USA in the 1990s (Weir et al. 2012). No further occurrences of C. nupharicola have been recorded thereafter, but this taxon has been reported recently from avocado (Persea americana, Lauraceae) in Israel (Sharma et al. 2017). The geographic distribution, pathological relevance and conservation status of C. nupharicola are thus unknown and require further investigation.

Colletotrichum pandanicola Tibpromma and K.D. Hyde, MycoKeys 33: 25 (2018)

This species is recorded only from an epiphytic fungus occurring on leaves on an unspecified species of Pandanus (Pandanaceae) in Thailand in 2016 (Tibpromma et al. 2018). There are no additional reports of this fungus and other species of Colletotrichum occur on Pandanus, raising serious concerns on the conservation status of C. pandanicola.

Colletotrichum perseae G. Sharma and S. Freeman, Sci. Rep. 17: 15839 (2017)

Colletotrichum perseae was reported from several locations in Israel in 2014, among several other species of Colletotrichum, as the prevailing pathogen associated to leaf spots and fruit rot of avocado (Persea americana, Lauraceae) (Sharma et al. 2017). The fungus was recently detected in New Zealand, also associated to mango anthracnose (Hofer et al. 2021). The pathological relevance of C. perseae to avocado cultivation remains to be analysed, suggesting that it may be considered a quarantine pathogen.

Colletotrichum proteae F. Liu, Damm, L. Cai and Crous, Fungal Divers. 61: 100 (2013)

Colletotrichum proteae is known from a single isolate, collected from an unspecified species of Protea (Proteaceae) in South Africa in 2008 (Liu et al. 2013a). Its pathological condition is not known and there are several other species of Colletotrichum occurring on Protea and on Proteaceae, which raises severe concerns about the conservation status of C. proteae.

Colletotrichum pseudotheobromicola Chethana, Yan, Li and K.D. Hyde, Mycosphere 10: 518 (2019)

Colletotrichum pseudotheobromicola has been recently named to accommodate a fungus associated to leaf spots of Prunus avium (Rosaceae) in China (Chethana et al. 2019). This is the single report of this species and there are numerous species of Colletotrichum occurring on Prunus (and even specifically on P. avium), suggesting that the pathological relevance and the conservation status of C. pseudotheobromicola require further investigation.

Colletotrichum psidii Curzi, Atti Ist. bot. R. Univ. Pavia, 3 Sér. 3: 207 (1927)

Colletotrichum psidii is known from a single occurrence, collected from guava (Psidium sp., Myrtaceae) in Italy, prior to 1927 (Weir et al. 2012). The only available culture in collection is reported as sterile (Weir et al. 2012). The absence of any further records of this species, along with the occurrence of several other species of Colletotrichum on guava, suggests that Colletotrichum psidii may be extinct.

Colletotrichum queenslandicum B. Weir and P.R. Johnst., Stud. Mycol. 73: 164 (2012)

Colletotrichum queenslandicum was originally described from papaya (Carica papaya, Caricaceae) and avocado (Persea americana, Lauraceae) in Australia and from cashew (Anacardium occidentale, Anacardiaceae) in Brazil (Veloso et al. 2018) and coffee (Coffea sp., Rubiaceae) in Fiji (Weir et al. 2012). It was subsequently reported from persian lime (Citrus × latifolia, Rutaceae) in the USA (Kunta et al. 2018), from Licania tomentosa (Chrysobalanaceae) in Brazil (Lisboa et al. 2018), from lychee (Litchi chinensis, Sapindaceae) in Australia (Anderson et al. 2013; Shivas et al. 2016), from mango (Mangifera indica, Anacardiaceae) in Australia (Shivas et al. 2016), from Nephelium lappaceum (Sapindaceae) in Puerto Rico (Serrato-Diaz et al. 2017), from olive (Olea europaea, Oleaceae) in Montenegro (Schena et al. 2014) and from passionfruit (Passiflora edulis, Passifloraceae) in Australia (Shivas et al. 2016). Such recent reports of C. queenslandicum, besides confirming this as a common fungus in Australia, revealed its presence in America and Europe (Supplementary data 9, panel M), associated to woody agricultural crops. The pathological relevance and the host range of C. queenslandicum should be analysed, namely in a quarantine perspective.

Colletotrichum rhexiae Ellis and Everh., Proc. Acad. nat. Sci. Philad. 46: 372 (1894)

Colletotrichum rhexiae is known from Rhexia virginica (Melastomataceae) leaf and stem lesions and from Vaccinium macrocarpon (Ericaceae) fruit lesions in the USA (Doyle et al. 2013). No additional reports of this species have occurred, suggesting that it is geographically confined and that it may not occur on major agricultural crops. Further surveys would improve current knowledge on the conservation status of C. rhexiae.

Colletotrichum salsolae B. Weir and P.R. Johnst., Stud. Mycol. 73: 164 (2012)

Colletotrichum salsolae is known from Salsola kali subsp. tragus (Amaranthaceae), occurring throughout the geographic range of the host (Weir et al. 2012). Recently, the fungus was reported as a causal agent of anthracnose on papaya (Carica papaya, Caricaceae) fruits in India, along with Colletotrichum gloeosporioides (Saini et al. 2017a).

Colletotrichum siamense Phoulivong, L. Cai and K.D. Hyde, Fungal Divers. 39: 98 (2009)

Liu et al. (2016c) synonymised several species (namely Colletotrichum communis, C. dianesei, C. endomangiferae, C. hymenocallidis, C. jasmini-sambac and C. murrayae) to C. siamense, thus recognising its occurrence on multiple hosts, to which add additional recent reports. Colletotrichum siamense is thus known from Alocasia macrorrhizos (Araceae), Alpinia purpurata (Zingiberaceae), Amorphophallus paeoniifolius (Araceae), Anacardium occidentale, A. humile and A. othonianum (Anacardiaceae), Annona muricata (Annonaceae), Areca catechu (Arecaceae), Artocarpus heterophyllus and A. sericicarpus (Moraceae), Azadirachta indica (Meliaceae), Bauhinia forficata and B. variegata (Fabaceae), Camellia chrysantha, C. oleifera and C. sinensis (Theaceae), Capsicum annuum, C. chinensis and C. frutescens (Solanaceae), Carica papaya (Caricaceae), Carya illinoiensis (Juglandaceae), Cassia fistula (Fabaceae), Cercis chinensis (Fabaceae), Cinnamomum kotoense (Lauraceae), Citrus limon, C. pennivesiculata, C. reticulata and C. sinensis (Rutaceae), Cocos nucifera (Arececeae), Coffea arabica and C. canephora (Rubiaceae), Commelina sp. (Commelinaceae), Corchorus capsularis (Malvaceae), Cornus hongkongensis (Cornaceae), Cycas debaoensis (Cycadaceae), Cymbopogon citratus (Poaceae), Datura metel (Solanaceae), Dieffenbachia sp. (Araceae), Dionaea muscipula (Droseraceae), Dioscorea cayennensis ssp. rotundata (Dioscoreaceae), Diospyros kaki (Ebenaceae), Dypsis lutescens (as Chrysalidocarpus lutescens, Arececeae), Elettaria cardamomum (Zingiberaceae), Ensete superbum (Musaceae), Eriobotrya japonica (Rosaceae), Euonymus japonicus (Celastraceae), Ficus carica and F. elastica (Moraceae), Fragaria × ananassa (Rosaceae), Hevea brasiliensis (Euphorbiaceae), Hibiscus sp. (Malvaceae), Hylocereus lemairei (as Hylocereus polyrhizus) and H. undulatus (Cactaceae), Hymenocallis littoralis (as Hymenocallis americana, Amaryllidaceae), Iris tectorum (Iridaceae), Jasminum mesnyi and J. sambac (Oleaceae), Juglans regia (Juglandaceae), Licania tomentosa (Chrysobalanaceae), Liriodendron chinense × tulipifera (Magnoliaceae), Litchi chinensis (Sapindaceae), Macadamia integrifolia (Proteaceae), Machilus ichangensis (Lauraceae), Malus domestica (Rosaceae), Mandevilla sp. (Apocynaceae), Mangifera indica (Anacardiaceae), Manihot esculenta (Euphorbiaceae), Mentha sp. (Lamiaceae), Michelia alba (Magnoliaceae), Musa acuminata (Musaceae), Nelumbo nucifera (Nelumbonaceae), Nopalea cochenillifera (Cactaceae), Ocimum basilicum (Lamiaceae), Olea europaea (Oleaceae), Parthenocissus tricuspidata (Vitaceae), Pennisetum purpureum (Poaceae), Persea americana (Lauraceae), Piper nigrum (Piperaceae), Pistachia vera (Anacardiaceae), Plukenetia volubilis (Euphorbiaceae), Plumeria alba (Apocynaceae), Pongamia pinnata (Fabaceae), Protea cynaroides (Proteaceae), Prunus persica (Rosaceae), Psidium guajava (Myrtaceae), Punica granatum (Lythraceae), Pyrus communis and P. pyrifolia (Rosaceae), Rosa chinensis (Rosaceae), Rosmarinus officinalis (Lamiaceae), Salix matsudana (Salicaceae), Saraca indica (Fabaceae), Sarcandra glabra (Chloranthaceae), Sophora tonkinensis (Fabaceae), Sterculia nobilis and S. lanceolata (Malvaceae), Theobroma cacao (Malvaceae), Uraria picta (Fabaceae), Vaccinium macrocarpon (Ericaceae), Viola odorata (Violaceae) and Vitis vinifera (Vitaceae) (Weir et al. 2012; Cheng et al. 2013, 2019; Doyle et al. 2013; Liu et al. 2013a, 2017a; Manamgoda et al. 2013; Udayanga et al. 2013; Álvarez et al. 2014; Schena et al. 2014; Larran et al. 2015; Meetum et al. 2015; Sharma et al. 2015; Dwarka et al. 2016; Niu et al. 2016a; Shivas et al. 2016; Watanabe et al. 2016; Ye et al. 2016; Zhou et al. 2016; Conforto et al. 2017; Douanla-Meli and Unger 2017; Katoch et al. 2017; Kumar et al. 2017; Ni et al. 2017; Prasad et al. 2017; Vieira et al. 2017; Wang et al. 2017, 2020c, 2021c, 2021d; Chang et al. 2018b; Naik et al. 2018; Oliveira et al. 2018; Veloso et al. 2018; Xavier et al. 2018, 2019; Zhao et al. 2018, 2020, 2021a; Abirami et al. 2019; Cao et al. 2019b; Chaves et al. 2019; Chou et al. 2019; Feng et al. 2019; Fu et al. 2019; Ji et al. 2019; Zhang 2019b, 2020a, 2020b, 2021a, 2021d; Zhu et al. 2019a; Chen et al. 2020; Prasannath et al. 2020; Wu 2020; Borges et al. 2021; Carbone et al. 2021; Eaton et al. 2021; Han et al. 2021; Hofer et al. 2021; Huang et al. 2021a,b; Ismail et al. 2021a,b; Oh et al. 2021; Oo et al. 2021; Qin et al. 2021; Rodríguez-Palafox et al. 2021; Song et al. 2021; Zhafarina et al. 2021). Colletotrichum siamense is a fungus with a very broad host range and found throughout the world (Supplementary data 9, panel N), although prevailing in Australasia and tropical America, whereas it seems to be quite rare in Europe.

