Taxonomy of Nematode-Trapping Fungi from Orbiliaceae, Ascomycota

Yu, ZeFen; Mo, MingHe; Zhang, Ying; Zhang, Ke-Qin

doi:10.1007/978-94-017-8730-7_3

ZeFen Yu⁴,
MingHe Mo⁴,
Ying Zhang⁴ &
…
Ke-Qin Zhang⁴

Part of the book series: Fungal Diversity Research Series ((FDRS,volume 23))

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13 Citations

Abstract

Nematode-trapping fungi of Orbiliaceae include those filamentous species forming trapping devices to prey on juveniles of nematodes. In this chapter, the taxonomic history of predatory orbiliaceous fungi is reviewed and the system of using trapping devices as the primary morphological criterion for generic delimitation is advocated. Following this taxonomic concept, keys for genera of Arthrobotrys, Drechslerella and Dactylellina, which include all reported species of predatory orbiliaceous fungi are presented. Totally, 54, 14 and 28 species from Arthrobotrys, Drechslerella and Dactylellina respectively, are morphologically described and illustrated. Known asexual-sexual connections (14) of predatory orbiliaceous fungi are summarized and their taxonomic descriptions and illustrations presented.

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Generic names in the Orbiliaceae (Orbiliomycetes) and recommendations on which names should be protected or suppressed

Article Open access 17 May 2017

Predator-prey interactions of nematode-trapping fungi and nematodes: both sides of the coin

Article 09 March 2018

13 Nematophagous Fungi

Keywords

Introduction

In various natural environments, especially in soil, there are a wide and diverse range of microorganisms that function as antagonists of nematodes and include fungi, bacteria, viruses and rickettsias (Li et al. 2000). Nematophagous fungi or nematode-destroying fungi are antagonists of nematodes, and comprise a great variety of fungi belonging to widely divergent orders and families. Based on nematicidal mechanisms, these antagonists are assigned to the groups, endoparasitic fungi, opportunistic fungi, toxic fungi or nematode-trapping fungi (Li et al. 2000). Endoparasitic fungi are regarded as obligate parasites infecting nematodes via special spores and mycelia development takes place from spores within the nematode and only the reproductive-conidiophores are externalized (Li et al. 2000). Toxic fungi refer to those producing metabolites toxic to nematodes. Opportunistic fungi can colonize nematode reproductive structures and have the ability to seriously affect their reproductive capabilities (Siddiqui and Mahmood 1996).

Nematode-trapping fungi capture nematodes by trapping devices produced from the vegetative mycelia. The trap types reported include adhesive networks, adhesive knobs, constricting rings, non-constricting rings, adhesive branches, undifferentiated or unmodified adhesive hyphae, stephanocysts, spiny balls and acanthocytes (Zhang et al. 2001; Tzean and Liou 1993; Luo et al. 2004, 2007). The first five types of trap are known only to be produced by the predacious asexual morphs of Orbiliaceae of Ascomycota. Adhesive knobs are however, also formed by Zoophagus species of Zygomycetes (Li et al. 2000) and Nematoctonus species of basidiomycetes (Barron 1977).

Orbiliaceous members represent the majority of nematode-trapping fungi, which include 96 species, and are currently assigned in the asexual genera Arthrobotrys (53 species), Dactylellina (28 species) and Drechslerella (14 species). Traps of adhesive hyphae are restricted to the genera Stylopage and Cystopage of Zygomycetes (Drechsler 1941), while stephanocysts is restricted to the genus Hyphoderma of basidiomycetes (Tzean and Liou 1993). Spiny balls and acanthocytes are formed respectively by the macrobasidiomycetes Coprinus comatus (Luo et al. 2004, 2007) and Stropharia rugosoannulata (Luo et al. 2006). As mentioned above, the orbiliaceous nematode-trapping are the most complex and taxonomically unsettled.

In this chapter we focus on the largest group of nematode-trapping fungi in the Ascomycota. We discuss their historical classification and the taxonomic system currently accepted. All species of orbiliaceous nematode-trapping fungi are described and illustrated. Keys to the genera Arthrobotrys, Dactylellina and Drechslerella are provided in order to facilitate the readers to compare the species features. Furthermore, asexual-sexual state connections of the orbiliaceous nematode-trapping fungi are discussed in species descriptions and illustrations.

Systematics of Nematode-Trapping Fungi

Asexual nematode-trapping hyphomycetous fungi belong to a predatory fungal lineage. Distinctive trapping devices such as adhesive hyphae, adhesive knobs, adhesive networks, constricting rings, and non-constricting rings develop from extensions of the mycelia (Barron 1977). The trapping devices enable capture and cause subsequent mortality of nematodes, other small animals, and protozoans and the nematode-trapping fungi then obtain nutrients from these prey (Barron 1977). Since nematode-trapping fungi play an important role as antagonists of plant-parasitic and animal-parasitic nematodes, there is a great interest in using these fungi as biological control agents. Information concerning the systematic position of nematode-trapping fungi is therefore essential for understanding and exploiting them in biocontrol.

Asexual nematode-trapping hyphomycetous fungi are placed within the family Orbiliaceae (Orbiliales, Orbiliomycetes), based on morphological and molecular studies (Pfister 1997; Eriksson et al. 2003; Yu et al. 2011). The family Orbiliaceae was not known to be nematophagous until Pfister (1994) reported that a collection of Orbilia fimicola Jeng & Krug produced an Arthrobotrys asexual state named A. superba Corda. Subsequently, more and more connections between Orbiliaceae and predacious hyphomycetes have been established (Liu et al. 2005a; Mo et al. 2005a; Pfister 1995; Yu et al. 2006; Qiao et al. 2012; Li et al. 2009; Yu et al. 2009a). Connections between Orbiliaceae and other non-predacious hyphomycetous genera have also been reported (Liu et al. 2005b; Yu et al. 2009b, 2007a, 2007b, 2011; Mo et al. 2005b; Yang and Liu 2005). At least nine asexual genera have been linked to sexual Orbiliaceae species (Pfister 1997; Yu et al. 2011).

The family Orbiliaceae was shown to be monophyletic in the phylogenetic analyses of 18S and ITS rDNA sequences (Pfister 1997). Morphologically, the unique nature of the ascospores of this family, especially the inclusion of an elaborated spore body makes it distinguishable from other discomycetes. According to phylogenetic analysis of SSU rDNA sequences of 21 taxa, the Orbiliomycetes clustered near the base of the tree near the Pezizomycotina. A signature of six base pairs was consistently found in every studied species of Orbiliomycetes, which is a further evidence in the isolated position of the class (Eriksson et al. 2003). However, a range of conidial morphology is found in nematode-predacious and non-predacious asexual morphs in some phylogenetic clades. For example, in earlier classification systems, conidiophore characters were used to distinguish asexual genera. Within the series Auricolores in the sexual genus Orbilia, asexual morphs with a candelabrelloid or more simple type of conidiogenesis actually cluster, often separately, from those with an arthrobotryoid type. However, the arthrobotryoid type occurs scattered in several clades, therefore, this character does not permit a split of series Auricolores into two groups. Conidiophore types however, appear to characterize small groups within that series (Baral, pers. comm.).

Nematode-trapping fungi were formerly classified into a number of genera based on the morphology of conidia (shape, septa and size) and conidiophores (branching, modifications of the apex), such as Arthrobotrys, Dactylellina, Drechslerella, Monacrosporium, Dactylella, Gamsylella, Didymozoophaga, Trichothecium, Dactylaria, Candelabrella, Genicularia, Duddingtonia, Nematophagus, Monacrosporiella and Woroninula. This has led to a situation where species with diverse types of trapping devices have been assigned to one genus, while others with similar trapping devices can be found in different genera (Glockling and Dick 1994; Liu and Zhang 1994, 2003; Zhang et al. 1996a). The genus Arthrobotrys was first established for the type species, A. superba (Corda 1839), which is characterized by the formation of two-celled conidia on denticles in a whorled arrangement at the apex of the nodes of the simple, erect, septate conidiophore. Schenck et al. (1977) expanded the genus to include species with aseptate and multi-celled conidia. Scholler et al. (1999) subsequently limited Arthrobotrys to only those species with adhesive networks.

Subramanian (1963) erected Drechslerella for D. acrochaeta (Drechsler) Subram. based on the filiform apical appendage on its conidia. Although Liu and Zhang (1994) synonymized Drechslerella with Monacrosporium, detailed molecular analyses (Hagedorn and Scholler 1999) convinced Scholler et al. (1999) to propose new generic concepts for orbiliaceous nematode-trapping fungi based on mode of trapping device. We accept these concepts and recognize Drechslerella as characterized by forming three-celled constricting ring traps.

The genus Dactylellina was described by Morelet (1968) with Dactylellina leptospora (Drechsler) M. Morelet as type species. Species included in this genus were characterized by elongate, fusoid conidia, while microconidia and microconidiophores rarely formed. Dactylellina was recognized by Scholler et al. (1999) for species characterized by stalked adhesive knobs and included those species producing non-constricting rings. The knob-forming species of the nematode-trapping fungi however, have diverse configurations such as sessile knobs, stalked knobs, a combination of stalked knobs with non-constricting rings, or stalked knobs with proliferated knobs.

Earlier phylogenetic analyses based on ribosomal RNA (rRNA) gene sequences suggested that the trapping devices could rationalize the classification of nematode-trapping fungi (Rubner 1996). Indeed, lineages including species with stalked adhesive knobs, adhesive networks and constricting rings consistently separate from each other in molecular phylogenetic analysis. Recently, phylogenetic analyses based on ribosomal RNA (rRNA) and protein-coding gene sequences suggested that the trapping devices could serve as robust indicators of generic delimitation for these asexual fungi (Yang and Liu 2006; Ahrèn et al. 1998; Li et al. 2005; Scholler et al. 1999), different trapping devices-forming species were separated into different genetic lineages and new generic concepts of the taxonomy of predatory sexual Orbiliaceae were proposed.

Ahrén et al. (1998) found that nematode-tapping fungi clustered into three lineages: species with constricting rings, species with various adhesive structures (net, hyphae, knobs and non-constricting rings) and species have no trapping devices. Based on results obtained from morphological and molecular characters, Hagedorn and Scholler (1999) and Scholler et al. (1999) classified nematode-trapping fungi into four genera: Dactylellina characterized by stalked adhesive knobs including species characterised by non-constricting rings and stalked adhesive knobs; Gamsylella characterized by adhesive branches and unstalked knobs; Arthrobotrys characterized by adhesive networks and Drechslerella characterized by constricting rings. Furthermore, the systematic classification of nematode-trapping fungi was redefined based on phylogenies inferred from sequence analyses of 28S rDNA, 5.8S rDNA and ß-tubulin genes and an emended generic concept of nematode-trapping fungi is provided (Li et al. 2005). Arthrobotrys is characterized by adhesive networks, Dactylellina by adhesive knobs, and Drechslerella by constricting-rings. Phylogenetic placement of taxa characterized by stalked adhesive knobs and non-constricting rings is also confirmed in Dactylellina. Based on careful morphological observation of culture, Li et al. (2005) found that none of these taxa only formed unstalked adhesive knobs, which was just one temporary structure formed at the first stage in the fungus development. These unstalked knobs could then grow out to form branches, which may further change in different species, they proposed that unstalked adhesive knobs should not be treated as a unique type of trapping-device and this character should not be given taxonomic importance, and the genus Gamsylella is invalid. Species which produce unstalked adhesive knobs that grow out to form loops were transferred from Gamsylella to Dactylellina, and those which produce unstalked adhesive knobs that grow out to form networks were transferred from Gamsylella to Arthrobotrys.

Based on the combined phylogenetic analysis of rDNA and protein-coding genes and morphological studies, a hypothesis for the evolution of trapping-devices was also presented (Li et al. 2005). Predatory and non-predatory fungi appear to have been derived from non-predatory members of Orbilia. The adhesive knob is considered to be the ancestral type of trapping-device from which constricting rings and networks were derived via two pathways. In the first pathway adhesive knobs retained their adhesive material forming simple two-dimension networks, eventually forming complex three-dimension networks. In the second pathway adhesive knobs lost their adhesive materials, with their ends meeting to form non-constricting rings and they in turn formed constricting rings with three inflated-cells. Furthermore, using phylogenetic analysis of nucleotide sequences of three protein-coding genes (RNA polymerase II subunit gene, rpb2; elongation factor 1-α gene, ef1-α; and ß tubulin gene, bt) and ITS rDNA region, Yang et al. (2007) described the evolution of nematode-trapping cells of predatory fungi, they thought the initial trapping structure evolved along two lineages yielding two distinct trapping mechanisms: one developed into constricting rings and the other developed into adhesive traps. Among adhesive trapping devices, the adhesive network separated from the others early and evolved at a steady and gentle speed. The adhesive knob evolved through stalk elongation, with a final development of non constricting rings. The derived adhesive traps are indicated as a highly differentiated stage.

The non-predacious genus Dactylella was established by Grove (1884) on the basis of one species, D. minuta Grove. The genus is characterized by erect, simple, hyaline conidiophores with conidia produced singly at the apex. Conidia are ellipsoidal, fusoid or cylindrical, one-celled at first and later having 2 to many septa. This genus has been emended several times and both non-predacious and predacious fungi have been included (Subramanian 1963; Schenck et al. 1977; Zhang et al. 1994). Dactylella includes diverse taxa in morphology and behavior. There are considerable differences in conidiophore length and conidial size among species. Some species are saprotrophic, while others are oospore or nematode egg parasites (Zhang et al. 1994). Rubner (1996) revised the generic concept of Dactylella and excluded the nematode-trapping species. However, the classification has not commonly been accepted and several predacious species had been described under Dactylella (Liu and Zhang 2003). Chen et al. (2007a, b, c) emended the asexual state genus Dactylella complex based on ITS phylogeny, all the tested strains cluster into three monophylogenetic clades corresponding to three genera, e.g. Dactylella, Vermispora and a distinct group comprising species with very short conidiophores. The circumscription of Dactylella and Vermispora were emended and a new genus Brachyphoris characterized by very short conidiophores that are scarcely longer than conidia was established, which sexual states corresponding to the genus Hyalorbilia within Orbiliaceae, and other species separated into genera Dactylella and Vermispora, respectively.

Although trapping devices have proven as vital in generic delimitation of nematode-trapping fungi, species in the same genus are mainly delimited from each other by morphology of conidia and conidiophores. With more and more connections between nematode-trapping fungi and Orbiliaceae being established, phylogenetic analysis including existing asexual species indicated that conidial morphology showed only little correlation while the sexual state characters showed a high level of correlation. For instance, Arthrobotrys belong to Series Auricolores, which is defined by the ability to form adhesive networks and the asexual Trinacrium-type belong to species of Hyalorbilia, Orbilia subgenus Hemiorbilia and subgenus Orbilia (Baral, pers. comm.). Further studies are needed to set up a natural classification system including both asexual and sexual nematode-trapping fungi. In fact this is now a requirements of the International Code of Nomenclature for Algae, Fungi and Plants as two names can no longer be used for asexual and sexual morphs of the same fungus.

Key to Genera of Nematode-Trapping Fungi

1 Trapping-device a constricting ring, which consists of three inflated cells with a short, strong stalk Drechslerella

2 Trapping-device not a constricting ring, but various adhesive trapping devices 3

3 Trapping device unstalked adhesive knobs which develops into an adhesive network or adhesive networks only Arthrobotrys

4 Trapping device stalked adhesive knobs, some with non-constricting rings, or unstalked adhesive knobs which grow out to form adhesive branches and loops Dactylellina

Arthrobotrys Corda, Pracht-Fl. Eur. Schimmelbild.: 43 (1839)
Type species: Arthrobotrys superba Corda, Pracht-Fl. Eur. Schimmelbild.: 43 (1839)
Synonyms
Monacrosporium Oudem., Ned. Kruidk. Arch., Ser.2, 4: 250 (1885)
Lectotype species: Monacrosporium elegans Oudem., Ned. Kruidk. Arch., Ser.2, 4: 250 (1885), designated by Clements and Shear (1931)
Didymozoophaga Soprunov & Galiulina, Mikrobiologiya 20: 493 (1951) (invalid; Art.36; illegit. Art. 52 ICBN)
Type species: Didymozoophaga superba (Corda) Soprunov & Galiulina, Mikrobiologiya 20: 494 (1951) (invalid; Art. 36 ICBN).
Arthrobotrys superba Corda, Pracht–Fl. Eur. Schimmelbildung.: 43 (1839)
Candelabrella Rifai & R.C. Cooke, Trans. Br. mycol. Soc. 49 (1): 160 (1966)
Type species: Candelabrella javanica Rifai & R.C. Cooke, Trans. Br. Mycol. Soc. 49: 160 (1966).
Duddingtonia R.C. Cooke (1969), Trans. Br. mycol. Soc. 53 (2): 315 (1969)
Type species: Duddingtonia flagrans (Dudd.) R.C. Cooke, Trans. Br. Mycol. Soc. 53: 315 (1969)
Trichothecium flagrans Dudd., Trans. Br. Mycol. Soc. 32: 287 (1949)
Genicularia Rifai & R.C. Cooke, Trans. Br. Mycol. Soc. 49: 153 (1966) [non Genicularia Rouss. ex Desv. 1808, non de Bary 1858] (nom. illeg.;. Art. 53 ICBN; replaced by Geniculifera)
Type species: Genicularia cystosporia (Dudd.) Rifai & R.C. Cooke, Trans. Br. Mycol. Soc. 49: 154 (1966)
Trichothecium cystosporium Dudd., Trans. Br. Mycol. Soc. 34: 600 (1951a)
Nematophagus Mekht., Mikol. Fitopatol. 9 (3): 250 (1975)
Type species: Nematophagus azerbaidzhanicus Mekht., Mikol. Fitopatol. 9: 250 (1975)
Monacrosporiella Subram., Kavaka 5: 94 (1978) [1977]
Type species: Monacrosporiella megalospora (Drechsler) Subram., Kavaka 7: 94 (1977).
Dactylella megalospora Drechsler, Mycologia 46: 769 (1954)
Woroninula Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 109 (1979)
Type species: Woroninula polycephala (Drechsler) Mekht., Khishchnye nematofagovye Griby—Gifomitsety: 110 (1979)
Dactylaria polycephala Drechsler, Mycologia 29: 530 (1937)

Characteristics:

Mycelium fast growing. Hyphae septate, branching, hyaline. Conidiophores simple or branched, apex mainly with short denticles or with geniculate, candelabrelloid, or percurrent proliferations, rarely simple without modifications. Conidia either singly or in clusters at the apex of the conidiophore. Conidia holoblastic, hyaline, non-septate to multi-septate, mainly ellipsoidal, spindle-shaped or ovoid, rarely clavate, cylindrical, pyriform, or turbinate. Microconidia and microconidiophores frequently formed. Chlamydospores, when present, intercalary or rarely terminal, singly or in chains, thick-walled, sphaerical to ovoid, yellow pigmented. Sexual state when know, belonging to Orbilia. Trapping nematodes by means of adhesive networks or modified devices, with good saprotrophic capabilities. Formation of traps induced by nematodes in most species.

Key to Species of Arthrobotrys

1. Conidia produced singly at the apices of conidiophores or on subapical, lateral branches 2

1. Conidia not produced singly, often in groups 16

2. Conidia clavate, with 2–9 septa, mostly 3–7-septate, without equal-sized cells A. shizishana

2. Conidia other type 3

3. Conidia obovoid, obconical, broad turbinate or subglobose, ratio of length to width less than 2 4

3. Conidia fusiform, ratio of length to width more than 2 8

4. Conidia broadly turbinate to napiform, with 1–2 septa, distal cell largest A. janus

4. Central or distal cell of conidia largest 5

5. Conidia with 0–2 septa, or 0–3-septate 6

5. Conidia with 1–3 septa, or 2–3-septate 7

6. Conidia ellipsoid to obovoid to broadly turbinate, with 0–2 septa, 17.5–30 (23.2) × 12.5–20 (14.8) A. indica

6. Conidia globose to obovoid, with 0–3 septa, 20–44 (32) × 17–25 (20.4) μm A. sphaeroides

7. Conidia globose to turbinate, with 2–3 septa, 7–47.5 (32.2) × 17.5–27.5 (22) μm A. rutgeriense

7. Conidia subglobose, with 1–3 septa, 23.5–30 (27.6) × 17–25 (20) μm A. sinensis

8. Conidia with 4–12 septa, conidia longer A. multiformis

8. Conidia with 2–5 septa 9

9. Conidial less than 20 μm wide 10

9. Conidial wider than 20 μm 11

10. Conidia fusiform to ellipsoid, with 2–3 septa, 32.5–47.5 (41) × 12.5–17.5 (15.5) μm A. fusiformis

10. Conidia fusiform to ellipsoid, with 0–4 septa, mostly 3-septate A. salina

11. Conidia mostly 4-septate 12

11. Conidia mostly with 2 or 3–4 septa 13

12. Conidia broadly fusiform, with 2–4 septa, mostly 4-septate, with larger size A. mega lospora

12. Conidia fusiform, sometimes with 5 septa, 50–65 × 20–25 μm A. reticulata

13. Conidia turbinate, obovoid, fusiform, mostly 2–3-septate, with narrower and longer basal cell A. cookedickinson

13. Conidia fusiform to obpyriform 14

14. Conidia 2–5-septate, mostly 3–4-septate, 40–90 (54) × 15–27.5 (18) μm A. longiphora

14. Conidia mostly 2–3-septate 15

15. Conidia mostly 3-septate, 40–52–65 × 17–20–23 μm A. oudemansii

15. Conidia 1–4-septate, mostly-2 septate, obpyriform to fusiform A. huaxiensis

16. Conidiophores often merged into a bundle A. dendroides

16. Conidiophores not merged into bundles 17

17. Conidia 0–1-septate 18

17. Conidia 1- or more than 1-septate 23

18. Conidia lacking septa 19

18. Conidia 0–1-septate 20

19. Conidia obovoid to ellipsoid, 15–31 (23.6) × 10–20 (15.9) μm A. amerospora

19. Conidia elongate-ellipsoid, 11–16.8 × 5–6.6 μm A. nonseptata

20. Conidia produced from longer sterigmata, conidia occasionally 1-septate, 17.5–32.5 (22.57) × 2.75–7.5 (5.5) μm A. yunnanensis

20. Conidia producing from swollen denticles of apex 21

21. Conidia broadly ovoid to ellipsoid, 14.8–21.5 × 10.1–16.3 μm A. latispora

21. Conidia other type 22

22. Conidia ellipsoid, occasionally 1-septate, 12–28 × 10–15 µm A. botryospora

22. Conidia cylindrical to clavate 23

23.Conidiophores with apical as well as intercalary clusters of conidia, conidia cylindrical, occasionally clavate, minority 1-septate at centre A. anomala

23. Conidiophores with apical clusters of conidia only, conidia clavate, septum near the base A. pseudoclavata

24. Conidia always 1-septate 25

24. Conidia sometimes more than 1-septate 39

25. Conidiophores with longer sterigmata at the apex, of the candelabrelloid type 26

25.Conidiogenous loci denticles, or shorter sterigmata 27

26. Conidia obovoid to clavate, narrowed at septum A. javanica

26. Conidia elongate-obovoid or ovoid, not narrowed at septum, with narrower and slender basal cell, 33.5–57 × 11–15.5 μm A. shahriari

27. Conidiophores geniculation because of repeated elongation, each conidiogenous loci with 1–3 conidia 28

27. Conidiophores erect, not geniculation 30

28.Conidiogenous loci without obvious denticles, conidia narrow pyriform, 24–40 × 12.5–18.8 μm A. paucispora