Colletotrichum syzygiicola Udayanga, Manamgoda and K.D. Hyde, Fungal Divers. 61: 173 (2013)

Colletotrichum syzygiicola was first described from anthracnose symptoms on Citrus aurantifolia (Rutaceae) and Syzygium samarangense (Myrtaceae) fruits collected in Thailand in 2010 (Udayanga et al. 2013). The fungus was subsequently associated to anthracnose of Elettaria cardamomum (Zingiberaceae) in India (Chethana et al. 2016). Records of Colletotrichum syzygiicola are still seldom and each of the hosts is known to harbour other species of Colletotrichum, raising concern on the actual occurrence of this fungus in nature.

Colletotrichum tainanense D.D. De Silva, P.W. Crous and P.W.J. Taylor, IMA Fungus 10: 8 (2019)

Colletotrichum tainanense is known from a single report obtained from fruits of Capsicum annuum (Solanaceae) in China in 2014 (De Silva et al. 2019). There are no additional reports for this taxon and multiple species of Colletotrichum occur on this host, raising severe concerns about the conservation status of C. tainanense.

Colletotrichum temperatum V. Doyle, P.V. Oudem. and S.A. Rehner, PLoS One 7: e51392 (2012)

Colletotrichum temperatum is known from two isolates collected from fruit rot and asymptomatic stems of Vaccinium macrocarpon (Ericaceae) in the USA in 2009 (Doyle et al. 2013). There are no further reports of this species and there are numerous other species of Colletotrichum recorded on Vaccinium, raising serious concerns about the conservation status of C. temperatum.

Colletotrichum theobromicola Delacr., Bull. Soc. Mycol. Fr. 21: 191 (1905)

Colletotrichum theobromicola, as defined by Weir et al. (2012) following Rojas et al. (2010) description, is a fungus with a broad host range, upon the placement of C. fragariae and Colletotrichum gloeosporioides f. stylosanthis in synonymy to it. Thereafter, the fungus has been found on other hosts, being currently known from: Acca sellowiana (Myrtaceae) (Weir et al. 2012); Aeschynomene falcata (Fabaceae) (Shivas et al. 2016); Allium cepa and A. fistulosum (Amaryllidaceae) (Matos et al. 2017; Lopes et al. 2021); Anacardium occidentale (Anacardiaceae) (Veloso et al. 2018); Annona macroprophyllata (as A. diversifolia), A. muricata and A. squamosa (Annonaceae) (Weir et al. 2012; Álvarez et al. 2014; Costa et al. 2019); Buxus microphylla var. japonica (Buxaceae) (Singh et al. 2015); Campomanesia phaea (Myrtaceae) (Santos et al. 2017); Carapichea ipecacuanha (Rubiaceae) (Ferreira et al. 2020); Coffea arabica (Rubiaceae) (Shivas et al. 2016; Cristóbal-Martínez et al. 2017); Copernicia prunifera (Arececeae) (Araújo et al. 2018); Cyclamen persicum (Primulaceae) (Sharma et al. 2016); Fragaria × ananassa (Rosaceae) (Weir et al. 2012); Limonium sp. (Plumbaginaceae) (Weir et al. 2012); Malpighia emarginata (Malpighiaceae) (Bragança et al. 2014); Malus domestica (Rosaceae) (Alaniz et al. 2015; Munir et al. 2016); Mangifera indica (Anacardiaceae) (Sharma et al. 2013; Pardo-De la Hoz et al. 2016); Manihot esculenta (Euphorbiaceae) (Oliveira et al. 2018); Manilkara zapota (Sapotaceae) (Martins et al. 2018); Musa sp. (Musaceae) (Vieira et al. 2017); Olea europaea (Oleaceae) (Weir et al. 2012; Lima et al. 2020; Moreira et al. 2021); Persea americana (Lauraceae) (Sharma et al. 2017); Punica granatum (Lythraceae) (Shivas et al. 2016; Xavier et al. 2019); Quercus sp. (Fagaceae) (Weir et al. 2012); Stylosanthes guianensis and S. viscosa (Fabaceae) (Weir et al. 2012); Theobroma cacao (Malvaceae) (Rojas et al. 2010). Colletotrichum theobromicola is thus a predominantly tropical and sub-tropical fungus (Supplementary data 9, panel O), with a growing host range, and of pathological relevance.

Colletotrichum ti B. Weir and P.R. Johnst., Stud. Mycol. 73: 171 (2012)

Colletotrichum ti is a fungus exhibiting pathogenic host specificity to Cordyline australis (Asparagaceae) and found only in New Zealand (Weir et al. 2012). There are other species of Colletotrichum known from Cordyline (although not from New Zealand) which, along with the absence of recent reports of C. ti, raise concern about the conservation status of this species.

Colletotrichum tropicale E.I. Rojas, S.A. Rehner and Samuels, Mycologia 102(6): 1331 (2010)

Originally described as a fungus occurring as a leaf endophyte of several host species in tropical forests of Panama (Rojas et al. 2010), Colletotrichum tropicale has been identified from numerous hosts in many parts of the world (Supplementary data 9, panel P): Anacardium occidentale (Anacardiaceae) in Brazil (Veloso et al. 2018); Annona cherimola and A. muricata (Annonaceae) in Brazil, Colombia, Cuba and Panama (Rojas et al. 2010; Álvarez et al. 2014; García and Manzano 2017; Costa et al. 2019); Areca catechu (Arecaceae) in China (Cao et al. 2020); Capsicum annuum and C. frutescens (Solanaceae) in Indonesia and Brazil respectively (De Silva et al. 2017a, 2019); Cattleya spp. (Orchidaceae) in Brazil (Silva-Cabral et al. 2019); Coffea sp. (Rubiaceae) in China (Cao et al. 2019a); Copernicia prunifera (Arecaceae) in Brazil (Araújo et al. 2018); Cordia alliodora (Boraginaceae) in Panama (Rojas et al. 2010); Ficus binnendijkii (Moraceae) in China (Kong et al. 2020); Licania tomentosa (Chrysobalanaceae) in Brazil (Lisboa et al. 2018); Litchi chinensis (Sapindaceae) in Japan (Weir et al. 2012); Mangifera indica (Anacardiaceae) in Brazil, China and Mexico (Lima et al. 2013; Li et al. 2019b; Tovar-Pedraza et al. 2020); Manihot dichotoma and M. epruinosa (Euphorbiaceae) in Brazil (Oliveira et al. 2016); Musa sp. (Musaceae) in Brazil (Vieira et al. 2017); Myrciaria dubia (Myrtaceae) in Brazil (Matos et al. 2020); Passiflora edulis in Brazil (Silva et al. 2021a, b); Persea americana (Lauraceae) in Mexico (Fuentes‐Aragón et al. 2020); Plinia cauliflora (as Myrciaria cauliflora, Myrtaceae) in Japan (Taba et al. 2020); Nelumbo nucifera (Nelumbonaceae) in China (Xavier et al. 2018); Origanum vulgare (Lamiaceae) in Mexico (Ayvar-Serna et al. 2020); Pennisetum purpureum (Poaceae) in Thailand (Manamgoda et al. 2013); Punica granatum (Lythraceae) in Brazil (Silva-Cabral et al. 2019); Sauropus androgynus (Phyllanthaceae) in China (Liu et al. 2018); Theobroma cacao (Malvaceae) in Panama (Rojas et al. 2010); Trichilia tuberculata (Meliaceae) in Panama (Rojas et al. 2010); Viola surinamensis (Violaceae) in Panama (Rojas et al. 2010); human eye (Hung et al. 2020). Colletotrichum tropicale is thus a cosmopolitan and polyphagous species, of contemporary widespread occurrence.

Colletotrichum viniferum L.J. Peng, L. Cai, K.D. Hyde and Z-Y. Ying, Mycoscience 54: 36 (2013)

Colletotrichum viniferum was described as a pathogen of grapes (Vitis vinifera) in China (Peng et al. 2013), where it is the most prevalent and virulent causal agent of grape anthracnose (Yan et al. 2015). The fungus was subsequently recorded from grapevine in Korea (Oo and Oh 2017a), from Hopea odorata (Dipterocarpaceae) in Bangladesh (Rashid et al. 2020) and from chilli (Capsicum sp.; Diao et al. 2017), strawberry (Fragaria × ananassa; He et al. 2019) and walnut (Juglans regia; He et al. 2019) in China. Considering the geographical distribution currently known for this fungus (Supplementary data 9, panel Q), along with the high virulence to grapevines and the expanding host range, Colletotrichum viniferum should be regarded with concern regarding its pathological relevance and potential quarantine status.

Colletotrichum wuxiense Y.C. Wang, X.C. Wang and Y.J. Yang, Sci. Rep. 6: 35287 (2016)

Colletotrichum wuxiense was described based on an isolate obtained from diseased leaves of Camellia sinensis (Theaceae) in China in 2014 (Wang et al. 2016) and subsequently identified associated to anthracnose symptoms on Pyrus pyrifolia (Rosaceae) also in China, in 2016 (Fu et al. 2019). Considering the large number of species of Colletotrichum known from both hosts, further surveys are important to reveal the pathological and ecological relevance of C. wuxiense, as well as its conservation status.

Colletotrichum xanthorrhoeae R.G. Shivas, Bathgate and Podger, Mycol. Res. 102: 280 (1998)

Colletotrichum xanthorrhoeae was described based on isolates obtained from Xanthorrhoea spp. (Xanthorrhoeaceae) in Australia in the 1990s (Shivas et al. 1998; Weir et al. 2012), but no additional records have been reported ever since. The current conservation status of C. xanthorrhoeae is therefore of concern.

Colletotrichum xishuangbannaense N.I. de Silva, Lumyong & K.D. Hyde, Mycosphere 12(1):195 (2021)

Colletotrichum xishuangbannaense is known from a single isolate collected as an endophyte in leaves of Magnolia candolli (Magnoliaceae) in 2017 in China (De Silva et al. 2021a, b). There are no further records of this fungus and other species of Colletotrichum are known from this and other Magnolia spp., rendering the conservation status of this taxon of concern.

Colletotrichum yulongense C.L. Hou and X.T. Liu, Phytotaxa 394: 285 (2019)

Colletotrichum yulongense is known only from a single occurrence, as an endophyte on leaves of Vaccinium dunalianum var. urophyllum in China in 2013 (Wang et al. 2019b). There are other species of Colletotrichum occurring on Vaccinium, suggesting that the ecological and conservation status of C. yulongense must be clarified.

The graminicola species complex

Firstly described by Cannon et al. (2012) and in agreement with studies published by Crouch et al. (2009a, b), the graminicola complex is a well-defined monophyletic clade encompassing Colletotrichum species mainly associated with grasses and with characteristic widely falcate conidia.

MLST approaches initially revealed two major subclades within the graminicola clade (Crouch et al. 2009a, b). The first one is represented only by Colletotrichum cereale, a species associated with C3 grasses as either pathogens or endophytes (Crouch et al. 2009b). The second subclade encompasses apparently host-specific species associated with C4 grasses. More recently a third clade has been recognised and described as the caudatum species complex (see the section above). Currently the graminicola complex encompasses 16 species (Fig. 12) pathogenic to different lineages of Poaceae but also endophytes of Poaceae and Orchidaceae (both monocot plants). Several of the species included in the graminicola clade are of major importance, including C. falcatum on sugarcane, C. graminicola on maize and C. sublineola on Sorghum species. Colletotrichum cereale and C. eremochloae are pathogens of cultivated turfgrasses (Crouch and Beirn 2009). Beside the economic impact, the maize pathogen C. graminicola is an important model system (O’Connell et al. 2012).