28. Conidiogenous loci with obvious denticles 29

29. Conidia broadly pyriform, 25–35 × 18–24 μm, capturing nematodes by adhesive networks A. cystosporia

29. Conidia obpyriform, 24–32.5 × 12.5–20 μm, capturing nematodes by simple hyphae A. perpasta

30. Conidiogenous loci without obvious denticles, capturing nematodes by simple hyphae A. flagrans

30. Conidiogenous loci with typical denticles or sterigmata 31

31. Conidiophores with several groups denticles 32

31. Conidiophores with apical or occasionally subapical denticles or sterigmata 34

32. Conidia subellipsoid, not narrowed at septum, 7.5–27.5 (5.8) × 5–10.5 (6.6) μm A. superba

32. Conidia obovoid to pyriform 33

33. Conidia obovoid, not narrowed at septum, 28.5–32 (30) × 18–20.5 (20) μm A. obovata

33. Conidia pyriform to obovoid, narrowed at septum, 17–35 (23) × 8.5–16 (12.1) μm A. oligospora

34. Conidiophores unbranched 35

34. Conidiophores branched or occasionally branched 36

35. Conidia obconical, produced from denticles, 15–37.5 (8.4) × 7.5–14.5 (11.8) μm A. conoides

35. Conidia ellipsoid, produced from sterigmata, 20–47.5 (30.9) × 7–12.5 (10.3) A. musiformis

36. More than 10 conidia arranged in a close capitate head 37

36. 1–6 conidia arranged in a loose capitate head 38

37. Conidia pyriform, occasionally ovoid, 26–40 × 12–23 µm A. apscheronika

37. Conidia ellipsoid to ovoid, 10–20 (17.5) × 5–8 (6.2) µm A. cladodes

38. Conidia elongate-ovoid, produced from denticles, 22.5–32 × 11–22.5 µm A. chazarica

38. Conidia obovoid, produced from sterigmata, 20–27.5 (24.4) × 7.5–12.5 (10.8) µm A. robusta

39. Conidia with more septa, mostly 2–5-septate, capturing nematodes by simple two-dimensional networks A. dianchiensis

39. Conidia less than 4-septate, capturing nematodes by three dimensional networks

40. Conidia sometimes non-septate 41

40. Conidia at least 1-septate 42

41. Conidia multiform, broadly turbinate to narrow fusiform, ellipsoid, clavate, obovoid A. mangrovispora

41. Conidia fusiform, largest cell obvious A. micro scaphoides

42. Conidia fusiform or other type 43

42. Conidia other type, never fusiform 48

43. Conidia fusiform to other type 44

43. Conidia only fusiform 45

44. Conidia fusiform, obovoid or broadly conical, 3-septate, 37–55 (49) × 17.5–35 (28)

μm A. eudermata

44.Conidia pyriform or fusiform, 1–3-septate, mostly 1-septate A. guizhouensis

45. Conidia mostly 3-septate 46

45. Conidia mostly 4 or 3–4-septate 47

46. Conidia of two types, macroconidia arranged loosely, 3–4-septate, 30–50 (45.1) × 8–16.5 (12.2) μm A. polycephala

46. Conidia arranged closely, 1–4-septate, 30–60 (36.2) × 15–30 (20.2) μm A. thaumasia

47. Conidia sometimes curved, mostly 4-septate, 40–70 × 9–14 μm A. gampsospora

47. Conidia mostly 3–4-septate, 46–70 (62.3) × 21–29 (24.7) A. psychrophila

48. Sterigmata or denticles formed from flank of conidiophores 49

48. Conidiophores with apical and at least subapical clusters of conidia 50

49. Conidia pyriform to broadly clavate,1–3 septa, mostly 2-septate, 25–40 (17.5) × 7.5–19 μm A. clavispora

49. Conidia elongate-ovoid to ellipsoid, 1–3-septate, mostly 1–2 septa, 28.5–56 × 11.5–22.5 μm A. tabrizica

50. Conidia mostly 1-septate or with 1–2 septa 51

50. Conidia mostly 2-septate or with 2–3 septa 52

51. Conidia obovoid to ellipsoid, mostly 1–2-septate, 18–36 (28.1) × 12–20 (15.3) µm A. azerbaijanica

51. Conidia pyriform, 1–2-septate, mostly with 1 septum A. oviformis

52. Conidia broadly pyriform to subcylindrical, mostly 2–3-septate, occasionally 1-septate, 20–35 × 10–25 μm A. pyriformis

52. Conidia ellipsoid, obovoid or cymbiform 52

53. Conidia of two types, macroconidia ellipsoid or cymbiform,1–3-septate, mostly 2-septate A. scaphoides

53. Conidia ellipsoid to obovoid or cymbiform, 2–3-septate A. vermicola

Accepted Species of Arthrobotrys

1. Arthrobotrys amerospora S. Schenck, W.B. Kendr. & Pramer, Can. J. Bot. 55 (8): 979 (1977) [1976]

Characteristics:

Mycelium hyaline, septate, branched. Conidiophores simple, erect, septate, unbranched, 75–250 µm long, producing 2–10 conidia singly from retrogressive conidiogenous loci on broad, conspicuous denticles at and near the apex. Conidia holoblastic, hyaline, obovoid, one-celled, 15–31 (23.6) × 10–20 (15.9) µm with a small truncate protuberance at the base. Germinating from the base, and often subsequently also from the apex. Chlamydospores yellowish, smooth-walled, sphaerical to elongate-ellipsoidal, 18–50 × 18–23 µm, usually intercalary, single or in chains. Capturing nematodes on adhesive hyphal loops.

Distribution:

Canada, China (Guansi), India, USA.

Notes:

The description is based on the protologue. Among Arthrobotrys, there are five species with single celled conidia, i.e. A. amerospora (Schenck et al. 1977), A. anomala (Barron and Davidson 1972), A. botryospora (Barron 1979), A. yunnanensis (Mo et al. 2005a) and A. nonseptata (Yu et al. 2009b). However, only conidia of A. amerospora and A. nonseptata are consistently non-septate, and conidia of the other three species are occasionally 1-septate. The obovoid conidia of A. amerospora distinguishes it from the elongate-ellipsoidal conidia of A. nonseptata. (Fig. 3.1)

Characteristics:

Conidiophores short, erect or suberect, hyaline, indeterminate, 20–80 × 4–6 µm; conidia borne in an apical cluster or series of clusters, sometimes borne irregularly along the spore-bearing apex; conidia cylindric to long ellipsoid, occasionally clavate, hyaline, non-septate when attached, frequently forming a septum before germination, produced sympodially on pronounced denticles, 13–22 × 3–7 µm. Nematodes trapped by means of short, erect adhesive branches or more commonly by complex three dimensional adhesive networks.

Distribution:

Canada.

Notes:

The description is based on the protologue. Arthrobotrys anomala is characterized by cylindric to elongate ellipsoidal, 0 (–1)-septate conidia, which distinguish it from other species of Arthrobotrys. (Fig. 3.2)

Arthrobotrys anomala G.L. Barron & J.G.N. Davidson, Can. J. Bot. 50: 1773 (1972)

Arthrobotrys apscheronica Mekht., Nov. Sist. Niz. Rast., 10: 174 (1973)

Characteristics:

Conidiophores erect or curved, sometimes branched, occasionally repeated propagated, conidiophore apex expanded irregularly, bearing 12 (–16) conidia on denticles of apex; conidia pyriform, seldom ovoid, 1-septate at the centre of conidia, constricted at the septum. Nematodes trapped by three dimensional adhesive networks.

Distribution:

Russia.

Notes:

The description is based on the protologue. This species is similar to A. conoides in conidial shape, but it differs in having longer conidia (Fig. 3.3).

Arthrobotrys azerbaijanica (Mekht.) Oorschot [as ‘azerbaidzhanica’], Stud. Mycol. 26: 70 (1985)
Nematophagus azerbaijanicus Mekht. [as ‘azerbaidzhanicus’], Mikol. Fitopatol. 9: 250 (1975)

Characteristics:

Conidiophores erect, branched or unbranched, repeatedly propagating at least once, apex expanded, bearing 10–12 conidia on short and slender denticles; conidia obovoid to ellipsoidal, 1–4-septate, constricted at septum, sometimes 1–2 cells expanded, 18–36 (28.1) × 12–20 (15.3) µm; Chlamydospores present. Nematodes trapped by three dimensional adhesive networks.

Distribution:

Russia.

Notes:

The description is based on the protologue. This species resembles A. pyriformis, but has wider conidia (conidia of A. pyriformis 17–38 × 6.5–11.5 μm, mostly 2–3-septate). (Fig. 3.4)

Arthrobotrys botryospora G. L. Barron, Can. J. Bot. 57: 1371 (1979)

Characteristics:

Colonies on CMA whitish. Mycelium spreading, vegetative hyphae hyaline, septate branched. Conidiophores hyaline, erect, septate, 250–350 µm long, 4.5–6.5 µm wide at the base, gradually tapering upwards to a width of 3–5 µm at the apex, simple or sparingly branched in strikingly loose capitate arrangement. Conidia 12–28 × 10–15 µm, hyaline, ellipsoid, non-septate or occasionally 1-septate (8 %) just below the centre of the spore and having a narrowly truncate protuberance at the base. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Canada (Ontario), China (Anhui, Beijing, Guizhou, Hebei)

Material examined:

C9–1, C21–1, isolated from forest soil in Cangshan Mountain, Dali in 1999 by Lu Cao; 01–3, isolated from forest soil in Shigu, Lijiang in 1999 by Lu Cao.

Notes:

The only species of Arthrobotrys described with non-septate conidia are A. anomala and A. amerospora. Arthrobotrys anomala differs from A. botryospora in its cylindrical conidia. In A. amerospora, the conidia are larger than those of A. botryospora. The former also produce abundant chlamydospores, while chlamydospores are not produced in A. botryospora. In A. amersospora the conidia form in a solitary terminal cluster, produced from a retrogressive conidiogenous locus which remains relatively unswollen. In A. botryospora, successive production of conidia produces a swollen apex, with the main axis branching or elongating sympodially to produce a succession of spore clusters. (Fig. 3.5)

Arthrobotrys chazarica Mekht., Mycol. Res. 102: 683 (1998)

Characteristics:

The fungus forms a delicate, fluffy, pale grey colony in pure culture on malt agar with pigments diffusing into the agar. Sporulation is abundant. Conidiophores simple, erect, branched. Conidia obovate to elongate-obovate, 1-septate, 22.5–32 × 11–22.5 μm, growing on very closely arranged, thin denticles. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Azerbaijan (Baku).

Notes:

The description is based on the protologue. This species is similar to A. robusta in being 1-septate at the centre of the conidia, but conidia of A. robusta are mainly oblong-pyriform, and conidia are smaller. (Fig. 3.6)

Arthrobotrys cladodes Drechsler, Mycologia 29: 463 (1937)
Trichothecium cladodes (Drechsler) Soprunov, Predacious fungi—Hyphomycetes and their use in the control of pathogenic nematodes: 113 (1958)

Characteristics:

Colonies on CMA whitish, slow growing. Mycelium spreading, scanty; vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, erect, septate, more or less branched, 68–236 μm long, 2.5–5 μm wide at the base, tapering gradually upwards to a width of 2–3 μm below the irregularly expanded, globose or somewhat coralloid apex, whereon are borne 10–20 conidia usually in a dense capitate arrangement. Conidia hyaline, ellipsoid or elongate obovoid, mostly 10–20 (17.5) × 5–8 (6.2) μm, 1-septate near the centre of the spore. Chlamydospores not formed. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Beijing, Guizhou, Hebei, Taiwan, Xizang, Yunnan), Cuba (Prov. Ciudad de La Habana), UK, USA (Wisconsin)

Material examined:

YMF1.00038, isolated from forest soil in Deqin, Yunnan, in 2002 by Jing Zhang; ①–33, isolated from field soil in Guiyang, Guizhou, in May 2002 by Ke-Qin Zhang; XZA–3, isolated from field soil in Zhouxian, Xizang in August 2002, by Minghe Mo. Permanent slide: H1–33.

Notes:

This species was first isolated from leaf mold of deciduous woods in Virginia and Maryland, which is similar to A. superba, A. oligospora and A. conoides in conidia shape, but branch mode of conidiophores differ. The apex of the A. cladodes conidiophore is irregularly expanded, on which 10–20 conidia form in a densely capitate arrangement. (Fig. 3.7)

Arthrobotrys clavispora (R.C. Cooke) S. Schenck, W.B. Kendr. & Pramer, Can. J. Bot. 55: 982 (1977)
Dactylaria clavispora R.C. Cooke, Trans. Br. Mycol. Soc. 47: 307 (1964)
Genicularia clavispora (R.C. Cooke) Rifai, Reinwardtia 7 (4): 367 (1968)
Geniculifera clavispora (R.C. Cooke) Rifai, Mycotaxon 2 (2): 216 (1975)
Nematophagus clavisporus (R.C. Cooke) Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 107 (1979)

Characteristics:

Conidiophores erect, unbranched, septate, 150–350 μm high, at the apex of each bearing 3–11 widely spaced conidia, pleurogenous on small sterigmatal branches. A single, terminal conidium is formed at the conidiophore apex, which continues to grow for a short distance so that the conidium is displaced laterally. A second conidium is then formed at the new apex followed by growth of the conidiophore displacing this conidium. This process is repeated giving rise to the arrangement of conidia typical of this species. Conidia pyriform to broadly clavate, 25–40 (17.5) × 7.5–19 μm, rounded distally and tapering proximally to a narrow, truncate base. They are 1–2-septate, about twice as many having one septum as two. In both forms of conidium the distal cell is usually the larger. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

France.

Notes:

The description based on the protologue. This species is characterized by widely spaced conidia borne pleurogenous on small sterigmatal branches. (Fig. 3.8)

Arthrobotrys conoides Drechsler, Mycologia 29 (4): 476 (1937)
Arthrobotrys pravicovii (Soprunov) Sidorova, Gorlenko & Nalepina [as ‘pravicovi’], Bot. Zh. SSSR 49: 1598 (1964)
Arthrobotrys pravicovii (Soprunov) Mekht. [as ‘pravicovi’], Dokl. Akad. Nauk Azerb. SSR 20 (6): 71 (1964)
Arthrobotrys tortor Jarow., Acta Mycologica, Warszawa 4: 241 (1968)
Trichothecium pravicovii Soprunov [as ‘Pravicovi’], Predacious fungi—Hyphomycetes and their use in the control of pathogenic nematodes: 117 (1958)

Characteristics:

Colonies on CMA whitish then turned to yellowish; mycelium spreading, vegetative hyphae hyaline, septate, branched, except for occasional storage filaments that are densely filled with protoplasm and up to 12 μm wide, measuring mostly 2–8 μm in diameter. Conidiophores hyaline, erect, 5–10-septate, usually not branched, mostly 4–7.5 μm wide at the base, tapering gradually upwards to a width of 2.5–5 μm in attaining a height of 120–420 μm before bearing on a globose or more irregularly expanded apex as many as 30 conidia in dense capitate arrangement; subsequently often, following repeated elongation, giving rise successively to additional clusters of conidia. Conidia hyaline, obconical, 15–37.5 (28.4) × 7.5–14.5 (11.8) μm, somewhat flattened at the base, broadly rounded at the apex, 1-septate, usually perceptibly constricted at the at the septum. Chlamydospores yellowish, globose or prolate ellipsoidal, 17–24 μm in diameter, or sometimes narrower, oblong-cylindrical, 30–50 μm long and approximately 15 μm wide. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Hainan, Hubei, Tianjing, Xizang, Yunnan), France, Germany (Berlin), Netherlands, Russian, South Africa (North West Province), Spain (Chavio verde), USA.

Material examined:

8705, isolated from dunghill in Huaxi, Guizhou in 1988 by Ke-Qin Zhang; GZHS–3, isolated from forest soil in Huishui, Guizhou in 1996 by Ke-Qin Zhang; J9–1, J11–2, J5–3, isolated from soil in Jianshui, Yunnan in 1999 by Yanju Bi; TJ–W1Z03, isolated from soil in Wanglanzhuang, Tianjing in 2000 by Wenpeng Li; XZA–4, isolated from pasture soil in Xizang in August 2000 by Minghe Mo; DL1–1, isolated from forest soil in Dali, Yunnan in September 2002 by Jing Zhang; YMF1.00009, YMF1.00541, YMF1.00866, J49–1, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; YMF1.00009, YMF1.00541, isolated from forest soil in Baoshan, Yunnan in June 2002 by Jing Zhang; YMF1.00551, YMF1.00866, isolated from forest soil in Lijiang, Yunnan in October 2002 by Jing Zhang. Permanent slide: J49–1.

Notes:

A. conoides has an extensive worldwide distribution, and was first isolated from delaying leaves from a greenhouse (Drechsler 1937). It resembles A. oligospora and A. superba in most morphological characters, with the exception of conidial shape and the position of septum. In A. conoides, conidia are elongate obconical, 1-septate in the lower third and constricted at the septum. In A. oligospora, conidia are obovoid, 1-septate near the base of the spore, and constricted at the septum. In A. superba, conidia are ellipsoidal, and 1-septate at the centre of the conidia.

The characters of examined strains match well with the original description (Drechsler 1937). Van Oorschot (1985) rechecked A. tortor deposited in CBS and ATCC, and found that A. tortor cannot be distinguished from A. conoides, and treated A. tortor as the synonym of A. conoides. (Fig. 3.9)

Arthrobotrys cystosporia (Dudd.) Sidorova, Gorlenko & Nalepina, Bot. Zh. SSR 49: 1598 (1964)
Trichothecium cystosporium Dudd. Trans. Br. Mycol. Soc. 34: 600 (1952)
Arthrobotrys cystosporia (Dudd) Mekht.[as ‘cystosporium’], Dokl. Akad, Nauk Azerb. SSR 20 (6): 70 (1964)
Genicularia cystosporia (Dudd.) Rifai, Mycotaxon 2 (2): 215 (1975)

Characteristics:

The mycelium consist of straight, septate hyphae, 3–6 μm wide, sparingly branched. Conidiophores hyaline, erect or geniculate due to repeated propagated, usually not branched, attaining a height of 100–400 μm. The loose group of spores having the appearance of a panicle thus formed at each conidiogenous loci. The conidia hyaline, broadly pyriform, 25–35 × 18–24 μm, 1-septate near the base, proximal cell much larger. No chlamydospores were observed. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Japan, UK.

Notes:

The description based on the protologue. Conidia of this species are arranged loosely, not grown from typical denticles, but from sterigmata. (Fig. 3.10)

Arthrobotrys cookedickinson (Cooke & Dickinson) Z.F. Yu, comb. nov.
Monacrosporium cystosporum Cooke & Dickinson, Trans. Br. Mycol. Soc. 48: 623 (1965)
MB 804791

Characteristics:

Vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, erect, simple, 8–11-septate, 60–420 μm long, 5–7.5 μm wide at the base, gradually tapering upwards to a width of 3–5 μm at the apex, bearing a single conidium. Conidia hyaline, broadly clavate or broadly turbinate to obovoid, 30–52.5 (42) × 15–22.5 (17.6) μm, 1–3-septate, mostly 2–3-septate with an almost globose terminal cell, distally rounded and tapered to a long tail formed by the two basal cells, the proximal one being narrowly truncate. Chlamydospores present. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Guizhou, Sichuan, Xizang, Yunnan), Germany (former FRG)

Material examined:

②–1–1, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; XZM–2, isolated from soil in Xizang in August 2000 by Minghe Mo; DH4–2, isolated from soil in Ruili, Yunnan in October 2002 by Jing Zhang; YMF1.00024, isolated from forest soil in Jiuzhaigou, Sichuan in 2003 by Xuefeng Liu. Permanent slide: ②–1–1

Notes:

This species is transferred to Arthrobotrys from Monacrosporium and renamed as A. cookedickinson to avoid confusing with A. cystosporia (Dudd.) Mekht. (1964). Cooke & Dickinson indicated A. cookedickinson was closely related to A. eudermata, but conidia of the latter were described as being much larger. Based on our observation, A. cookedickinson resembles A. sphaeroides in conidial shape, but A. cookedickinson is characterised by tail-like basal cell, which is absent in A. sphaeroides. (Fig. 3.11)

Arthrobotrys dendroides Kuthub. Muid & J. Webster Trans. Br. mycol. Soc. 84 (3): 564 (1985)

Characteristics:

Colonies on CMA whitish, effuse, with scattered erect hyaline synnemata. Mycelium superficial, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores simple, septate, erect, solitary or synnematous; mainly synnematous on natural substrata, synnemata 0.5–1.2 mm wide, 1 cm tall; conidiophores sometimes elongating sympodially to form additional heads of conidia at higher levels; when synnematous individual threads slender, septate, smooth, straight except near the apex, splaying out to become flexuous near apex, individual conidiophores up to 800 μm long and 2–3 μm wide. Conidiogenous cells polyblastic, integrated, terminal, raduliform. Conidia 10–20 (14.6) × 2.5–5 (4) μm, hyaline, ovate to oblong, 1-septate. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Yunnan), Malaysia (Kuala Lumpur), USA

Material examined:

YMF1.00010, isolated from forest soil in Shuangbai, Yunnan in February 2001 by Xuefeng Liu. Permanent slide: Sb02–4.

Notes:

A. dendroides is different from other species of Arthrobotrys because synnematous conidiophores even in cultures. (Fig. 3.12)

Arthrobotrys dianchiensis (Y. Hao & K.Q. Zhang) Z. F. Yu, comb. nov.
Dactylella dianchiensis Y. Hao & K.Q. Zhang, Mycotaxon 82: 236 (2004)
MB 804792

Characteristics:

Colony on PDA initially whitish and turning orange white after 10 days of incubation, rapidly growing and extending 7 cm in diameter at 28 °C, 5 cm at 25 °C within 4 days. At the same time the reverse side of the media becomes faintly yellow to reddish orange. Colonies on CMA whitish, rapidly growing and extending to a diameter of 6 cm at 25 °C within 6 days. Mycelium hyaline, scanty, hyphae septate, branched, 2.5–5 μm wide. Conidiophores erect, simple or branched, 2–4-septate, 245–425 μm long, 5–7.5 μm wide at the base, gradually tapering upwards to a width of 2.5–5 μm at the apex, initially a width of 2.5–5 μm at the apex, later often producing a few short branches or spurs near the apex, and bearing 2–3 conidia in sympodial arrangement. Conidia hyaline, spindle-shaped or clavate, narrowly round at the distal end, truncate at the base, 37.5–100 (70) × 10–17.5 (14.3) μm, 1–7-septate, mainly 2–5-septate. The proportion of conidia with 1, 2, 3, 4, 5, 6 and 7 septa is 10, 17, 14, 24, 22, 9 and 4 %, respectively. Some conidia had small tubercles at the both ends and could germinate from these tubercles. Conidia could produce secondary conidiophores and secondary conidia. The secondary conidia are spindle-shaped, 23.9 × 5 μm and 1-septate. Capturing nematodes by means of adhesive two dimensional networks.

Distribution:

China (Yunnan)

Material examined:

YMF1.00471, isolated from fresh water soil in Dianchi, Yunnan in 2002 by Yu’e Hao.

Notes:

The description is based on the protologue. A. dianchiensis is similar to A. multiformis in primary conidial shape, but it can be distinguished from A. multiformis by the size and septation of primary conidia. (Fig. 3.13)

Arthrobotrys eudermata (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 102 (1999)
Dactylella eudermata Drechsler, Mycologia 42 (1): 40 (1950)
Dactylella eudermata (Drechsler) Seifert & W.B. Kendr., in Seifert, Kendrick & Murase, Univ. Waterloo Biol. Ser. 27: 30 (1983)
Genicularia eudermata (Drechsler) Rifai, Reintiwarda 7 (4): 367 (1968)
Geniculifera eudermata (Drechsler) Rifai, Mycotaxon 2 (2): 216 (1975)
Golovinia eudermata (Drechsler) Mekht., Dokl. Akad. Nauk Azerb. SSR 27 (2): 73 (1971)
Monacrosporium eudermatum (Drechsler) Subram., J. Indian bot. Soc. 42: 293 (1964) [1963]

Characteristics:

Colonies on CMA whitish, rapidly growing. Mycelium spreading, vegetative hyphae hyaline, septate, branched, 1.8–7.5 μm wide. Conidiophores hyaline, 2–8-septate, erect, simple, 400–680 μm long, 5–8 μm wide at the base, gradually tapering upwards to a width of 2–3 μm at the apex, bearing a single conidium or 2–4 additional conidia. Conidia globose to broadly turbinate or broadly spindle-shaped, rounded at the distal end and truncate at the base, the central cell the largest, 37–55 (49) × 17.5–35 (28) μm, 1–3-septate; microconidia ellipsoid, aseptate, rounded at the distal end and truncate at the base, 10–15 × 5–6 μm. Chlamydospores present on aged cultures, globose, forming in chain or clusters, smooth-walled, yellow. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Beijing, Fujian, Guangxi, Hebei, Huibei, Huinan, Shangdong, Xizang, Yunnan, Zhejiang), Burkina Faso, Germany (Berlin-Dahlem), Spain (La Palma, Tenerife)

Material examined:

J42–1, J38–2, isolated from soil in Jianshui, Yunnan in 1999 by Yanju Bi; XZM–4, isolated from forest soil in Xizang in August 2000 by Minghe M; YMF1.00120, YMF1.00542, YMF1.00545, isolated from soil in Lijiang, Yunnan in September 2002 by Jing Zhang. Permanent slide: LJ3–4.

Notes:

A. eudermata resembles A. psychrophila and A. thaumasia in conidial shape, but differs in conidiophores and width of conidia, respectively. Conidia of A. eudermata are considerably wider than in A. thaumasia. Moreover, in A. eudermata, conidiophores are simple, bearing a single conidium at the apex, or 2–4 additional conidia, while in A. thaumasia, conidiophores are usually branched near the apex, bearing 3–15, sometimes up to 25 conidia on blunt sterigmata in loose capitate arrangement. The difference between A. eudermata and A. psychrophila is that conidia of A. psychrophila are longer than in A. eudermata. (Fig. 3.14)

Arthrobotrys flagrans (Dudd.) Sidorova, Gorlenko & Nalepina, Bot. Zh. SSSR: 1598 (1964)
Trichothecium flagrans Dudd. Trans. Br. mycol. Soc. 32 (3–4): 287 (1950)
Arthrobotrys flagrans (Dudd.) Mekht., Dokl. Akad. Nauk Azerb. SSR 20 (6): 70 (1964)
Duddingtonia flagrans (Dudd.) R.C. Cooke, Trans. Br. Mycol. Soc. 53 (2): 316 (1969)

Characteristics:

Colonies effused, scanty, with few aerial hyphae. Conidiophores erect, straight, unbranched, attaining 150 μm long, bearing 2–6 conidia at the apex. Conidia obconical to ellipsoidal, 1-septate, the proximal cell broadly truncate, 25–50 × 10–15 μm. Intercalary chlamydospores present abundantly. Capturing nematodes by means of adhesive three dimensional hyphae.