Fig. 12

Bayesian inference phylogenetic tree of the graminicola species complex and closely related singleton species. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, chs-1, act, tub2, sod2 and apn2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum axonopodi J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 727 (2009)

There are four records for this species, collected in the first half of the twentieth century in the USA and Honduras and in 1983 in Australia, on Axonopodus spp. (Poaceae) (Crouch et al. 2009a). Although anthracnose of Axonopus was associated to C. axonopodi (Crouch and Beirn 2009), more recently C. hainanense was described as an additional causal agent of this disease (Zhang et al. 2020c). The current conservation status of C. axonopodi is therefore uncertain and of concern.

Colletotrichum cereale Manns, Proc. Indiana Acad. Sci.: 111 (1908)

Besides being a pathogen of grasses (Poaceae) throughout the world (Crouch et al. 2009a) (Supplementary data 10, panel A) (inspite of scarce records; Zhao et al. 2021b), C. cereale was also reported as an endophyte from Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013).

Colletotrichum echinochloae Moriwaki and Tsukib., Mycoscience 50: 275 (2009)

Colletotrichum echinochloae is only known from Echinochloa utilis (Poaceae) in Japan, collected over the years (Moriwaki and Tsukiboshi 2009). This fungus seems to be host-specific and geographically-confined, suggesting its ecological status to be under survey.

Colletotrichum eleusines Pavgi and U.P. Singh, Mycopath. Mycol. Appl. 27: 85 (1965)

Colletotrichum eleusines is known from few and ancient (1936 and 1977) records, collected from Eleusine indica (Poaceae) in the USA and Japan (Crouch et al. 2009a). No other species of Colletotrichum have been recorded from this host, but the lack of recent reports of C. eleusines raises serious concern on its conservation status.

Colletotrichum endophytum G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 152 (2013)

Colletotrichum endophytum is known only from two isolates collected from healthy leaves of Bletilla ochracea (Orchidaceae) in two locations in China in 2006 (Tao et al. 2013). No additional occurrences of C. endophytum were recorded thereafter, and several species of Colletotrichum occur on Bletilla (and even more so on orchids), rendering the conservation status of C. endophytum of great concern.

Colletotrichum eremochloae J.A. Crouch and Tomaso-Pet., Mycologia 104: 1092 (2012)

Colletotrichum eremochloae has been recorded in the USA (including on a shipment from China in 1923) in different moments during the twentieth century and more recently in 2007 associated to anthracnose symptoms on Eremochloa ophiuroides (Poaceae) (Crouch and Tomaso-Peterson 2012). Although the fungus seems to be host specific, its seldom occurrence raises concern on its conservation status.

Colletotrichum falcatum Went, Archiv, voor de Java Suekerrind. 1: 265 (1893)

Colletotrichum falcatum is the causal agent of red rot of sugarcane, found in all continents were the host plant (Saccharum officinarum) is cultivated (Crouch et al. 2009a) (Supplementary data 10, panel B).

Colletotrichum graminicola (Ces.) G.W. Wilson, Phytopathology 4: 110 (1914)

Colletotrichum graminicola is considered a pathogen of maize (Zea mays, Poaceae), reported from different parts of the world (Crouch et al. 2009a) (Supplementary data 10, panel C). Recent reports are mostly from Europe, including Bosnia and Herzegovina, Portugal and Switzerland (Sukno et al. 2014; Sanz-Martín et al. 2016; Cuevas-Fernández et al. 2019), but also from China (Duan et al. 2019). The fungus is also reported as a human opportunistic pathogen (Valenzuela‐Lopez et al. 2018).

Colletotrichum hanaui J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 728 (2009)

The species Colletotrichum hanaui was defined to accommodate fungi isolated from Digitaria ciliaris and D. sanguinalis (Poaceae) in the USA and Japan in the 1940s and in 1975, respectively (Crouch et al. 2009a). Although there are no other species of Colletotrichum recorded on Digitaria spp., the lack of contemporary records of C. hanaui raises serious concerns on the conservation status of this taxon.

Colletotrichum hainanense W. Zhang and X. L. Niu, Plant Dis. 104:1744 (2020)

Colletotrichum hainanense was recently named to accommodate fungi causing anthracnose of Axonopus compressus (Poaceae) in China in 2015 (Zhang et al. 2020c). Colletotrichum axonopodi is also associated to anthracnose in this host, rendering the conservation status of C. hainanense of concern.

Colletotrichum jacksonii J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 729 (2009)

Colletotrichum jacksonii is known from Echinochloa esculenta (Poaceae) in Japan and E. crus-galli in the USA, recorded respectively in the 1977–1985 and in the 1912–1943 periods (Crouch et al. 2009a). The lack of recent records, along with the identification of a different species (C. echinochloae) more recently in Japan, raises serious concerns on the conservation status of C. jacksonii.

Colletotrichum miscanthi J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 729 (2009)

Originally defined based on an isolate obtained from Miscanthus sinensis (Poaceae) in Japan in 1972 (Crouch et al. 2009a), the fungus was detected thereafter only once, as an endophyte on Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). Colletotrichum miscanthi is thus a species of elusive pathological relevance and with its conservation status of high concern.

Colletotrichum navitas J.A. Crouch, Mycol. Res. 113: 1417 (2009)

Crouch et al. (2009b) designated the species Colletotrichum navitas based on numerous isolates collected from the USA on Panicum virgatum (Poaceae) throughout the twentieth century, as well as on P. crus-galli, P. curtisii and P. hemitomon. There are no records of the fungus outside of the USA, suggesting further surveys to ascertain the geographical distribution and current conservation status of C. navitas.

Colletotrichum nicholsonii J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 730 (2009)

Colletotrichum nicholsonii is known from Paspalum dilatatum (Poaceae) from Japan, New Zealand and the USA, with isolates collected between 1965 and 1975 (Crouch et al. 2009a). Although Paspalum dilatatum is a cosmopolitan plant, no additional occurrences of C. nicholsonii have been recorded since 1975, indicating that the current existence of this species in nature must be scrutinised.

Colletotrichum paspali J.A. Crouch, B.B. Clarke, J.F. White and B.I. Hillman, Mycologia 101: 730 (2009)

Colletotrichum paspali is known only from two records, collected in the 1970s, on Paspalum notatum (Poaceae) in Japan (Crouch et al. 2009a). There are no other species of Colletotrichum recorded from Paspalum notatum, but C. nicholsonii has also been recorded from Paspalum dilatatum in Japan. Considering the absence of recent reports of C. paspali, its conservation status is of serious concern.

Colletotrichum sublineola Henn. ex Sacc. and Trotter, Syll. Fung. (Abellini) 22: 1206 (1913)

Colletotrichum sublineola is the sorghum (Sorghum spp.) anthracnose pathogen (Crouch and Tomaso-Peterson 2012). Effective records are known from Africa, America and Korea (Supplementary data 10, panel D), but the disease is known from virtually the entire sorghum cultivation area (Crouch and Tomaso-Peterson 2012; Tsedaley et al. 2016; Xavier et al. 2018; Bunker et al. 2019; Choi et al. 2021). The fungus appears to be common, but a recent review on sorghum anthracnose is lacking.

The magnum species complex

The magnum complex is one of the most recently described species complexes (Damm et al. 2019). Sister clade of the orchidearum complex, the magnum species complex encompasses eight accepted species (Fig. 13). Whereas almost all of them have been reported only once or in one host in one country, Colletotrichum brevisporum seems to be a quite common species as it has been associated with at least 20 plant species belonging to 18 genera (both monocots and eudicots) in Asia, Oceania and South America. Like for other uncommon or rare species, not much is available about the host spectrum, the specificity or the lifestyle of the other members of the complex.

Fig. 13

Bayesian inference phylogenetic tree of the magnum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum brevisporum Noireung, Phouliv., L. Cai and K.D. Hyde, Cryptog. Mycol. 33: 350 (2012)

Colletotrichum brevisporum is recorded from several hosts in tropical and sub-tropical regions throughout the world (Damm et al. 2019) (Supplementary data 11), including: Annona sp. (Annonaceae) in Brazil (Costa et al. 2019); Anthurium sp. (Araceae) in Thailand (Damm et al. 2019); Capsicum annuum (Solanaceae) in China and Trinidad and Tobago (Liu et al. 2016c; Damm et al. 2019; Villafana et al. 2019) and C. chinense and C. frutescens in Brazil (Almeida et al. 2017; Oliveira et al. 2017; Silva et al. 2017b; Damm et al. 2019); Carapichea ipecacuanha (Rubiaceae) in Brazil (Ferreira et al. 2020); Carica papaya (Caricaceae) in Australia, Brazil and China (Vieira et al. 2013; Shivas et al. 2016; Duan et al. 2018a; Damm et al. 2019; Liu et al. 2019c); Citrus medica (Rutaceae) in China (Guarnaccia et al. 2017); Coffea sp. (Rubiaceae) in China (Cao et al. 2019a); Colocasia esculenta (Araceae) in Mexico (Vásquez-López et al. 2019); Glycine max (Fabaceae) in China (Shi et al. 2021); Lycium chinense (Solanaceae) in Korea (Damm et al. 2019); Momordica cochinchinensis (Cucurbitaceae) in Thailand (Chai et al. 2018); Neoregelia sp. (Bromeliaceae) in Thailand (Damm et al. 2019); Pandanus pygmaeus (Pandanaceae) in Thailand (Damm et al. 2019); Passiflora edulis (Passifloraceae) in Australia and China (Shivas et al. 2016; Du et al. 2017; Qiu et al. 2021); Sechium edule (Cucurbitaceae) in Brazil (Bezerra et al. 2016).

Colletotrichum cacao Damm, in Stud. Mycol. 92: 1 (2019)

Colletotrichum cacao is known from a single isolate collected as an endophyte from Theobroma cacao in Costa Rica at an unknown date (Damm et al. 2019). Several other species of Colletotrichum are recorded on this host, raising great concern on the current ecological status of C. cacao.

Colletotrichum liaoningense Y.Z. Diao, C. Zhang, L. Cai and X.L. Liu, Persoonia 38: 34 (2017)

Colletotrichum liaoningense occurs on chilli (Capsicum sp., Solanaceae) in China (Diao et al. 2017; Damm et al. 2019), but it was recently identified in China associated to anthracnose on mango (Mangifera indica, Anacardiaceae) (Li et al. 2019b) and on Solanum pseudocapsicum (Solanaceae; Liu et al. 2021a). Both chilli and mango harbour many species of Colletotrichum, rendering the conservation status of C. liaoningense of concern.

Colletotrichum lobatum Damm, Stud. Mycol. 92: 1 (2019)

Colletotrichum lobatum is known from a single isolate obtained from Piper marginatum f. catalpifolium (as Piper catalpifolium, Piperaceae) in Trinidad and Tobago in an unknown date (Damm et al. 2019). There are no further occurrences of C. lobatum recorded and several other species of Colletotrichum are known from Piper spp., raising serious concern on the conservation status of this species.

Colletotrichum magnum (S.F. Jenkins and Winstead) Rossman and W.C. Allen, IMA Fungus 7:1 (2016)

Originally defined as a pathogen of watermelon (Citrullus lanatus, Cucurbitaceae) (Rossman et al. 2016), Colletotrichum magnum is seldom reported: it was identified causing anthracnose on papaya (Carica papaya, Caricaceae) in Mexico in 2014 (Tapia-Tussell et al. 2016) and on Lobelia chinensis (Campanulaceae) in China in 2014 (Li et al. 2013). Further surveys will convey additional information about the pathological relevance and conservation status of Colletotrichum magnum.

Colletotrichum merremiae Damm, Stud. Mycol. 92: 1 (2019)

The species Colletotrichum merremiae was described based on an isolate occurring as a leaf endophyte of Merremia umbellata (Convolvulaceae) in Panama in 2004 (Damm et al. 2019). There are no additional records for this fungus, indicating that the conservation status of C. merremiae is of serious concern.