Distribution:

Germany, Soviet, UK.

Notes:

The description is based on the protologue. This species has not typical denticles or sterigmata which exist among other species of Arthrobotrys, but it has typical adhesive three dimensional hyphae. (Fig. 3.15)

Arthrobotrys fusiformis (R.C. Cooke & C.H. Dickinson) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 102 (1999)
Monacrosporium fusiforme R.C. Cooke & C.H. Dickinson [as ‘fusiformis’], Trans. Br. mycol. Soc. 46: 628 (1965)
Golovinia fusiformis (R.C. Cooke & C.H. Dickinson) Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 160 (1979)

Characteristics:

Vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, erect, single, 3–7-septate, 250–390 μm long, 5 μm wide at the base, gradually tapering upwards to a width of 2.5–3 μm at the apex, bearing a single conidium, sometimes a second conidium formed on an about 15 μm branch near the conidiophore apex. Conidia hyaline, fusiform-ellipsoidal, 32.5–47.5 (41) × 12.5–17.5 (15.5) μm, 2–3-septate, rounded at the distal end and truncate at the base. Chlamydospores not observed. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Hebei, Guizhou, Tianjing, Yunnan, Zhejiang), USA

Material examined:

YMF1.00034, isolated from field soil in Balitai, Tianjingin 2001 by Wenpeng Li. Permanent slide: LT–11–03–3

Notes:

According to Cooke & Dickinson (1965), A. fusiformis is similar to A. psychrophila and A. salina, but the dimensions, the shape and the septation of conidia distinguish it from these species. (Fig. 3.16)

Arthrobotrys gampsospora (Drechsler) S. Schenck, W.B. Kendr. & Pramer, Can. J. Bot. 55 (8): 982 (1977)
Dactylaria gampsospora (Drechsler) de Hoog & Oorschot, Stud. Mycol.26: 110 (1985)
Dactylaria gampsospora Drechsler, Sydowia 15 (1–6): 9 (1962)
Monacrosporium gampsosporum (Drechsler) Xing Z. Liu & K.Q. Zhang, Mycol. Res. 98 (8): 865 (1994)
Woroninula gampsospora (Drechsler) Mekht., Khishchnye Nematofagovye Griby- Gifomitsety (Baku): 112 (1979)

Characteristics:

Mycelium colourless, branched, septate. Conidiophores erect, mostly 150–626 μm high, 5–7 μm wide at the base, tapering to 2–3 μm at the apex, bearing several conidia in a loose head on tooth–like projecting often 3–5 μm long. Conidia hyaline, spindle-shaped, curved, 1–4-septate, mostly 4-septate, 25–76 × 7–16 μm. Microconidiophores often 1–3-septate, 75–125 μm high, 4–5 μm wide at the base, tapering to a width of 1.2–2 μm long at the apex, furnished distally with several tooth-like projections 1.5–2 μm long on which bearing microconidia. Microconidia colourless, elongate obovoid, tapering towards the base, broadly rounded at the distal end, 10–17 × 4–6 μm. Chlamydospores present, 8–21 × 6–17 μm Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Canada, USA.

Notes:

The description is based on the protologue. This species is different from other species of Arthrobotrys in its curved and more septate conidia. (Fig. 3.17)

Arthrobotrys guizhouensis K.Q. Zhang, Acta Mycol. Sin. 13: 101 (1994)

Characteristics:

Colonies on CMA initially whitish and turned to reddish, rapidly growing. Mycelium spreading, dense, vegetative hyphae hyaline, septate, branched, mostly 3–9 μm wide. Conidiophores hyaline, erect, branched, 5–10-septate, 120–370 μm long, 5–7.5 μm wide at the base, tapering upwards to a width of 4–5 μm before bearing on irregularly expanded apex whereon form conidia; subsequently often, following repeated elongation, giving rise successively to additional clusters of conidia. Two type of conidia appear, macroconidia fusoid to ellipsoidal, 34–42.5 × 14–17.5 μm, 1–3-septate, proportion of conidia with 1, 2, and 3 is 95, 4 and 1 %, respectively. Microconidia pyriform, 1-septate, 19–30 × 8.4–14 μm. Chlamydospores yellowish, globose, 7.5–12.5 μm in diameter. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Yunnan).

Material examined:

8736, isolated from soil in Guiyang, Guizhou in September 1987 by Ke-Qin Zhang; GZFJ-48, isolated from forest soil in Fanjing Mountain, Guizhou in 1996 by Ke-Qin Zhang;YMF1.00014, isolated from field soil in Wenshan, Yunnan in April 2002 by Zhiwei Zhao; LJ1–9-2, isolated from soil in Lijiang, Yunnan in September by Jun Zhang. Permanent slide: P4. 50–1.

Notes:

A. guizhouensis morphologically resembles A. oviformis and A. vermicola. However, A. guizhouensis differs from A. oviformis in irregularly expanded conidiophores at the apex, and larger conidia. It also differs from A. vermicola in branched and irregularly expanded conidiophores at the apex, and mostly 1-septate conidia. In A. vermicola, conidiophores are unbranched and not expanded at the apex, conidia are mostly 2–3-septate. (Fig. 3.18)

Arthrobotrys huaxiensis (K.Q. Zhang, Xing Z. Liu & L. Cao) Z.F. Yu, comb. nov.
Monacrosporium guizhouense K.Q. Zhang, Xing Z. Liu & L. Cao, Mycol. Res. 100: 275, 1996
MB 804790

Characteristics:

Colonies on CMA pink. Hyphae hyaline, thin-walled, septate, frequently branched, 1.5–5 μm wide. Conidiophores hyaline, septate, single, simple, erect, 172–350 μm long, 3.5–6 μm wide at the base, gradually tapering upwards to a width of 2–2.5 μm at the apex, bearing a single conidium. Conidia hyaline, obpyriform to fusiform, 1–4-septate, mostly 2-septate, 30.5–71.5 (52.7) × 18.5–28.5 (23.9) μm. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou)

Material examined:

GAU1001, isolated from soil in Huaxi, Guizhou in October 1993 by Ke-Qin Zhang.

Notes:

This species traps nematodes by means of three dimensional adhesive networks, which was transferred from Monacrosporium to Arthrobotrys based on the present classification and renamed as A. huaxiensis Z.F. Yu to avoid confusing with A. guizhouensis K.Q. Zhang (1994). A. huaxiensis resembles A. cookedickinson and A. fusiformis in conidial septation, but differs in its fusiform to obpyriform conidia, conidial size and also in its unbranched conidiophores. (Fig. 3.19)

Arthrobotrys indica (Chowdhry & Bahl) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 102 (1999)
Monacrosporialla indica Chowdhry & Bahl [as ‘indicum’], Curr. Science 51: 895 (1982)

Characteristic:

Vegetative hyphae hyaline, septate, branched, 2–3 μm wide. Conidiophores hyaline, erect, simple or occasionally branched, 8–20-septate, 150–350 μm long, 3–6 μm wide at the base, gradually tapering upwards to a width of 1–2 μm at the apex. Conidia hyaline, elliptic or broadly top–shaped, 0–2-septate, rounded at the distal end and truncate at the base, a navel at the base, 17.5–30 (23.2) × 12.5–20 (14.8) μm. Chlamydospores present. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Xizang), India (Delhi)

Material examined:

Sjz3.11.1, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; XZM–7, isolated from soil in Xizang in August 2000 by Minghe Mo.

Notes:

A. indica resembles A. eudermata and A. cookedickinson in conidial shape, but the dimension of conidia in A. eudermata is larger than in A. indica. A. indica produces navels at the base of conidia while this character is absent in A. cookedickinson. (Fig. 3.20)

Arthrobotrys janus (S.D. Li & Xing Z. Liu) Z.F. Yu, comb. nov.
Monacrosporium janus S.D. Li & X.Z. Liu, Mycol. Res. 107: 890 (2003)
MB 804791

Characteristics:

Colonies growing rapidly on PDA, attaining 8 cm diameter within 7 days at 25 °C, producing orange reddish pigment resulting in medium colored. Aerial mycelium fluffy, whitish when young and becoming light yellowish when aged. Hyphae hyaline, septate branched. Conidiophores hyaline, simple, slender, erect, 185–250 μm long, 5–6.5 μm wide at the base, tapering to 1.5–2.5 μm wide at the apex, bearing a single conidium. Conidia broadly turbinate to napiform, 1–2-septate but mostly (> 65 %) 1-septate at basal part, 15–26 (22.5) × 17.5–37.5 (28.5) μm. The distal cell are sphaerical and much bigger than others, proximal cell obconic, tapering to a short truncate base, central cell disciform if any. Chlamydospores sphaerical to ellipsoid, intercalary, 7.5–25 (15.5) × 4–11.5 (7.5) μm. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Shandong)

Material examined:

YMF1.01312, isolated from field soil in Mixian, Shandong in September 2000 by Shidong Li.

Notes:

A. janus closely resembles, but differs from, A. indica, A. sphaeroides and A. sinensis in conidial morphology. According to the original description of these species, the conidia of A. indica are 22–30 × 14–20 μm, and mostly 2-septate with distinct basal hila (Chowdhry and Bahl, 1982); those of A. sphaeroides are 28–42 × 19–29 μm, usually 2-septate with one basal and one terminal septum (46 %) or 1-septate with only one basal septum (29 %) (Castaner 1968); and those of A. sinensis are 25–30.5 × 15–18 μm with 37 % 3-septate, 42 % 2-septate, and 21 % 1-septate (Liu and Zhang 1994). While conidia of A. janus are 20–25 × 24.5–32.5 μm with 1–2 transverse septa, mostly (> 65 %) are 1-septate in the basal part. When compared morphologically, A. janus can be easily distinguished from A. sinensis by its conidial shape and septation. This fungus also similar in conidial size, shape and septation to A. cystosporia (conidia 24–35.5 × 18–25 μm), A. obovata (28.5–32 × 18–20.5 μm) and A. perpasta (24–32.5 × 12.5–20 μm), but differ in that the conidiophores of all the three latter species are geniculately branched (Duddington 1951a, Rifai and Cooke 1966, Zhang et al. 1996a). (Fig. 3.21)

Arthrobotrys javanica (Rifai & R.C. Cooke) Jarow., Acta Mycologica, Warszawa 6 (2): 373 (1970)
Candelabrella javanica Rifai & Cooke, Trans. Br. mycol. Soc. 49 (1): 162 (1966)

Characteristics:

Colonies on CMA almost hyaline; mycelium spreading, vegetative hyphae hyaline, septate, branched, smooth–walled, 3–7 μm wide. Conidiophores erect, straight, subulate, hyaline, smooth, 5–10-septate, 220–400 μm long, about 5–7.5 μm wide at the base, gradually tapering to 2.5–5 μm at the apex, enlarged slightly as ramification took place and bearing a lax, short, candelabrum-like apical branching system. Conidia arose singly as blown-out ends of the conidiophore and of the subsequently developed growing points, 20–37.5 (27.9) × 7.5–10 (8.8) μm, smooth-walled and hyaline, narrowly obovoid or clavate, 1 septum, slightly constricted at the septum, rounded distally with the obconical basal cell tapering to a truncate base. Chlamydospores yellowish, subglobose, 7.5–15 μm in diameter. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Xizang, Yunnan), France (Limousin), Indonesia (Java)

Material examined:

Dian5 (4), isolated from fresh water soil in Dianchi Lake, Yunnan in 1996 by Ke-Qin Zhang et al; YMF1.00015, YMF1.00548, isolated from field soil in Lincang, Yunnan in April 1999 by Lu Cao; MW17–2, isolated from forest soil in Xishuangbanna, Yunnan in 1999 by Yanju Bi; XZA–5, isolated from field soil in Xizang in August 2000 by Minghe Mo; DH6–2, isolated from soil in Ruili, Yunnan in October 2002 by Jing Zhang. Permanent slide: LL4–1.

Notes:

Rifai and Cooke (1966) established a new genus Candelabrella Rifai and Cooke (1966) based on long, distinctive, subcylindrical conidial pegs and the candelabrum-like branching of the conidiophore. However, this genus was not accepted by most scholars, so this species was transferred into Arthrobotrys (Jarowaja, 1970). A. javanica resembles A. musiformis in the candelabrum-like branching of the conidiophores, but differs in conidia shape. In A. javanica, conidia are 20–37.5 (27.9) × 7.5–10 (8.8) μm, narrowly obovoid or clavate, while in A. musiformis, conidia ellipsoid, mostly slightly curved, 20–47.5 (30.9) × 7–12.5 (10.3) μm. (Fig. 3.22)

Arthrobotrys latispora Hong Y. Su & X.Y. Yang, in Su, Liu, Li, Cao, Chen & Yang, Mycotaxon 117: 32 (2011)

Characteristics:

Colonies grew rapidly on CMA medium, attaining 6 cm diameter in 8 days at 25 °C. Mycelium spreading, vegetative hyphae hyaline, septate and branched, mostly 2–4 μm wide. Conidiophores colourless, erect, simple, septate frequently, 60–120 μm high, 2–5 μm wide at the base and 1.8–4 μm at the apex, producing 4–12 conidia singly from conidiogenous loci on conspiculus, partly superposed nodes at and near the apex. Conidia colourless, broadly ovoid-oval, broadly rounded at the apex, rounded truncate at the narrowed base, 1-septate or aseptate at the centre, 14.8–21.5 × 10.1–16.3 (average18.3 × 13.5) μm (living state). Approximately 41 % of the conidia were non-septate and 59 % 1-septate. Chlamydospores sphaerical to ellipsoidal. Nematodes are trapped by three dimensional adhesive networks.

Distribution:

China (Yunnan)

Material examined:

YMF1.03168, isolated from soil in Yongping, Yunnan in October 2009 by Hongyan Su.

Notes:

A. latispora is characterized by its broad, ovoid or slightly oval, partly aseptate conidia, which are borne on nodes. Based on conidial shape, A. latispora most closely resembles A. amerospora. The conidia of both species are ovoid, but differ in conidial size and septation. (Fig. 3.23)

Arthrobotrys longiphora (Xing Z. Liu & B.S. Lu) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 102 (1999)
Monacrosporium longiphorum Xing Z. Liu & B.S. Lu, Mycosystema 6: 65 (1993)

Characteristics:

Arthrobotrys microscaphoides (Xing Z. Liu & B.S. Lu) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 103 (1999)
Monacrosporium microscaphoides Xing Z. Liu & B.S. Lu, Mycosystema 6: 68 (1993)

Characteristics:

Colonies on CMA hyaline. Mycelium effuse, vegetative hyphae smooth-walled, hyaline, septate, and branched. Conidiophores hyaline, erect, septate, simple or with several branches normally at the apex, 230–460 μm long, 3–5 μm wide at the base, gradually tapering upwards to a width of 2–2.5 μm at the apex, bearing a single conidium or occasionally several conidia. Conidia hyaline, cymbiform, 0–3-septate, mostly 2-septate, 22.5–45 (27.2) × 10–20 (13.9) μm. The proportion of conidia with 0, 1, 2, and 3 septa is 4, 27, 55, 7 %, respectively. Chlamydospores present in aged cultures, in chain. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Beijing, Hainan, Henan, Sichuan, Yunnan)

Material examined:

YMF1.00028, isolated from soil in Lincang, Yunnan in 1999 by Lu Cao; JLCB, isolated from forest soil in Changbai Mountain, Jilin in 1999 by Ke-Qin Zhang; YMF1.00546, isolated from soil in Yinjiang, Yunnan in October 2002 by Jing Zhang. Permanent slide: L32–6

Notes:

This fungus most resembles A. scaphoides in its fusiform or boat-like shaped spores, but the conidia of A. microscaphoides is smaller than those of A. scaphoides. Although the conidia of A. scaphoides are 23–39 × 12–17 μm in Peach’s (1952) description covered the range of A. microscaphoides 23–39 × 8–15.5 μm in original description (Liu and Lu 1993), but the average length and width of conidia of A. scaphoides is much longer than that of A. microscaphoides according to our measurement of the conidia of the figure in Peach’s paper. (Fig. 3.27)

Arthrobotrys multiformis (Dowsett J. Reid & Kalkat) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 103 (1999)
Dactylella multiformis Dowsett J. Reid & Kalkat, Mycologia 76: 563 ( 1984)
Monacrosporium multiformis (Dowsett J. Reid & Kalkat) A. Rubner, Stud.Mycol.39 84 (1996)

Characteristics:

Colonies on CMA whitish, rapidly growing and extending to a diameter of 7–8 cm at 25 °C within 7 days. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, simple, erect, septate, 80–220 μm long, bearing a single conidium at the apex. Conidia elongate-fusiform, 4–12-septate, 47–198 × 7–20 μm, solitary. Conidia may raise to secondary conidiophores up to 50–120 μm long, on apices of which bearing clavate to cylindric-clavate, 0–1 septum, secondary conidia, 15–35 × 2.5–5 μm. Chlamydospores present in older cultures. Capturing nematodes by three dimension adhesive networks.

Distribution:

Canada (Manitoba), China (Hebei, Guizhou, Yunnan), Japan

Material examined:

CBS773.84 (A. multiformis), IFO32554 (A. iridis), 89019–1 (A. iridis), AN–1101 (A. iridis), provided by Dr. Xingzhong Liu. YMF 1.01477, isolated from soil in Xundian, Yunnan in April 2004 by Ye’e Hao. Permanent slide: YMF1.01477.

Notes:

A. multiformis resembles Dactylellina leptospora in its rather delicate, spreading mycelium and terminally produced, single conidia which are mostly straight, elongate-fusiform to cylindrical, and with many septa; both taxa produce secondary conidia. However, Da. leptospora traps nematodes by non-constricting rings and adhesive knobs, while A. multiformis traps by means of adhesive three-dimensional networks. Conidia of Da. leptospora are 40–105 × 4–5.8 μm, with 5–15 septa; those of A. multiformis, 35–90 × 4–7.5 μm with 4–12 septa. Secondary conidia of Da. leptospora are somewhat clavate 20–50 × 4–5.8 μm, 3–8-septate; those of A. multiformis are cylindric to clavate, 20–25 × 5 μm, 0–1-septate, and borne singly or on short sympodially proliferated denticles. A. multiformis, Dactylella ramiformis and Dactylella iridis share most morphological characteristics based on our observed strain, so we treat them as conspecific under the name A. multiformis. (Fig. 3.28)

Arthrobotrys nonseptata Z.F. Yu, S.F. Li & K.Q. Zhang, Mycotaxon 109: 249 (2009)

Arthrobotrys musiformis Drechsler, Mycologia 29 (4): 481 (1937)
Candelabrella musiformis (Drechsler), Rifai & R.C. Cooke, Trans. Br. mycol. Soc. 49 (1): 163 (1966)
Dactylella musiformis (Drechsler) Matsush., Microfungi of the Solomon Islands and Papua-New–Guinea (Osaka): 22 (1971)

Characteristics:

Colonies on CMA whitish, rapidly growing. Mycelium spreading, vegetative hyphae, septate, branched, mostly 1–10 μm wide. Conidiophores hyaline, septate, erect, not branched blow, 104–640 μm long, 5–7.5 μm wide at the base, gradually tapering upwards to a width of 2.5–5 μm near the apex, where are borne on divergent, slightly tapering, simple or branched sterigmata, mostly 1–2.5 μm wide, 3–35 μm long, usually 5–15 conidia in loose capitate arrangement. Conidia hyaline, ellipsoid, straight or slightly curved, broadly rounded at the wider distal end, tapering noticeably towards the slightly protruded base, 20–47.5 (30.9) × 7–12.5 (10.3) μm, 1-septate close to the base of the spore. Chlamydospores yellow, globose or less frequently ellipsoidal, mostly 14–22 μm in diameter. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Brazil (Sao Paulo), China (Anhui, Beijing, Guangxi, Guizhou, Hubei, Shangdong, Sichuan, Taiwan, Xizang, Yunnan), Ecuador (Tungurahua), France (Limousin), Netherlands (Den Haag, Meerdink–bos near Winterswijk), Nigeria (Ibadan), UK (Scotland), USA (Maryland, Virginia)

Material examined:

Z327, Z377, isolated from soil in Guiyang, Guizhou in 1992 by Ke-Qin Zhang; H101, H093, isolated from field soil in Kunming, Yunnan in 1991 by Ke-Qin Zhang; GZFJ–15, AHHS–22, isolated from soil in Fanjing Mountain, Guizhou and Huangshan Mountain, Anhui in 1996 by Ke-Qin Zhang; DL2–2, isolated from forest soil in Dali, Yunnan in September 2002 by Jing Zhang; XM43–1, isolated from forest soil in Xiangmi, Yunnan in 1999 by Yanju Bi; XZA–6, isolated from humus in Xizang in August 2000 by Minghe Mo; YMF1.00581, YMF1.00122, YMF1.00575, isolated from forest soil in Ruili and Lijiang, Yunnan in October 2002 by Jing Zhang. Permanent slide: 187.

Notes:

A. musiformis resembles Drechslerella dactyloides in having ellipsoid, straight or slightly curved conidia, but differs in trapping-devices. The former captures nematodes by three dimensional adhesive networks, while the later captures nematodes by constricting rings. A. musiformis also resembles A. javanica in candelabrum-like branching of the conidiophore and trapping-devices, but differs in conidia. In A. musiformis, conidia are ellipsoid, mostly slightly curved, 20–47.5 (30.9) × 7–12.5 (10.3) μm, while in A. javanica, conidia are 20–37.5 (27.9) × 7.5–10 (8.8) μm, narrowly obovoid or clavate.

Strain H093 can produce microconidiophores and microconidia from mycelium or from conidia. Microconidiophores 40–50 μm long, microconidia oviform, single-cell, 12–14 × 4.8 µm. These characters were not described in previous references, but other characters match A. musiformis. (Fig. 3.29)

Characteristics:

Colonies slow-growing on CMA medium, attaining less than 35 mm diameter in 10 days at 25 °C. Vegetative hyphae hyaline, septate, 3.5–4 μm wide, aerial mycelium sparse, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores erect, septate, unbranched, 40–120 μm high, 2–4 μm wide in the lower part, 1.5–2 μm wide at the apex, producing 3–10 conidia from retrogressive conidiogenous loci on conspicuous denticles at and near the apex. Conidia hyaline, aseptate, 11–16.8 × 5–6.6 μm, elongate ellipsoid, constricted at the base by forming a small truncate protuberance. Nematodes are captured by means of three dimensional adhesive networks.

Distribution:

China (Yunnan)

Material examined:

YMF1.01852, Yimen, Yunnan, Yimen, in Aug. 2006 by Z.F. Yu.

Notes:

There are five known species of Arthrobotrys with aseptate or occasionally 1-septate conidia. Conidia of A. amerospora (Schenck et al. 1977) are consistently non-septate, those of A. anomala (Barron and Davidson 1972), A. botryospora (Barron 1979) and A. yunnanensis (Mo et al. 2005) are occasionally 1-septate. A. nonseptata differs from other four species in conidial shape and size. Among four species, A. nonseptata most resembles A. yunnanensis in regard to conidial shape. Both species were anamorph state of Orbilia sp., and conidia vary in shape, but part conidia of both species are elongate, ellipsoid. In addition, the denticles of A. yunnanensis are longer than those of A. nonseptata. (Fig. 3.30)

Arthrobotrys oligospora Fresen., Beitr. Mykol. 1: 18 (1850)
Arthrobotrys superba var. oligospora (Fresen.) Coem.
Didymozoophaga oligospora (Fresen.) Soprunov & Galiulina, Mikrobiol., Reading 20: 493 (1951)

Arthrobotrys obovata K.Q. Zhang & Xing Z. Liu, in Zhang, Liu, Cao & Gao, Mycol. Res. 100 (5): 529 (1996)

Characteristics:

Colonies on CMA initially whitish and turned to tinged pink after about one month, rapidly growing, attaining a diameter of 9 cm within 5 days at 25 °C. Mycelium hyaline, vegetative hyphae septate, branched. Conidiophores single or branched, erect, septate, 200–400 μm long, 5–7.5 μm wide at the base, gradually tapering to 2.5–3 μm wide below the first node, branches up to 8–38 μm long, conidiogenous loci with denticle nodes; conidiophores usually continue development by repeated elongation and successive production of 2–9 additional denticle nodes, often containing 5–15 conidia in loose capitate arrangement. Conidia hyaline, obovoid, 1-septum in about one third from the basal end, broadly rounded at the apex, obconical at the base, not constricted at the septum, 28.5–32 (30) × 18–20.5 (20) μm. The basal cells are very small, usually 5–6.5 μm long, and the distal cells are much larger, usually 20.5–25.5 μm long. Chlamydospores absent. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Yunnan)

Material examined:

CBS618.95. YMF1.00011, isolated from forest soil in Fanjing Mountain, Guizhou in June 1994 by Ke-Qin Zhang. Permanent slide: FJ92.