Colletotrichum okinawense Damm and Toy. Sato, Stud. Mycol. 92: 1 (2019)

Colletotrichum okinawense was described based on two isolates collected from papaya (Carica papaya) stems/petioles in Brazil and in Japan in 1892 and 2007 respectively (Damm et al. 2019). However, the fungus was subsequently re-identified in Brazil in 2018 associated to papaya fruit anthracnose (Dias et al. 2020). The scarcity of reports of Colletotrichum okinawense along with the large number of other species of Colletotrichum occurring on papaya renders the pathological relevance of this species uncertain and raises concern about its conservation status.

Colletotrichum panamense Damm, Stud. Mycol. 92: 1 (2019)

Colletotrichum panamense is known from a single isolate, occurring as an epiphyte on Merremia umbellata (Convolvulaceae) in Panama in 2004 (Damm et al. 2019). There are no further records for this taxon and other species of Colletotrichum are known from this host, casting great concern on the conservation status of C. panamense.

The orbiculare species complex

Introduced by Cannon et al. (2012) as a small aggregate of only two species, the orbiculare species complex has been widely described by Damm et al. (2013) based on MLST and morphological characters. Analysis performed by the authors resulted in nine clades that confirmed four species previously known, Colletotrichum lindemuthianum, C. malvarum, C. orbiculare and C. trifolii, and recognised four new species from weeds, namely C. bidentis, C. sidae, C. spinosum and C. tebeestii. Most of them are known for their hemibiotrophic infection strategy and as destructive pathogens either of field crops or weeds (Fig. 14). While initially the species included in the orbiculare complex were considered host specific, new reports suggest that most of them are rather specialised, but not exclusive, to a group of hosts. Overall members of this complex have been associated with 19 host species belonging to 16 genera, with a vast majority of eudicot hosts and only one report on Asparagus racemosus (Asparagaceae, monocot). Colletotrichum lindemuthianum is a well-known bean pathogen and the most common species of the complex, followed by C. orbiculare, causal agent of anthracnose of Cucurbitaceae, and C. trifolii, a species pathogenic of alfalfa, red clover and mallow.

Fig. 14

Bayesian inference phylogenetic tree of the orbiculare species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act, tub2 and gs). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum bidentis Damm, Guatimosim and Vieira, Fungal Divers. 61: 34 (2013)

There is a single record for Colletotrichum bidentis, isolated from Bidens subalternans (Asteraceae) in Brazil in 2010 (Damm et al. 2013). Bidens spp. are recorded from all over the world, often as invasive weeds, but the conservation status of C. bidentis is of concern.

Colletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cavara, Funghi Parass. Piante Colt. od Utili, Fasc. 2: no. 50 (1889)

The common bean (Phaseolus vulgaris and. P. coccineus, Fabaceae) anthracnose pathogen, Colletotrichum lindemuthianum, is found all over the world (Supplementary data 12, panel A), and it develops a singular race-dependent interaction with the host (Liu et al. 2013b; Padder et al. 2017).

Colletotrichum malvarum (A. Braun and Casp.) SouthW., J. Mycol. 6: 116 (1891)

Only two strains were considered as belonging to Colletotrichum malvarum by Damm et al. (2013), obtained from Malva sp. and Lavatera trimestris (Malvaceae) in Germany and UK respectively, with several other reports of anthracnose pathogens on Malvaceae either assigned to different species or requiring further investigation. No reports of C. malvarum have arose ever since, laying high concern over the conservation status of this species.

Colletotrichum orbiculare Damm, P.F. Cannon and Crous, Fungal Divers. 61: 39 (2013)

Colletotrichum orbiculare was newly described by Damm et al. (2013) encompassing fungi occurring on (and as important pathogens of) the Cucurbitaceae Cucumis melo, Cucurbita pepo and Lagenaria spp. Recently the species was also recorded from other Cucurbitaceae such as Benincasa hispida in Australia (Shivas et al. 2016) and watermelon (Citrullus lanatus) in the USA (Rennberger et al. 2018) (Supplementary data 12, panel B).

Colletotrichum sidae Damm and P.F. Cannon, Fungal Divers. 61: 44 (2013)

Colletotrichum sidae is known only from Sida spinosa (Malvaceae) in the USA only (Damm et al. 2013). The scarcity of recent reports of Colletotrichum sidae raises concerns on its conservation status.

Colletotrichum spinosum Damm and P.F. Cannon, Fungal Divers. 61: 46 (2013)

Damm et al. (2013) revised literature on the occurrence of Colletotrichum spinosum, revealing this fungus to be common in Australia and to occur also in Argentina on Xanthium spinosum (Asteraceae). However, there are no recent records of this fungus, while other species of Colletotrichum are reported from the host, suggesting further surveys to ascertain the conservation status of C. spinosum.

Colletotrichum tebeestii Damm and P.F. Cannon, Fungal Divers. 61: 48 (2013)

Colletotrichum tebeestii was described based on a fungus isolated from Malva pusilla (Malvaceae) in Canada (Damm et al. 2013). Fungi from this species were developed as mycoherbicides, but there is a lack of current reports of this fungus, raising concern about the current conservation status of this species.

Colletotrichum trifolii Bain, J. Mycol. 12: 193 (1906)

Colletotrichum trifolii is known from Fabaceae (Medicago sativa and Trifolium pratense) in the USA (Damm et al. 2013; Samac et al. 2014), but also from Malva crispa and M. sylvestris (Malvaceae) in China (Zhou et al. 2014; Liu et al. 2017c) and, as an endophyte, from Viola odorata (Violaceae) in India (Katoch et al. 2017). Future surveys may improve the knowledge on the host range and geographic distribution of C. trifolii.

The orchidearum species complex

The orchidearum complex is the last of the four most recently described species complexes (Damm et al. 2019; Bhunjun et al. 2021). Sister clade of the magnum complex, the orchidearum species complex encompasses eight accepted species (Fig. 15). Unlike the other two closely related aggregates, most of the species encompassing this complex are quite common and polyphagous. Overall members of this complex have been associated with 35 plant species belonging to 31 genera (almost the same proportion between eudicots and monocots). Interestingly several species belonging to this clade (Colletotrichum sojae, C. plurivorum and C. musicola) have been reported to be serious problems of an important crop such as soybean (Rogério et al. 2020).

Fig. 15

Bayesian inference phylogenetic tree of the orchidearum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum cattleyicola Damm and Toy. Sato, Stud. Mycol. 92: 1 (2019)

Colletotrichum cattleyicola is known from unspecified species of Cattleya (Orchidaceae; root and stem), collected in Belgium prior to 1949 and in Japan around 2000 (Damm et al. 2019). The pathological status of Colletotrichum cattleyicola is unknown and its conservation status is of concern, as several other species of Colletotrichum are recorded on orchids.

Colletotrichum cliviicola Damm and Crous, Stud. Mycol. 92: 1 (2019)

Colletotrichum cliviicola, recently described in replacement of C. cliviae Yan L. Yang et al., includes isolates obtained from Clivia spp. (Amaryllidaceae) in China in 2008 and in South Africa in 2012 (Damm et al. 2019), along with isolates obtained in China from Pennisetum americanum × P. purpureum (Poaceae) (Han et al. 2019) and Mangifera indica (Li et al. 2019b) (Supplementary data 13, panel A).

Colletotrichum musicola Damm, Stud. Mycol. 92: 1 (2019)

The species Colletotrichum musicola was defined based on an isolate collected from Musa sp. (Musaceae) in Mexico in 2008 (Damm et al. 2019). Subsequently the fungus was identified associated to leaf anthracnose of taro (Colocasia esculenta, Araceae) in 2017, also in Mexico (Vásquez-López et al. 2019). So far restricted to Mexico, the host range of Colletotrichum musicola remains to be elucidated, along with its pathological relevance and conservation status.

Colletotrichum orchidearum Allesch., Rabenh. Krypt.-Fl., Edn 2 (Leipzig) 1: 563 (1903)

Damm et al. (2019) provide a description of Colletotrichum orchidearum and placed C. hymenocallidicola and C. aracearum as its synonyms. As such, C. orchidearum is known from Dendrobium nobile and Eria javanica (Orchidaceae) in the Netherlands and Germany respectively, Epipremnum aureum, Monstera deliciosa and Philodendron bipinnatifidum (as P. selloum) (Araceae) in Iran and China respectively and Hymenocallis sp. (Amaryllidaceae) in Thailand (Ariyawansa et al. 2015; Hou et al. 2016; Damm et al. 2019). Thus, the geographic distribution (Supplementary data 13, panel B) and host range of C. orchidearum requires further investigation in order to clarify its conservation status.

Colletotrichum piperis Petch, Ann. R. bot. Gdns Peradeniya 6: 239 (1917)

Damm et al. (2019) listed four isolates under Colletotrichum piperis, collected from Piper betle, P. nigrum and P. umbellatum (Piperaceae) in China, Malaysia, Sri Lanka and Puerto Rico, all obtained at least over 70 years ago. Although scarce, other species of Colletotrichum have been recorded from Piper, raising serious concerns about the conservation status of Colletotrichum piperis and suggesting that it may no longer exist in nature.

Colletotrichum plurivorum Damm, Alizadeh and Toy. Sato, Stud. Mycol. 92: 1 (2019)

Colletotrichum plurivorum was recently described by Damm et al. (2019) accommodating fungi previously belonging to C. sichuanensis but regarding C. cliviicola as a distinct species, contrary to the study by Douanla-Meli et al. (2018). Other recent works added further reports of Colletotrichum plurivorum, being this species currently known from: chilli (Capsicum annuum, Solanaceae) in China (as Colletotrichum sichuanensis; Liu et al. 2016c) and Thailand (De Silva et al. 2019); papaya (Carica papaya, Caricaceae) in China and Mexico (Sun et al. 2019b; García-Estrada et al. 2020); lemon (Citrus limon, Rutaceae) in Vietnam (Damm et al. 2019); coffee (Coffea sp., Rubiaceae) in Vietnam (Damm et al. 2019); soybean (Glycine max, Fabaceae) in Myanmar (Zaw et al. 2020); cotton (Gossypium sp., Malvaceae) in Brazil (Damm et al. 2019); cassava (Manihot esculenta, Euphorbiaceae) in Brazil (as Colletotrichum sichuanensis; Oliveira et al. 2020) and China (Liu et al. 2019a); Myrianthus arboreus (Urticaceae) in Cameroon (Damm et al. 2019); lima bean (Phaseolus lunatus, Fabaceae) in Benin and Brazil (as C. sichuanensis) and common bean (P. vulgaris) in Iran (Cavalcante et al. 2018; Damm et al. 2019); Pyrus bretschneideri (Rosaceae) in China (Fu et al. 2019); peace lily (Spathiphyllum wallisii, Araceae) in Iran (Damm et al. 2019). Colletotrichum plurivorum is thus a cosmopolitan and polyphagous fungus (Supplementary data 13, panel C), found on numerous agricultural crops. The numerous recent reports suggest that this fungus may be expanding and further occurrence notices are expected to arise in the near future.

Colletotrichum sojae Damm and Alizadeh, Stud. Mycol. 92: 35 (2019)

Specimens identified as Colletotrichum sojae have been collected since 1980 up to present days from soybean (Glycine max, Fabaceae) in Iran, Italy, Serbia, and the USA, but also from other Fabaceae such as alfalfa (Medicago sativa) in the USA, common bean (Phaseolus vulgaris) in Iran and cowpea (Vigna unguiculata) also in Iran (Damm et al. 2019) (Supplementary data 13, panel D). Recently the fungus was reported from Panax quinquefolium (Araliaceae) in China (Guan et al. 2021). Additional surveys are likely to clarify the host range, pathological relevance and geographic distribution of Colletotrichum sojae.