Notes:

This fungus closely resembles A. cystosporia and A. perpasta in conidial shape and size but differs in conidiogenous loci and conidial arrangement. In A. cystosporia and A. perpasta, conidiogenous loci are simple denticles, and conidia are widely spaced arrangement, while in A. obovata, conidiogenous loci are denticle nodes and conidia are loose capitate arrangement. (Fig. 3.31)

Arthrobotrys polycephala (Drechsler) Rifai, Reinwardtia 7 (4): 371 (1968)
Dactylaria polycephala Drechsler, Mycologia 29: 530 (1937)
Woroninula polycephala (Drechsler) Mekht, Khishchnye Nematofagovye Griby— Gifomitsety (Baku): 110 (1979)

Characteristics:

Colonies on CMA whitish, rapidly growing and extending to a diameter of 10 cm at 25 °C within one week. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched, mostly 1.8–4.5 μm wide. Conidiophores hyaline, septate, at first erect, later often more or less procumbent, 90–270 μm long, 4–5 μm wide at the base, gradually tapering upwards to a width of 2.5–3 μm below the first denticle node producing 1–5 conidia, then following repeated elongation often giving rise successively to additional conidial clusters. Initially forming ellipsoidal-shaped conidia, hyaline, rounded at the distal end, somewhat acute at the base,1–3-septate, 12.5–25 (20) × 3–5 (4.5) μm; then forming fusoid-shaped conidia, 2–4-septate, occasionally 2-septate, often 4-septate, most often 3-septate, sometimes slightly constricted at the septa, 30–50 (45.1) × 8–16.5 (12.2) μm; proportion of conidia with 2, 3 and 4 septa is 3, 79 and 18, respectively. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Hubei, Xizang, Yunnan), Cuba, Germany (Berlin), USA (Maryland)

Material examined:

W7230–3–06, isolated from field soil in Wuhan, Hubei in February 2001 by Xuefeng Liu et al; XZA–9, isolated from forest soil in Xizang, in August 2000 by Minghe Mo; YMF1.00035, YMF1.00600, isolated from forest soil in Jiuzhaigou, Xichuan in April 2004 by Xuefeng Liu. Permanent slide: W7230–3–06.

Notes:

The conidia of A. polycephala slightly resemble those of A. musiformis in general shape, but differ in having larger and more abundant septate. The fungus was initially assigned to Dactylaria based on the plural septation of its conidia (Drechsler 1937). However, it was then transferred to Arthrobotrys based on trapping devices, nodose and repeatedly capitate forms of conidiophores (Rifai 1968). (Fig. 3.37)

Arthrobotrys pseudoclavata (Z.Q. Miao & Xing Z. Liu) J. Chen, L.L. Xu, B. Liu & Xing Z. Liu, Fungal Diversity 26 (1): 123 (2007)
Dactylella pseudoclavata Z.Q. Miao & Xing Z. Liu, Can. J. Bot. 81: 453 (2003)

Characteristics:

Colonies on CMA, slightly brown on top and light brown to yellowish below, effuse extending to a diameter of 7.5 cm at 25 °C within 7 days. Mycelium spreading, vegetative hyphae hyaline, septate, branched, prostrate, 2.5–7 μm wide. Conidiophores erect, simple or occasionally branched, hyaline, septate, 150–300 μm long, 6–7.5 μm wide at the base, gradually tapering upwards to a width of 4–5.5 μm at the apex. The conidiogenous cell produced 1–4 conidia holoblastically. Conidia 30–45 × 8–11 μm, obclavate, round to blunt at distal end, constricted into bottleneck shape at the base, with zero or one septum, which was generally at lower centre or at the septum. Some conidia broke into two parts at the septum. Chlamydospores were abundant in aged culture on PDA, intercalary or catenulate, yellowish to brown, globate or subglobate. Capturing nematodes by means of three dimensional adhesive networks.

Distribution

China (Beijing)

Material examined:

HMAS 84442, isolated from field soil in Haiding, Beijing in February 1998 by Zuoqing Miao.

Notes:

A. pseudoclavata is characterized by obclavate, 0–1-septate conidia with round distal end and bottleneck-shaped base, simple conidiophores bearing 1–4 conidia at apex, and adhesive networks as the nematode-trapping device. These characters can distinguish it from other Arthrobotrys species. (Fig. 3.38)

Arthrobotrys psychrophila (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Dactylaria psychrophila Drechsler, Mycologia 36 (2): 161 (1944)
Genicularia psychrophila (Drechsler) Rifai, Reinwardtia 7 (4): 367 (1968)
Geniculifera psychrophila (Drechsler) Rifai, Mycotaxon 2: 216 (1975)
Golovinia psychrophila (Drechsler) Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 151 (1979)
Monacrosporium psychrophilum (Drechsler) R.C. Cooke & C.H. Dickinson, Trans. Br. mycol. Soc. 48: 622 (1965)

Characteristics:

Mycelium spreading; vegetative hyphae hyaline, septate, mostly 2–6 μm wide. Conidiophores hyaline, erect, septate, mostly 150–500 μm high, 5–9 μm wide at the base, 2.5–4.5 μm wide at the apex, sometimes simple and sometimes bearing near the apex a branch (occasionally 2 branches) up to 35 μm long, often on giving rise terminally to 1–2 conidia elongating once or twice to produce 1 or 2 additional conidia, and thus frequently coming to bear 3 or 4 conidia in a loose head. Conidia hyaline, ellipsoidal or fusoid-ellipsoidal, rounded at the distal end, somewhat truncate at the proximal end, when developed under favorable conditions measuring mostly 46 to 70 μm (average 62.3 μm) in length and 21–29 μm (average 24.7 μm) in greatest width, containing from 1–5 cross-walls but mostly divided by 3 or cross-walls into 4–5 cells whereof one, as a rule– the penultimate cell usually in triseptate specimens and the median cell usually in quadriseptate specimens- greatly exceeds the others in size. Capturing nematodes by means of three dimensional adhesive networks.

Sexual state:

Orbilia auricolor (Bloxam ex Berk) Sacc., Syll. Fung., 8: 625,1889

Distribution:

USA.

Notes:

The description is based on the protologue. This species resembles A. oudemansii, but differs from the latter by mainly 3–4-septate conidia, while conidia of A. oudemansii are mainly 3-septate. (Fig. 3.39)

Arthrobotrys pyriformis (Juniper) Schenk, W.B. Kendr. & Pramer, Can. J. Bot. 55 (8): 984 (1977)
Dactylaria pyriformis Juniper, Trans. Br. Mycol. Soc. 37: 437 (1954)
Dactylariopsis pyriformis (Juniper) Mekht., Khishchnye Nematofagovye Griby— Gifomitsety (Baku): 119 (1979)

Characteristics:

Colonies on CMA whitish. Mycelium spreading, vegetative hyphae hyaline, septate, branched, 2–5 μm wide. Conidiophores erect, hyaline, septate, 150–550 μm long, 4–8 μm wide at the base, tapering upwards to a width of 2.5–4 μm at the apex with denticle nodes; conidiophores usually continue development by repeated elongation and successive production of 2–3 additional denticle nodes, often containing 4–5 conidia. Conidia hyaline, elongate-pyriform, broadly rounded at the distal end, 17–38 × 6.5–11.5 μm, mostly 2–3-septate, occasionally 1-septate. Chlamydospores thick-walled, globose or ellipsoidal, 20–35 10–2 μm, yellowish with dense globuliferous content. Capturing nematodes by three dimensional adhesive networks.

Distribution:

China (Yunnan), Canada (Quebec), Ecuador (Baños), Germany (Berlin), Netherlands (Noordoostpolder), UK (England)

Material examined:

YMF1.00018, isolated from forest soil in Shennongngjia, Hubei in 2003 by Wei Zhou; Z125, isolated from forest soil in Xishuangbanna, Yunnan in 1994 by Ke-Qin Zhang. Permanent slide: LH31.

Notes:

The specific epithet of A. pyriformis is based on the pyriform-shaped conidia. It resembles Dr. brochopaga in having 2–3-septate conidia, but differs in trapping devices and conidial shape. A. pyriformis produces elongate-oviform conidia and three dimensional adhesive networks while Dr. brochopaga produces cylindrical or elongate ellipsoidal conidia and constricting rings. Oorshot (1985) restudied the holotype (CBS204.83), and observed conidiophore branching, less expanded at the conidiogenous loci, and smaller conidia than in the original description (15–25 × 5–8 μm). The characters of our strain YMF1.00018 match well with the original description. (Fig. 3.40)

Arthrobotrys reticulata (Peach) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Dactylella reticulata Peach, Trans. Br. Mycol. Soc. 33 (1–2): 148 (1950)
Golovinia reticulata (Peach) Mekht., Khishchnye Nematofagovye Griby-Gifomisety (Baku): 143 (1979)
Monacrosporium reticulatum (Peach) R.C. Cooke & C.H. Dickinson, Trans. Br. Mycol. Soc. 48: 622 (1965)

Characteristics:

Colonies on CMA whitish. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched, 4–5 μm. Conidiophores hyaline, erect, septate, simple, only infrequently branched at the base, 250 μm long, bearing a single conidium on the apex. Conidia hyaline, ellipsoid, with one of the central cells being largest, 50–65 × 20–25 μm, mostly 4-septate, sometimes 5-septate. Chlamydospores present in aged cultures, in chains or clusters, globose to subglobose. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Guizhou, Hebei, Shanxi), UK (near Harpenden Common)

Material isolated:

FJ46, isolated from forest soil in Fanjing Mountain, Guizhou in 1994 by Ke-Qin Zhang;

Notes:

Our isolate matches the original description (Peach, 1950). This species can be distinguished from similar species by its fusiform and 5-septate conidia. (Fig. 3.41)

Arthrobotrys robusta Dudd., Trans. Br. mycol. Soc. 34 (4): 598 (1952) [1951]

Characteristics:

Colonies on CMA whitish, rapidly growing and extending to a diameter of 7.5 cm at 25 °C within one week. Mycelium spreading, vegetative hyphae hyaline, septate, branched, mostly 2–7 μm wide. Conidiophores erect, septate, branched, 200–300 μm long, 2–2.5 μm wide at the base, tapering upwards to a width of 1–2 μm at the slightly expanded apex, where on forming a compact of conidia (up to 6). Conidia oblong-pyriform, hyaline, 20–27.5 (24.4) × 7.5–12.5 (10.8) μm, 1-septate at the centre of spore. Chlamydospores not observed. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Beijing, Guizhou, Hebei, Heilongjiang, Jilin, Liaoning, Neimeng, Shanxi, Yunnan), Canada (Quebec), Ecuador (Baños), Germany (Berlin), Netherlands (Noordoostpolder), UK (England).

Material examined:

Z241, ZX41, isolated from forest soil in Guizhou and Shanxi in 1991 by Ke-Qin Zhang; ZS–3–2, isolated from forest soil in Xishan, Yunnan in June 1999 by Lu Cao; DQ4–8–2, isolated from soil in Xundian, Yunnan in September 2002 by Jing Zhang. Permanent slide: XS–3–2.

Notes:

A. robusta resembles A. superba and A. oligospora in conidia, but differs in the freely branched conidiophores and in the absence of nodal development of conidia in whorls down the conidiophores. A. robusta also resembles A. cladodes in its general habit, differing from the former in both size of conidia and the absence of enlarged storage hyphae. (Fig. 3.42)

Arthrobotrys rutgeriense (R.C. Cooke & Pramer) Z.F. Yu, comb.nov
Monacrosporium rutgeriense R.C. Cooke & Pramer, [as ‘rutgeriensis’] Phytopathology 58: 544, 1968
MB 804793

Characteristics:

Colonies on CMA white. Vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, erect, simple, septate, 67.5–350 μm long, 3–8 μm wide at the base, gradually tapering upwards to a width of 2–3 μm at the apex, bearing a single conidium. Sometimes conidiophores branched at the apex and two conidia were each borne singly and terminally on these branches, which up to 15 μm long. Conidia hyaline, globose to broadly turbinate, 27–47.5 (32.2) × 17.5–27.5 (22) μm, rounded at the distal end and tapered proximally to a narrow, truncate at the base, 2–3-septate. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Xizang, Yunnan), USA

Material examined:

⑨–13, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; XZM–9, isolated from soil in Xizang in August 2000 by Minghe Mo; YMF1.00040, isolated from soil in Baoshan, Yunnan in October 2002 by Jing Zhang. Permanent slide: ⑨–13

Notes:

A. rutgeriense resembles A. eudermata in conidial shape and septation, but differs markedly from it in conidial size, although there is a slight overlap between the two species. A. rutgeriense can be distinguished from A. cookedickinson in having predominantly 2–3-septate conidia in contrast to mainly 2-septate conidia in the latter species. (Fig. 3.43)

Arthrobotrys salina (R.C. Cooke & C.H. Dickinson) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Monacrosporium salinum R.C. Cooke & C.H. Dickinson, Trans. Br. Mycol. Soc. 48: 626 (1965)
Golovinia salinum (R.C. Cooke & C.H. Dickinson)Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 145 (1979)

Characteristics:

Single conidium produce from apex of conidiophores; conidia fusiform to ellipsoid, 32.5–52.5 × 12.5–17.5 μm, 0–4-septate, mainly 3-septate; chlamydospores not observed; capturing nematodes by means of three dimensional adhesive networks.