Colletotrichum vittalense Damm, Stud. Mycol. 92: 38 (2019)

Colletotrichum vittalense is a taxon of obscure existence. It is known from two isolates collected nearly one century ago, one from cacao (Theobroma cacao) in India and the other from an unspecified Orchidaceae plant from an unknown location (Damm et al. 2019). Several species of Colletotrichum are known from cacao and orchids. No other fungus clustering in C. vittalense have been documented in spite of extensive studies on both hosts, suggesting that this taxon may be extinct.

The spaethianum species complex

The spaethianum species complex was first described by Cannon et al. (2012) as an aggregate containing five species, four of which are associated with petaloid monocot plants, and none appears to have economic importance. The spaethianum is as a sister group to the graminicola complex. This complex was recognised as a distinct assemblage by Damm et al. (2009) in their work on Colletotrichum with curved conidia associated with non-grass species. Since it was firstly introduced, more species belonging to this group have been described, reaching nine accepted species (Fig. 16). Overall members of this group have been associated with 37 species belonging to 28 genera, mostly monocots (65%).

Fig. 16

Bayesian inference phylogenetic tree of the spaethianum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, his3, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum bletillae G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 144 (2013)

There is a single record for Colletotrichum bletillae, collected as an endophyte from Bletilla ochracea (Orchidaceae) in China in 2006 (Tao et al. 2013). The authors refer 17 different endophytic Colletotrichum species in the host species, thus rendering the conservation status C. bletillae of great concern.

Colletotrichum guizhouense G. Tao, Zuo Y. Liu and L. Cai, Fungal Divers. 61: 152 (2013)

The species Colletotrichum guizhouense was designated to accommodate fungi occurring as endophytes of Bletilla ochracea (Orchidaceae) in China (Tao et al. 2013). Subsequently the fungus was identified as an endophyte on Huperzia phlegmaria (=Phlegmariurus phlegmaria, Lycopodiaceae) in China exhibiting pharmaceutical interest. There are numerous species of Colletotrichum occurring on Bletilla spp., rendering the conservation status of C. guizhouense of concern.

Colletotrichum incanum H.C. Yang, J.S. Haudenshield and G.L. Hartman, Mycologia 106: 38 (2014)

The species Colletotrichum incanum was defined based on isolates obtained from diseased soybean (Glycine max) petioles in the USA (Yang et al. 2014) and subsequently reported from Capsicum sp. in China (Diao et al. 2017). The current pathological relevance, geographic distribution and conservation status of C. incanum require further investigation.

Colletotrichum lilii Plakidas ex Boerema and Hamers, Neth.Jl Pl. Path. 94: 12 (1988)

Colletotrichum lilii is recurrently found associated to the black scale disease of Lilium (Liliaceae) bulbs. It has been reported from the USA, the Netherlands and Japan (Damm et al. 2009), and more recently from Russia (Nikitin et al. 2018). Although seldom reported, this pathogen seems to be present in different parts of the world. Nevertheless, the presence of other species of Colletotrichum in Lilium suggests further surveys to ascertain the conservation status of C. lilii.

Colletotrichum liriopes Damm, P.F. Cannon and Crous, Fungal Divers. 39: 71 (2009)

The species Colletotrichum liriopes was defined based on fungi isolated from Liriope muscari (Asparagaceae) in Mexico (Damm et al. 2009) and subsequently enlarged with fungi obtained from the Orchidaceae Eria coronaria, Bletilla ochracea and Pleione bulbocodioides in China (Yang et al. 2012b; Tao et al. 2013), the Asteraceae Erigeron philadelphicus and Laphangium affine (=Gnaphalium affine) in Japan (Sato et al. 2015), the Asparagaceae Rohdea japonica in Japan, Korea and the USA (Kwon and Kim 2013; Sato et al. 2015; Trigiano et al. 2018), Ophiopogon japonicus in China (Wang and Wang 2021) and Liriope cymbidiomorpha and L. spicata in China and L. muscari in Korea (Oo and Oh 2017b; Chen et al. 2019c; Yang et al. 2020), as well as from Hemerocallis fulva (Xanthorrhoeaceae) in China (Yang et al. 2012b), Fagopyrum esculentum (Polygonaceae) in China (Chen et al. 2021) and Rumex acetosa (Polygonaceae) in Japan (Sato et al. 2015). Colletotrichum liriopes is thus a fungus that has been recurrently reported in recent years, mostly from Asparagaceae and Orchidaceae in Asia (Supplementary data 14, panel A).

Colletotrichum riograndense D.M. Macedo, R.W. Barreto, O.L. Pereira and B.S. Weir, Autralasian Plant Pathol. 45: 49 (2016)

Colletotrichum riograndense is known from a single record obtained from Tradescantia viz. fluminensis (Commelinaceae) leaves in Brazil in 2008 (Macedo et al. 2016). Although there are no other species of Colletotrichum recorded from Tradescantia, the absence of additional records of C. riograndense raises severe concerns about its conservation status.

Colletotrichum spaethianum (Allesch.) Damm, P.F. Cannon and Crous, Fungal Divers. 39: 74 (2009)

Colletotrichum spaethianum is known mostly from China, Korea and Japan, but it has been reported also from Brazil, Germany and India (Supplementary data 14, panel B), from several hosts: Allium fistulosum and A. ledebourianum (Amaryllidaceae) (Sato et al. 2015; Santana et al. 2016; Salunkhe et al. 2018a); Anemarrhena asphodeloides (Asparagaceae) (Okorley et al. 2019); Atractylodes japonica (Asteraceae) (Guan et al. 2018); Convallaria keiskei (Asparagaceae) (Ahn et al. 2017); Crinum latifolium (Amaryllidaceae) (Sato et al. 2015); Dianthus chinensis (Caryophyllaceae) (Sato et al. 2015); Hemerocallis citrina, H. flava and H. fulva (Xanthorrhoeaceae) (Yang et al. 2012b; Vieira et al. 2014); Hosta plantaginea, H. sieboldiana and H. ventricosa (Asparagaceae) (Damm et al. 2009; Sato et al. 2015; Cheon and Jeon 2016; Sun et al. 2020a); Hymenocallis littoralis (Amaryllidaceae) (Yang et al. 2012b); Iris × germanica (Iridaceae) (Sato et al. 2015); Kniphofia northiae (Xanthorrhoeaceae) (Sato et al. 2015); Lilium spp. (Liliaceae) (Damm et al. 2009; Zhao et al. 2016b); Paris polyphylla (Melanthiaceae) (Zhong et al. 2020); Peucedanum praeruptorum (Apiaceae) (Guo et al. 2013); Phaseolus vulgaris (Fabaceae) (Yang et al. 2019b); Polygonatum cyrtonema, P. falcatum and P. odoratum (Asparagaceae) (Sato et al. 2015; Liu et al. 2020b; Ma et al. 2021). Reported mostly from Asparagales hosts, it is noteworthy that records of Colletotrichum spaethianum on eudicotyledons (Dianthus, Peucedanum and Phaseolus) have occurred recently.

Colletotrichum tofieldiae (Pat.) Damm, P.F. Cannon and Crous, Fungal Divers. 39: 77 (2009)

Colletotrichum tofieldiae has been reported either as a pathogen, a saprobe or an endophyte, on several hosts and locations (Supplementary data 14, panel C): symptomless roots of Arabidopsis thaliana (Brassicaceae) in Spain (Hacquard et al. 2016); symptomless leaves of Bletilla ochracea (Orchidaceae) in China (Tao et al. 2013); Dianthus sp. (Caryophyllaceae) in the UK (Damm et al. 2009); Grevillea crithmifolia (Proteaceae) in Australia (Shivas et al. 2016); Iris × germanica (Iridaceae) in Australia (Shivas et al. 2016); dead stem of Lupinus polyphyllus (Fabaceae) in Germany (Damm et al. 2009); Ornithogalum umbellatum (Asparagaceae) in Japan (Sato et al. 2015); dead leaves of Tofieldia sp. and T. calyculata (Tofieldiaceae) in China and Switzerland respectively (Damm et al. 2009). Colletotrichum tofieldiae is thus a fungus with varied life styles recorded from several hosts and locations, suggesting that further studies many shed additional light on its conservation status, geographical distribution and ecological relevance.

Colletotrichum verruculosum Damm, P.F. Cannon and Crous, Fungal Divers. 39: 81 (2009)

Colletotrichum verruculosum is known from a single fungus, isolated in 1951 from Crotalaria juncea (Fabaceae) in Zimbabwe (Damm et al. 2009). Although there are no other species of Colletotrichum known from Crotalaria, the prolonged absence of additional records of this fungus raises serious concerns about its conservation status.

The truncatum species complex

Introduced by Cannon et al. (2012), the truncatum complex comprised only one common species, Colletotrichum truncatum (syn: C. capsici; Damm et al. 2009), which is reported as an economically destructive pathogen of many tropical crops including legumes such as soybean and solanaceous plants. As the taxonomy of this species complex has not been revised recently and besides the fact that this complex is quite small and encompasses four species (Fig. 17), its taxonomy is still confused and challenging for the most. An example is provided by C. corchorum-capsularis, a pathogen of Corchorus capsularis in China (Niu et al. 2016b): as no accurate dried type specimen was listed, this species has not been recognised as a reliable species. Another example is provided by Colletotrichum jasminigenum: the cal, gs, tub2 and ITS sequences for the type strain of this species place it in the truncatum complex (no differences to C. truncatum) but the act and gapdh sequences place it in the gloeosporioides complex, suggesting that this species (containing a single isolate) is an artifact and does not exist (as detailed in “Geographical distribution of Colletotrichum occurrences” section). Overall members of this complex have been associated with 56 species belonging to 48 genera (23% monocots and 77% eudicots). Interestingly two different species of this clade have been reported as opportunistic human pathogens, C. truncatum and C. fusiforme.

Fig. 17

Bayesian inference phylogenetic tree of the truncatum species complex. The tree was reconstructed from a combined multi-locus sequence alignment (ITS, gapdh, chs-1, act and tub2). For each locus the alignment was performed with MAFFT v7.450 (Katoh and Standley 2013), exported to MEGA7 (Kumar et al. 2016) and the best-fit substitution model calculated. Phylogenetic analyses were performed with FastTree2 v2.1.10 (Price et al. 2010) and MrBayes 3.2.6 (Ronquist et al. 2012). Bayesian posterior probability (BPP) and Maximum-Likelihood (ML) bootstrap values (above 0.50) are reported next to the node; thicker branches represent node with BPP = 1.00 and ML = 100. The scale bar represents the number of expected substitutions per site. GenBank accession numbers are listed in Supplementary file 1

Colletotrichum acidae Samarak. and K.D. Hyde, Mycosphere 9: 587 (2018)

The single isolate belonging to Colletotrichum acidae was obtained from a dead rachis of Phyllanthus acidus (Phyllanthaceae) in Thailand in 2017 and treated as saprobe (Samarakoon et al. 2018), although there are no studies on putative pathogenicity to its host. The host plant, gooseberry tree, is widely cultivated as a fruit tree in the tropics. The abundance, pathological relevance and conservation status of this species remains to be investigated.

Colletotrichum curcumae (Syd. and P. Syd.) E.J. Butler and Bisby, Fungi of India: 153 (1931)

The species Colletotrichum curcumae was designated based on two isolates collected from Curcuma longa (Zingiberaceae) in India in 1912 and 1984 (Damm et al. 2009). More recently, in 2012, the fungus was identified as the causal agent of leaf spot symptoms on Curcuma wenyujin in China (Li et al. 2016d). There seems to be a biunivocal relationship between Colletotrichum curcumae and Curcuma.

Colletotrichum fusiforme Jayawardena, Bhat, Tangthirasunun and K.D. Hyde, Fungal Divers. 75: 158 (2015)

Colletotrichum fusiforme is known from a single isolate collected in Thailand in 2012 on a dead leaf of an unknown plant (Ariyawansa et al. 2015). Hung et al. (2020) reported fungi associated with human eye keratitis similar to C. fusiforme, treating these as genetics variants of C. fusiforme or putatively as new species. Under this scenario, the conservation status of C. fusiforme is of great concern.

Colletotrichum truncatum (Schwein.) Andrus and W.D. Moore, Phytopathology 25: 121 (1935)

Colletotrichum truncatum is most noticed as causing anthracnose of economical relevance on Fabaceae and Solanaceae (Damm et al. 2009). In the past decade, the fungus was recorded from: the Amaranthaceae Salsola komarovii (Sato et al. 2015); the Amaryllidaceae Allium angulosum and A. fistulosum (Matos et al. 2017; Salunkhe et al. 2018b), Hippeastrum × hybridum (Sato et al. 2015) and Hymenocallis sp. (Hyde et al. 2018); the Apocynaceae Mandevilla sp. (Watanabe et al. 2016) and Plumeria rubra (Sato et al. 2015); the Araceae Alocasia macrorrhizos (Ben et al. 2020), Dieffenbachia sp. and Syngonium sp. (Sato et al. 2015); the Asparagaceae Dracaena braunii (Liu et al. 2019b), Polianthes tuberosa (Mahadevakumar et al. 2019) and Sansevieria sp. (Sato et al. 2015); the Asteraceae Dendranthema grandiflorum (Sato et al. 2015), Helianthus annuus and Xanthium strumarium (as X. occidentale) (Shivas et al. 2016); the Basellaceae Basella alba (Yang et al. 2018); the Begoniaceae Begonia × semperflorens (Zhai et al. 2018); the Brassicaceae Brassica rapa (as B. parachinensis) and B. rapa var. chinensis (Sato et al. 2015; He et al. 2016); the Cactaceae Hylocereus undatus (Guo et al. 2014b; Sato et al. 2015; Ngoc et al. 2018); the Caricaceae Carica papaya (Sato et al. 2015; Aktaruzzaman et al. 2018; Vieira et al. 2020); the Chenopodiaceae Chenopodium quinoa (Pal and Testen 2021); the Cucurbitaceae Cucumis sativus (Sato et al. 2015); the Euphorbiaceae Euphorbia pulcherrima (Sato et al. 2015), Jatropha curcas (Ellison et al. 2015) and Manihot esculenta (Hyde et al. 2018; Machado et al. 2021b); the Fabaceae Arachis hypogaea (Damm et al. 2009; Shivas et al. 2016; Yu et al. 2020), Cicer arietinum (Mahmodi et al. 2013), Glycine max (Sato et al. 2015; Shivas et al. 2016; Rogério et al. 2019; Zaw et al. 2020), Stylosanthes hamata (Shivas et al. 2016; Hyde et al. 2018) and Vigna subterranea and V. unguiculata ssp. sesquipedalis (Sato et al. 2015; Hyde et al. 2018); the Malvaceae Abutilon theophrasti (Cong et al. 2020) and Gossypium sp. (Hyde et al. 2018); the Oleaceae Fraxinus excelsior (Davydenko et al. 2013); the Passifloraceae Passiflora edulis (Sato et al. 2015; Chen and Huang 2018); the Piperaceae Piper betle (Sun et al. 2020b); the Polygonaceae Fagopyrum esculentum (Sato et al. 2015); the Rosaceae Fragaria × ananassa (Sato et al. 2015; Bi et al. 2017a) and Prunus persica (Grabke et al. 2014); the Rutaceae Citrus flamea, C. limon and C. reticulata (Huang et al. 2013; Cheng et al. 2014; Guarnaccia et al. 2017); the Saururaceae Houttuynia cordata (Sato et al. 2015); the Solanaceae Capsicum annuum and C. frutescens (Damm et al. 2009; Sato et al. 2015; Liu et al. 2016c; Diao et al. 2017; De Silva et al. 2017a; Tariq et al. 2017; Oo and Oh 2020) and Solanum lycopersicum and S. melogena (Diao et al. 2014; Sato et al. 2015; Saini et al. 2017b; Hyde et al. 2018; Almaraz-Sánchez et al. 2019); the Theaceae Camellia sinensis (Wang et al. 2016); the Violaceae Viola odorata (Katoch et al. 2017); the Vitaceae Vitis labruscana × V. vinifera (Zhang et al. 2018c); human eye (Valenzuela-Lopez et al. 2018). Colletotrichum truncatum is thus a polyphagous and cosmopolitan fungus, with the most part of recent records being reported from Asia (Supplementary data 15).

Singleton species

Another 14 species of Colletotrichum do not cluster with any other species or species complexes and are therefore considered as singleton species.

Colletotrichum bambusicola C.L. Hou & Q.T. Wang, Mycologia 113: 450-458 (2021)

The species Colletotrichum bambusicola was described based on fungi identified as endophytes on seeds of the bamboos Brachystachyum densiflorum, Phyllostachys aureosulcata, Ph. edulis and Ph. sulphurea on several locations in China (Wang et al. 2021b). Considering the endophytic nature of these fungi and the large number of species of Colletotrichum on bamboos, the conservation status of this species should be under surveillance.

Colletotrichum chlorophyti S. Chandra and Tandon, Curr. Sci. 34: 565 (1965)

Colletotrichum chlorophyti is known from Chlorophytum sp. (Asparagaceae) in India, Stylosanthes hamata (Fabaceae) in Australia (Damm et al. 2009), soybean (Glycine max; Fabaceae) in the USA (Yang et al. 2012a), Moringa oleifera (Moringaceae) and Atractylodes lancea (as A. chinensis, Asteraceae) in China (Cai et al. 2016b; Sun et al. 2019a). Colletotrichum chlorophyti was also recently identified from a human eye associated to keratomycosis (Paniz-Mondolfi et al. 2021). Colletotrichum chlorophyti is thus a polyphagous and pluricontinental fungus (Supplementary data 16, panel A), but its ecological status and pathological relevance must be further clarified.

Colletotrichum citrus-medicae Qian Zhang, Yong Wang bis, Jayawardena & K.D. Hyde, in Hyde et al., Fungal Divers. 103: 219-271 (2020)

Colletotrichum citrus-medicae was recently described based on isolates collected at a single location in China, associated to spots on Citrus medica leaves (Hyde et al. 2020c). The vast number of species of Colletotrichum occurring on citrus calls for attention concerning the conservation status of C. citrus-medicae.

Colletotrichum coccodes (Wallr.) S. Hughes, Can. J. Bot. 36: 754 (1958)

Recorded from numerous hosts in diverse families, C. coccodes is most noticeable as a pathogen of Solanum tuberosum and S. lycopersicum, causing potato black dot and tomato anthracnose (Liu et al. 2011). Recent notices from different regions indicate its widespread presence worldwide (Çakır et al. 2019; Pérez-Mora et al. 2020) (Supplementary data 16, panel B).

Colletotrichum guangxiense C.L. Hou & Q.T. Wang, Mycologia 113: 450-458 (2021)

The species Colletotrichum guangxiense was described based on fungi identified as endophytes on seeds of the bamboo Phyllostachys edulis in China (Wang et al. 2021b). Considering the endophytic nature of this fungus and the large number of species of Colletotrichum on bamboos, the conservation status of this species should be under surveillance.

Colletotrichum hsienjenchang I. Hino and Hidaka, Bull. Miyazaki Coll. Agric. Forest. 6: 93-99 (1934)

This species is associated to bamboos (Phyllostachys spp., Poaceae) and recorded from Japan and China since 1934, with the most recent record dating from 2011 (Sato et al. 2012). The species is considered rare, although no other species of Colletotrichum are recorded from Phyllostachys, prompting further studies on these hosts to ascertain the current distribution and conservation status of C. hsienjenchang.

Colletotrichum metake Sacc., Annls Mycol. 6: 557 (1908)

Colletotrichum metake was described as a fungus inhabiting an unspecified bamboo species in Italy in 1908 and is currently found on the Poaceae Pleioblastus simonii in Japan (Sato et al. 2012) and Chimonobambusa quadrangularis in China (Wang et al. 2021b). The species is considered rare (Sato et al. 2012) and further surveys are important to ascertain its conservation status in the future.

Colletotrichum nigrum Ellis and Halst., in Halsted, New Jersey Agric. Coll. Exp. Sta. Bull.: 297 (1895)

Colletotrichum nigrum was described as a pathogen of chilli (Capsicum annuum, Solanaceae) and subsequently reported from chicory (Cichorium intybus, Asteraceae), strawberry (Fragaria × ananassa, Rosaceae), sunflower (Helianthus tuberosus, Asteraceae), lentil (Lens culinaris, Fabaceae) and tomato (Solanum lycopersicum, Solanaceae) in different parts of the world (Rivera et al. 2016) (Supplementary data 16, panel C). Several other species of Colletotrichum have been identified as causal agents of anthracnose on each of these hosts (and no reports on chicory) in recent years, whereas recent reports of C. nigrum are quite seldom: it was reported associated to tomato anthracnose in the USA in 2013 (Rivera et al. 2016), to autumn sage (Salvia greggii, Lamiaceae) in Italy in 2015 (Guarnaccia et al. 2019) and to quinoa (Chenopodium quinoa, Chenopodiaceae) in the USA in 2019 (Pal and Testen 2021). The current pathological relevance of Colletotrichum nigrum is uncertain and its conservation status is of concern.

Colletotrichum orchidophilum Damm, P.F. Cannon and Crous, Stud. Mycol. 73: 83 (2012)

Colletotrichum orchidophilum was described from fungi isolated from the Orchidaceae × Ascocenda sp. in the USA, Cycnoches aureum in Panama, Dendrobium sp. in Thailand and the USA and Phalaenopsis sp. in the UK (Damm et al. 2012a; Ma et al. 2018). Such seldom reports, along with the large number of species of Colletotrichum occurring on orchids, raise concern on the conservation status of C. orchidophilum.

Colletotrichum pseudoacutatum Damm, P.F Cannon and Crous, Stud. Mycol. 73: 91 (2012)

The species Colletotrichum pseudoacutatum was described based on a single isolate, obtained from Pinus radiata (Pinaceae) in Chile in 1976 (Damm et al. 2012a). Recently the species was rediscovered associated to anthracnose of Syzygium jambos (Myrtaceae) in Brazil (Soares et al. 2017). In spite of the seldom records, this recent finding suggests that the species may be currently occurring in nature at least in South America, but further studies are needed to account for its pathological relevance, geographic distribution and conservation status.

Colletotrichum pyrifoliae M. Fu and G.P. Wang, Persoonia 42: 25 (2019)

Colletotrichum pyrifoliae is known only from a single isolate collected from Pyrus pyrifolia (Rosaceae) in China in 2016 (Fu et al. 2019). The absence of additional records for this fungus and the large number of species of Colletotrichum known from Pyrus raise high concern on the conservation status of C. pyrifoliae.

Colletotrichum rusci Damm, P.F. Cannon and Crous, Fungal Divers. 39: 72 (2009)

Colletotrichum rusci was described based on a single isolate obtained from an unspecified species of Ruscus (Asparagaceae) in Italy in 2002 (Damm et al. 2009). No other species of Colletotrichum have been reported from Ruscus. The absence of any further occurrences of C. rusci raises severe concerns about its conservation status.

Colletotrichum sydowii Damm, Stud. Mycol. 86: 99 (2017)

Colletotrichum sydowii is known from a single isolate obtained from an unspecified species of Sambucus (Adoxaceae) in China in 2011 (Marín-Felix et al. 2017). The absence of any further records for this fungus and the occurrence of other species of Colletotrichum on Sambucus raises serious concerns on the conservation status of C. sydowii.

Colletotrichum trichellum (Fr.) Duke, Trans. Br. Mycol. Soc. 13: 173 (1928)

Colletotrichum trichellum is a pathogen of ivy (Hedera spp., Araliaceae), reported from diverse parts of the world (Damm et al. 2009; Sato et al. 2015) (Supplementary data 16, panel D), although still lacking modern taxonomic treatment (Damm et al. 2009; Cannon et al. 2012). Recent records are scarce, suggesting that the conservation status of C. trichellum should be better monitored.

Synonymised and doubtful species of Colletotrichum

From the 805 species of Colletotrichum recorded in Index Fungorum, the present work lists 257 species, meaning that another 548 species are pending modern treatment or have been synonymised. Table 1 lists the species described since 2009 that are not in use as they have been subsequently synonymised.

Table 1 Species of Colletotrichum created since 2009 that have been subsequently synonymized

Additionally, the taxon Colletotrichum japonicum (Hemmi) Bedlan was named to accommodate a pathogen of Berberis aquifolium occurring in Japan (Bedlan 2012) and presumably also in Poland and Austria (Świderska-Burek 2021), but no molecular data is provided, and the taxon is pending modern taxonomic treatment.

Also, Colletotrichum jasminigenum, known from a single record obtained from Jasminum sambac (Oleaceae) in Vietnam in 2009 (Wikee et al. 2011) and placed in the truncatum complex, was described based on ITS, tub2, cal and gs sequences (HM131513, HM153770, HM131494 and HM131504 GenBank references, respectively) that are similar to those of C. truncatum, whereas the act and gapdh sequences (HM131508 and HM131499, respectively) are similar to those of C. pandanicola (gloeosporioides complex), suggesting that C. jasminigenum is an artifact and that it should not be recognised as a species.

Similarly, Colletotrichum chiangraiense reported once, from a Dendrobium sp. (Orchidaceae) root in Thailand in 2013 (Ma et al. 2018), along with other Colletotrichum species and placed by the authors in the boninense complex, is considered as an artifact, since the ITS sequence of the type strain (MF448522) places this taxon in the boninense complex, whereas the act (MH376383) and tub2 (MH351275) sequences place it in the gigasporum complex.

Geographical distribution of Colletotrichum occurrences

In this work we documented 2717 occurrences of Colletotrichum, with 25.6% of the records in China, followed by Brazil (9.4%), Australia (8.5%) and the USA (8.1%), and then by Italy, Japan, and New Zealand (4–5% each), followed by Thailand, India and the Netherlands. By continent, Asia represents 42.1% of the occurrences, followed by America (25.0%), Europe (15.6%), Oceania (12.9%) and Africa (3.6%). However, species of Colletotrichum are distributed differently, for example, C. acutatum, C. simmondsii and C. queenslandicum preferentially occur in Australia and C. aotearoa in New Zealand; C. kahawae is restricted to Africa; C. abscissum, C. chrysophilum, C. fructivorum, C. tamarilloi, C. theobromicola and C. tropicale occur mostly in America; C. godetiae (and to a certain extent, C. fioriniae and C. nymphaeae) occur more frequently in Europe (Table 2).

Table 2 Number of occurrences of Colletotrichum spp. (for species with 30 or more records in this work) per continent

Host specificity

Colletotrichum occurs mostly on dicotyledonous plants (over 77% of all host-fungus species association records), but monocotyledonous hosts are the most common in the clade grouping the caudatum, graminicola and spaethianum species complexes. Colletotrichum also occurs, although less frequently, on gymnosperms, ferns, mosses and animals.

In this work we have recorded 1358 unique host species-Colletotrichum species association records from 720 hosts (Supplementary data 1, ‘occurrences’ tab). Two members of the gloeosporioides complex, such as Colletotrichum siamense and C. gloeosporioides are the species with the largest number of host species (Table 3), inhabiting hosts from very diverse botanical families. On the other hand, several species consistently present a high degree of host specificity. These include: in the acutatum complex, Colletotrichum abscissum on Citrus sinensis, Colletotrichum laticiphilum on Hevea brasiliensis, C. lupini on Lupinus spp., C. phormii on Phormium spp. and C. tamarilloi on Solanum betaceum; in the agaves complex, C. agaves on Agave spp. and C. sansevieriae on Sansevieria trifasciata; in the boninense complex, C. petchii on Dracaena spp.; in the destructivum complex, C. lentis on Lens culinaris, C. ocimi on Ocimum basilicum and C. pisicola on Pisum sativum; in the dracaenophilum complex, C. dracaenophilum on Dracaena spp.; in the gloeosporioides complex, C. alatae on Dioscorea alata, C. arecicola on Areca catechu, C. camelliae on Camellia spp., Colletotrichum horii on Diospyros kaki, C. kahawae on Coffea arabica, Colletotrichum musae on Musa spp. and C. perseae on Persea americana; in the graminicola complex, C. eremochloae on Eremochloa ophiuroides, C. falcatum on Saccharum officinarum, C. graminicola on Zea mays and C. sublineola on Sorghum spp.; in the orbiculare complex, C. lindemuthianum on Phaseolus spp.; Colletotrichum trichellum (singleton species) on Hedera spp. Many other examples are pending further records to confirm the host specificity of such fungi. Whereas some Colletotrichum species are specific of a given host species (e.g., C. tamarilloi or C. laticiphilum), others are specific of the host genus (e.g., C. lupini or C. camelliae) and others are specific at the family level, such as: in the acutatum complex, C. carthami and C. chrysanthemi on the Asteraceae; in the boninense complex, C. cymbidiicola on the Orchidaceae; in the graminicola complex, C. cereale on the Poaceae; in the orbiculare complex, C. orbiculare on the Cucurbitaceae; in the orchidearum complex, C. sojae on the Fabaceae; C. orchidophilum (singleton species) on the Orchidaceae.

Table 3 The ten species of Colletotrichum with the larger number of host species

The gloeosporioides complex encompasses 516 Colletotrichum species-host species association records, followed by the acutatum and the boninense complexes (Table 4). The acutatum, gloeosporioides and truncatum complexes have, on average, over seven host species for each species of Colletotrichum, whereas the agaves, caudatum, dracaenophilum and graminicola have on average between one and two host species for each species of Colletotrichum. It is worth noting that most of the later complexes contain species more frequently found on monocots.

Table 4 Number of Colletotrichum species-host species combinations by complex

The Fabaceae is the family with the largest number of species hosting Colletotrichum (51 host species), followed by the Poaceae (42 hosts), and then by the Orchidaceae, Asparagaceae and Rosaceae (Table 5). Nevertheless, it is in the Rosaceae that the highest number of Colletotrichum species-host species association records is found (118), followed by the Fabaceae (87), Solanaceae (72), Rutaceae (63) and Orchidaceae (59). The Fabaceae stand out also as the family hosting the highest number of species complexes (11), followed by the Solanaceae (10) and the Asteraceae and Orchidaceae (9 each).

Table 5 Number of host species, of fungus-host combinations and number of Colletotrichum species and species complexes by host family

The Rosaceae and the Solanaceae host 41 species of Colletotrichum each, followed by the Orchidaceae and the Fabaceae (36 species), and then by the Poaceae and Rutaceae (Table 6). There are 880 unique association records between Colletotrichum species and host family, with the gloeosporioides complex representing 36.8% of such association records, followed by the acutatum complex (20.9%) and by the boninense complex (9.7%), and then by the destructivum, truncatum, spaethianum, orchidearum and dematium complexes (3–5% each). Whereas for most host families these proportions remain valid (e.g., the Anacardiaceae, Ericaceae, Lauraceae, Malvaceae, Moraceae, Myrtaceae, Oleaceae, Proteaceae, Rosaceae, Rubiaceae, Rutaceae, Solanaceae, Theaceae and Vitaceae, i.e., mostly dicots, but also the Arecaceae and Musaceae), some other families clearly have different patterns of preference concerning species complexes. The destructivum complex registers the highest number of unique species-host family association records in the Fabaceae, Asteraceae and Lamiaceae, instead of the gloeosporioides complex, whereas the destructivum and dematium complexes are the most represented in the Apiaceae. In the Euphorbiaceae, the acutatum complex is more represented than the gloeosporioides one. The situation is more heterogeneous among the monocots: the graminicola complex (followed by the caudatum complex) prevails in the Poaceae; the boninense complex is the most common in the Orchidaceae, and along with gloeosporioides in the Amaryllidaceae and with orchidearum in the Araceae; the agaves complex (along with gloeosporioides and spaethianum) is the most represented in the Asparagaceae. Although supported on limited numbers, the acutatum and boninense complexes are more frequent on the gymnosperms than the gloeosporioides complex.

Table 6 Number of unique association records between Colletotrichum species and host families per species complex and for the most represented families

Abundance and conservation of Colletotrichum spp.

Colletotrichum occur on a large number of host and locations, with new host and locations frequently reported. Over the last decade, Colletotrichum became consolidated as the second most referred genus in terms of number of Plant Disease Notes published in the journal Plant Disease, raising from an average of 17.7 Notes per year during 2010–2015 to 48 Notes per year during 2016–2020, second only to Fusarium (Fig. 18).

Fig. 18

Number of Plant Disease Notes published in the journal Plant Disease (section “Diseases Caused by Fungi and Fungus-Like Organisms”) for the five most reported genera, by year of publication

As discussed in the previous sections, several species of Colletotrichum occur on multiple hosts and in diverse locations, whereas others are host specific and/or geographically confined, but still are common on those hosts and/or regions. Being mostly plant pathogens, some of these fungi cause losses of economical relevance on agricultural crops, thus requiring control. Other species however are uncommon or even rare, and may incur in conservation problems. From the 257 species of Colletotrichum listed in this work, 101 (i.e., 39.3% of all species) have been recorded only once and another 44 have been recorded only twice, meaning that only 44.0% of the 257 species recognised have been recorded three times or more. In fact, the 10% more common species represent 67.2% of all occurrences.

Many of these unfrequent species have been recorded recently and it is therefore plausible that additional occurrences arise in the future. Until then, however, such species must be regarded as potentially endangered. The number of occurrences and year of description of recent but unfrequent species are presented in Table 7. For instance, Colletotrichum yunnanense was described in 2007 based on one occurrence but never recorded again and C. fructivorum, although recorded nine times, was never again documented besides its original description in 2013.

Table 7 Number of species of Colletotrichum recently described but seldomly reported, according to year of publication of the taxon and to the number of occurrences recorded in this work

In this work we have considered 88 species as common, meaning that the remaining 169 species are of seldom occurrence. Among these, we have considered 42 species as threatened, either because they have not been recorded inspite of recurrent surveys or because they are rare and have been described in circumstances that inpair conducting additional surveys. The list of the 42 species considered as threatened is presented in Table 8, arranged by species complexes and containing information related to each species.

Table 8 List of 42 species of Colletotrichum considered as threatened

Another 127 species are treated as ‘data deficient’ (Table 9) and further surveys are needed to ascertain their conservation status, host range and geographic distribution, including unfrequent species that have been recently described along with others not recorded for decades but from hosts not commonly surveyed.

Table 9 List of 127 species of Colletotrichum treated as ‘data defficient’

Altogether, from the 257 species of Colletotrichum, 127 are classified as ‘data deficient’ and 42 as ‘threatened’, meaning that 169 species (65.8% of total) are not known to be firmly established in nature. The remaining 88 species are considered ‘common’ and generally occur on multiple hosts or in single hosts but in multiple locations. The relative proportion of these three categories varies according to the species complex, with threatened species representing a large fraction of the species in the orchidearum and gigasporum complexes, and common species more frequently found in the gloeosporioides, spaethianum, acutatum, orchidearum and destructivum complexes (Fig. 19).

Fig. 19

Relative and absolute frequency of the number of Colletotrichum species considered “common”, “data deficient” and “threatened” in each species complex

Under the current knowledge 130 Colletotrichum species are known only from a single country and can therefore considered as endemisms. By country, these are:

• Australia—C. brisbanense and C. cairnsense (acutatum complex), C. alcornii (caudatum complex), C. tanaceti (destructivum complex) and C. australianum, C. cobbittiense and C. xanthorrhoeae (gloeosporioides complex);

• Brazil—C. paranaense (acutatum complex), C. brasiliense (boninense complex), C. serranegrense (gigasporum complex), C. bidentis (orbiculare complex) and C. riograndense (spaethianum complex);

• Canada—C. tebeestii (orbiculare complex);

• Chile—C. arboricola and C. roseum (acutatum complex);

• China—C. eriobotryae and C. miaoliense (acutatum complex), C. chongqingense (boninense complex), C. caudisporum, C. duyunense and C. ochraceae (caudatum complex), C. hemerocallidis and C. jinshuiense (dematium complex), C. atractylodicola and C. neorubicola (destructivum complex), C. excelsum-altitudinum, C. tongrenense and C. yunnanense (dracaenophilum complex), C. jishouense and C. pseudomajus (gigasporum complex), C. arecicola, C. changpingense, C. conoides, C. cycadis, C. hebeiense, C. henanense, C. pseudotheobromicola, C. tainanense, C. wuxiense, C. xishuangbannaense and C. yulongense (gloeosporioides complex), C. endophytum and C. hainanense (graminicola complex), C. liaoningense (magnum complex), C. bletillae and C. guizhouense (spaethianum complex) and C. citrus-medicae, C. bambusicola, C. guangxiense, C. sydowii and C. pyrifoliae (singleton species);

• Colombia—C. annellatum and C. colombiense (boninense complex);

• Costa Rica—C. costaricense (acutatum complex), C. radicis (gigasporum complex) and C. cacao (magnum complex);

• Dominica—C. cuscutae (acutatum complex);

• Germany—C. oncidii (boninense complex) and C. coelogynes (dracaenophilum complex);

• Greece—C. helleniense (gloeosporioides complex);

• India—C. guajavae (acutatum complex) and C. vittalense (orchidearum);

• Indonesia—C. indonesiense and C. javanense (acutatum complex) and C. makassarense (gloeosporioides complex);

• Italy – C. lauri (acutatum complex), C. sambucicola and C. sonchicola (dematium complex), C. orchidis (destructivum complex), C. grevilleae, C. hederiicola, C. hystricis and C. psidii (gloeosporioides complex) and C. rusci (singleton species);

• Japan—C. camelliae-japonicae (boninense complex), C. zoysiae (caudatum complex), C. shisoi (destructivum complex) and C. echinochloae and C. paspali (graminicola complex);

• Korea—C. kakiivorum (dematium complex);

• Netherlands—C. cosmi (acutatum complex), C. anthrisci (dematium complex) and C. utrechtense (destructivum complex);

• New Zealand—C. acerbum and C. johnstonii (acutatum complex), C. beeveri, C. constrictum, C. dacrycarpi, C. novae-zelandiae and C. torulosum (boninense complex), C. antirrhinicola (dematium complex) and C. ti (gloeosporioides complex);

• Nigeria—C. vignae (destructivum complex);

• Panama—C. merremiae and C. panamense (magnum complex);

• Portugal—C. feijoicola (boninense complex);

• Russia—C. eryngiicola, C. insertae, C. menispermi, C. parthenocissicola, C. quinquefoliae and C. sedi (dematium complex);

• Saint Lucia—C. paxtonii (acutatum complex);

• South Africa—C. euphorbiae, C. ledebouriae and C. neosansevieriae (agaves complex), C. pleopeltidis (destructivum complex) and C. proteae (gloeosporioides complex);

• Thailand—C. doitungense (boninense complex), C. cariniferi and C. parallelophorum (dracaenophilum complex), C. artocarpicola, C. chiangmaiense, C. dracaenigenum and C. pandanicola (gloeosporioides complex) and C. acidae (truncatum complex);

• Trinidad and Tobago—C. lobatum (magnum complex);

• UK—C. kniphofiae (acutatum complex);

• USA—C. baltimorense, C. caudatum and C. somersetense (caudatum complex), C. fructi (dematium complex), C. rhexiae and C. temperatum (gloeosporioides complex), C. navitas (graminicola complex) and C. sidae (orbiculare complex);

• Vietnam—C. walleri (acutatum complex), C. condaoense (boninense complex) and C. vietnamense (gigasporum complex);

• Zimbabwe—C. verruculosum (spaethianum complex).

Conclusions, implications and future perspectives

In this work we have listed 257 species of Colletotrichum, clustering in 15 species complexes (some species are not assigned to any complex). Species complexes in Colletotrichum (as well as in other genera that have also experienced a recent rapid increase in the number of species recognised) gained high practical relevance but, anachronistically, they lack formal definition. For instance, when referring to C. abscissum, authors frequently use expressions such as “Colletotrichum abscissum of the acutatum complex”, which is a complicated and unfriendly designation. In the future, and as the phylogeny of Colletotrichum progresses to a mature and stable condition, species complexes may gain formal taxonomic value and become infra-generic taxa.

In this work we have also highlighted difficulties and challenges regarding species delimitation and identification. Two species have been rejected as they turned out to be defined based on chimeric sequences that, once concatenated, suggested these to be novel taxa, but individually, were identical to those of previously described species. When describing new species it is fundamental that the sequence of each gene is compared to sequences of the type strains of existing species and not just the concatenated sequence of diverse genes. The employment of multiple loci in taxonomy is highly recommended (e.g., Lücking et al. 2020; Aime et al. 2021) but the examples provided here emphatise the relevance of analysing each locus individually. Chimeric multiloci sequences are quite perverse, as they affect the tree topology and, when applied, the time calibration. Depositing fungal cultures in living collections (but also providing accurate information on their substrates and collection location in nature) is fundamental for current and future understanding of these fungi (as detailed by Aime et al. 2021). It is expected that fungal whole genome sequencing (WGS) will soon become easier and cheaper, and this will allow most research laboratories to start in-house WGS projects on a daily basis. Providing genome data for type strains will soon become good practice that should be implemented when describing new species. The use of WGS will support the identification and the description of new species by:

• extended MLST approaches such as phylogenomic analyses;

• quantification of genetic interchange between taxonomic groups; this will also help resolve the situation of chimeric strains or hybrids (e.g. by analysing genomic portion or loci into different datasets established by congruent tree topologies;

• time estimation of genetic isolation;

• the identification of the genetic factors involved in important biological processes such as those linked with the speciation process.

Nevertheless, strains from new species should also be characterised considering their life styles, with pathogenicity/host range/substrate usage studies being highly recommended to be included along the description of novel species.

In this work we have considered a total of 2711 occurrence reports of Colletotrichum strains that could be confidently traced to species under current taxonomic criteria. When revising literatures from the last 10 years we were particularly caruful in scrutinising the use of multilocus analyses (when necessary) for identification by comparison to sequences from the type strains of the candidate species. In several circumstances we did not considered identification reports that were based on single gene information (when more than one gene was required to identify a given species) nor those based only on BLAST identification. BLAST searches are adequate for preliminary identification of candidate target species, but then the sequence(s) of the strain to be identified should be compared to the sequences of the type strains of the several species that are phylogenetically close to the candidate target species identified in the BLAST search. A recent analysis showed that ca. 30% of ITS sequences available in nucleotide sequence databases are associated to a wrong fungal taxon (Hofstetter et al. 2019) and this holds true in the Colletotrichum genus (Boufleur et al. 2021). Here (Supplemental Data 1) we present the most recent table listing species of Colletotrichum and the respective GenBank references for ITS, gapdh, chs-1, act and tub2 sequences. Ensuring that identification of strains is performed scrupulously is fundamental for a stable and meaningful utilisation of species in Colletotrichum, both from taxonomical and plant pathology perspectives.

Whereas conservation status of animal and plant species are of major concern, fungi have deserved much less attention, and still mostly focused on macrofungi and lichens. The IUCN Red List of Threatened species (www.iucnredlist.org) lists the conservation status of 343 fungal species (as compared to ca. 43,500 plant and 76,500 animal species), including 62 Ascomycota among which only seven Sordariomycetes, none of which from the Glomerellales. Microfungi, and plant pathogens in particular, are notoriously absent from such lists. The IUCN Red List system is recognised as the most authoritative for the evaluation of biological conservation and criteria have been adapted to use in fungi (Dahlberg and Mueller 2011) and Conservation Mycology has been recently recognised as a discipline within Conservation Biology (May et al. 2018), but macrofungi take most of the attention and plant pathology was clearly excluded from fungal conservation (Dahlberg et al. 2010), as fungal plant pathogens fail to meet the criteria according to which fungi can be readily integrated into conservation (Heilmann-Clausen et al. 2014). The conservation of microfungi, with emphasis on those that are not directly observable because of their endophytic or otherwise latent nature, has been subject of attention recently (Blackwell and Vega 2018). Metagenomics analyses of fungal communities in given ecosystems can provide the means to obtain abundant occurrence data (Blackwell and Vega 2018), but current approaches, based on DNA barcode genes of large phylogenetic spectrum (Hibbett et al. 2016), do not enable the discrimination of several species of Colletotrichum, for which specific markers are needed. In other words, under current delimitation, species of Colletotrichum are not directly identifiable in nature nor can be identified based on broad (i.e. ITS-based) metagenomics approaches. Ascertaining whether a species of Colletotrichum is threatened thus faces additional problems to those raised by Blackwell and Vega (2018). In this work we have opted to use informal classifications of the conservation status of Colletotrichum species as the employment of criteria as defined by Dahlberg and Mueller (2011) is not possible for most species. Recently Aime et al. (2021) provided updated guidelines on “How to publish a new fungal species or name”, among which stand the recommendation to “include multiple collections of specimens or cultured isolates when describing a new species”, in sharp contrast with the fact that 145 of the currently recognised species of Colletotrichum (i.e., 56.4% of the 257 species) have been recorded no more that two times from nature. Conservation is structurally based on the concept of species, but the threshold for the classification of fungal species has varied strongly over the last decades, with the history of Colletotrichum taxonomy being paradigmatic of this. Conservation of Colletotrichum species is thus critically dependent on a stable taxonomic framework. Species denoted as “data deficient” in this work may in fact turn out to be common and even of pathological relevance, but further monitoring is needed, joining efforts between Conservation Mycology and Plant Pathology, an area in which the generalisation of WGS approaches may provide a decisive help. The present study, providing a comprehensive review of accepted species of Colletotrichum and their clustering into complexes, along with the compilation of occurrence data, provides a basis for subsequent studies linking taxonomy and conservation of Colletotrichum species and on the role of these fungi as plant pathogens of major agricultural crops worldwide.