Distribution:

UK.

Notes:

The description is based on the protologue. This species varies in shape, septa and size of conidia, which result in difficulty of species identification. (Fig. 3.44)

Arthrobotrys scaphoides (Peach) S. Schenck, W.B. Kendr. & Pramer, Can. J. Bot. 55 (8): 984 (1977)
Dactylaria scaphoides Peach, Trans. Br. Mycol. Soc.35 (1): 19 (1952)
Monacrosporium scaphoides (Peach) Xing Z. Liu & K.Q. Zhang, Mycol. Res. 98 (8): 865 (1994)
Woroninula scaphoides (Peach) Mekht, Khishchnye Nematofagovye Griby-Gifomitsety (Baku): 113 (1979)

Characteristics:

Mycelium spreading, growing slowly, reaching 30 mm in diameter at 28 °C after 12 days. Vegetative hyphae hyaline, septate, 4–6 μm wide. Conidiophores erect, hyaline and septate, unbranched, 4.5–5.6 μm wide at base and tapering to a width of 4–4.5 μm, at a distance of 80–200 μm from the base producing 1–6 conidia, occasionally up to 10 conidia, in a loose capitate arrangement, then following repeated elongation often giving successively rise to up to 3 additional conidial clusters by branching at or just below slightly swollen warted nodules, producing more or less geniculate conidiophores up to 365–430 μm long. Conidia hyaline, 36.6–79.3 (57) × 11–17.5 (14) μm (Chinese strain), (50–)60–80 (–86) × (13–)14–15 (–16) μm (Dutch strain, both vital state in water), fusiform, not or slightly curved, 1–6-septate, mainly 2–3-septate, the proportion of conidia with 1, 2, 3, 4, 5 and 6 septa is 1.3, 48.8, 37.5, 10, 1.3 and 1.3 % respectively (Chinese strain), 2–3 (–4)-septate (Dutch strain), central cell mostly distinctly longer and wider than other cells. Three dimensional adhesive networks observed when nematodes added. Chlamydospores not observed in cultures.

Distribution:

China, Netherlands

Material examined:

YMF1.01895: Gansu Province, Jiuquan City, alt. 2450 m, from soil, under Malus asiatica Nakai (Rosaceae), from a private plantation. VIII.2006, YMF 1.01895, permanent slide culture (YMF 1.01895); H.B. 6972: The Netherlands: Zeeland, old harbor facing the Hertoginpolder, Verdronken Land van Saeftinghe, most eastern part, alt. 0 m, on previous year’s leaves of Scirpus maritimus L. (Cyperaceae), 23.III.2001,G. Van Ryckegem (H.B. 6972b, dry specimen, associated with A. oudemansii M. Scholler et al. and its sexual state).

Notes:

Within A. scaphoides, the Chinese strain shows a closer relationship to strain H.B. 6972: the ITS rDNA sequence analysis demonstrates that there is 99.6 % similarity between them (2 nucleotide variance in ITS1-5.8s-ITS2 region), but 98.7 % between the Chinese strain and CBS 226.52 (type strain, 7 nucleotide variances), and 99 % between the strain from Scirpus and the type strain from Typha (5 nucleotide variance). Between the Chinese strain of A. scaphoides and other morphologically close species, the similarity is 84.2 % to A. microscaphoides Xing Z. Liu & B.S. Lu, 84.9 % to A. thaumasia (Drechsler) S. Schenck et al., (CBS 322.94), and 85.7 % to A. gampsospora. (Fig. 3.45)

Arthrobotrys shahriari (Mekht.) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Candelabrella shahriari Mekht, Mycol. Res. 101: 334 (1997)

Characteristics:

Colony growing rapidly, aerial mycelium initially white, becoming pale cream. Conidiophores erect, simple or branched and the apex candelabrum-like with 3–9 branches each bearing a conidium at the apex. The conidiophores rarely recommenced growth after the group of conidia had been produced and a second head was then formed above the first. Conidia elongate-obovoid or elongate-ellipsoidal, straight or sometimes curved, rounded distally and tapering proximally to a truncate base, 1-septate, 33.5–57 × 11–15.5 μm. Globose terminal chlamydospores also formed and adhesive traps formed rarely in pure culture. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Azerbaijan (Tabriz)

Notes:

The description is based on the protologue. This species can be distinguished from other similar species by the candelabrum-like apex of the conidiophores and 1-septate, elongate-obovoid or elongate-ellipsoidal conidia. (Fig. 3.46)

Arthrobotrys shizishanna (X.F. Liu & K.Q. Zhang) J. Chen, L.L. Xu, B. Liu, Fungal Diversity 26 (1): 124 (2007)
Dactylella shizishanna X.F. Liu & K.Q. Zhang, Fungal Diversity 14: 104 (2003)

Characteristics:

Colonies on CMA whitish, slow growing and extending to a diameter of 3.5 cm within 15 days at 25℃. Aerial hyphae scant, hyaline, septate, branching, commonly 2.5–3.7 μm wide. Conidiophores growing from mycelium on the substratum, single, erect, rarely branched, 35–200 μm long, 1.5–2.5 μm wide at the base, tapering upwards gradually to a distal width of 0.5–1 μm, bearing a single conidium. Conidia hyaline, clavate, gradually narrowing at the basal end, obtuse at the distal end, straight or sometimes slightly curved, sometimes constricted at the septa, 2–9-septate, mostly 3–7-septate, 22.5–73.8 (50.6) × 5–10 (6.6) μm. The proportion of conidia with 3, 4, 5, 6 and 7 septa is 10, 30, 33, 18 and 6 %, respectively. Chlamydospores present in aged cultures. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Hubei)

Material examined:

YMF1.00022, isolated from field soil in Shizishan, Hubei in February 2001 by Xuefeng Liu.

Notes:

A. shizishanna is easily distinguished other Arthrobotrys species because having the most septate conidia. (Fig. 3.47)

Arthrobotrys sinensis (Xing Z. Liu & K.Q. Zhang) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Monacrosporium sinense Xing Z. Liu & K.Q. Zhang, Mycol. Res. 98: 863 (1994)

Characteristics:

Colonies growing on CMA rapidly, attaining a diameter of 6 cm within 7 days at 25 °C, with sparse aerial hyphae. Vegetative hyphae hyaline, septate, branched, mostly 2.5–9.5 μm wide. Conidiophores hyaline, simple, erect, septate, occasionally branched, mostly 200–500 μm long, 4.5–5.5 μm wide at the base, tapering to 2.5–3 μm wide at the apex, bearing a single conidium. Conidia hyaline, subsphaerical to obovoid, 1–3-septate, 37 % of conidia 3-septate, 42 % 2-septate and 21 % 1-septate, 23.5–30 (27.6) × 17–25 (20) μm. Chlamydospores sphaerical to ellipsoidal, terminal to intercalary in chains, mostly 20–24 × 17–25 μm. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Jiangxi, Xizang, Yunnan)

Material examined:

YMF1.00025, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; XZM–10, isolated from soil in Xizang in August 2000 by Minghe Mo. Permanent slide: CK9–1

Notes:

This fungus closely resembles A. cookedickinson and A. indica in its relatively small conidia and conidial shape, but differs in size of conidia. In A. cookedickinson, conidia are 32.5–50 × 14–23 μm, in A. indica conidia are 22–30 × 14–20 μm, while in A. sinense, conidia are 25–30.5 × 15–18 μm. (Fig. 3.48)

Arthrobotrys sphaeroides (Castaner) Z.F. Yu, comb. nov.
Monacrosporium sphaeroides Castaner, Am. Midl. Nat. 80: 282 (1968)
MB804795

Characteristics:

Colonies on CMA white, growing rapidly. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched, mostly 2–5 μm wide. Conidiophores hyaline, erect, simple, septate, 200–460 μm long, 5–8 μm wide at the base, gradually tapering upwards to a width of 2.5–3 μm at the apex, bearing a single conidium. Conidia hyaline, sphaeroid to obovoid, 20–44 (32) × 17–25 (20.4) μm, 0–3-septate. Chlamydospores in chains or clusters. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Guizhou, Xizang, Yunnan), USA

Material examined:

YMF1.00030, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; YMF1.00539, isolated from soil in Baoshan, Yunnan in September by Jing Zhang. Permanent slide: ④–5–1.

Notes:

This fungus mostly resembles A. cookedickinson. In A. cookedickinson, conidiophores are simple or branched, and conidia are clavate to turbinate and 32.5–50 × 14–23 μm. In A. sphaeroides conidiophores are always simple, conidia are sphaeroid to obovoid and 28–42 × 19–29 μm. Comparisons between A. cookedickinson and A. sphaeroides indicate that the latter is sufficiently different to be considered a distinct species. (Fig. 3.49)

Arthrobotrys superba Corda, Pracht-Fl. Eur. Schimmelbild.: 43 (1839)
Didymozoophaga superba (Corda) Soprunov & Galiulina, Mikobiology, Reading 20: 493 (1951)

Characteristics:

Colonies on CMA whitish to reddish, rapidly growing. Mycelium dense, spreading, vegetative hyphae hyaline branched, septate. Conidiophores hyaline, smooth, 6–9-septate, rarely branched, erect, 180–600 μm long, 2.5–7.5 μm wide, apex swelling, bearing 20–39 conidia. Conidia elliptical, 1-septate at the centre of spore, slightly constricted at the septum, broadly rounded at the distal end, 7.5–27.5 (15.8) × 5–10.5 (6.6) μm. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Guizhou, Hainan, Hubei, Jilin, Tianjing, Xizang, Yunnan), cosmopolitan.

Material examined:

Z19, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; JLCB–1, isolated from forest soil in Changbai Mountain, Jilin in 1996 by Ke-Qin Zhang; LT–10, isolated from soil in Huaguoshan, Lincang in 1999 by Yanju Bi; J–1qz07, isolated from soil in Liqizhuang, Tianjing in 2000 by Wenpeng Li; XZA–10, isolated from pasture soil in Xizang in August 2000 by Minghe Mo; YMF1.00016, DQ4–2, isolated from forest soil in Xundian, Yunnan in September 2002 by Jing Zhang. Permanent slide: ⑨–19.

Notes:

Arthrobotrys superba was established as the type species of Arthrobotrys (Corda 1839), which is the asexual state of Orbilia fimicola (Pfister 1994). Arthrobotrys superba resembles A. conoides and A. oligospora in most morphological characters except in conidia shape and the position of septum. In A. superba conidia are elliptical and 1-septate at the centre. In A. conoides conidia are elongate obconical, 1-septate about one third from the basal end, constricted at the septum. In A. oligospora conidia are obovoid, 1-septate near the base of the spore, and constricted at the septum. (Fig. 3.50)

Arthrobotrys tabrizica (Mekht.) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 104 (1999)
Nematophagus tabrizicus Mekht, Mycol.Res.102: 683 (1998)

Characteristics:

Colony growing rapidly, velvety, initially white, changing through pale pink to intensive pink after 2 wk. Conidiophores simple, erect, branched, curved, with several swollen to distinctly denticulate conidiogenous regions forming close conidial heads; these proliferating to form additional conidiogenous regions. Conidia elongate-ovate to elongate-doliform or ellipsoidal, 1–2 (–3)-septate, 28.5–56 × 11.5–22.5 μm, with a pronounced protuberant base. Ellipsoidal to cylindrical intercalary chlamydospores present. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Azeraijan (Tabriz)

Notes:

The description is based on the protologue. This species produces simple or branched conidiophores with several conidial clusters. Conidia are 1–3-septate; 2-septate conidia are more dominant in the original isolation plate than when the fungus was grown on malt agar. (Fig. 3.51)

Arthrobotrys thaumasia (Drechsler) S. Schenck, W.B. Kendr. & Pramer, Can. J. Bot. 55 (8): 984 (1977)
Dactylaria thaumasia Drechsler, Mycologia 29 (4): 522 (1937)
Candelabrella thaumasia (Drechsler)Rifai, Reinwardtia 7 (4): 369 (1968)
Golovinia thaumasia (Drechsler) Mekht., Mikol. Fitopatol. 1: 276 (1967)
Monacrosporium thaumasium (Drechsler) de Hoog & van Oorschot [as ‘thaumasia’], Stud. Mycol. 26: 120 (1985)

Characteristics:

Colonies on CMA white to reddish. Mycelium spreading, vegetative hyphae hyaline, septate, branched, 2–8 μm wide. Conidiophores hyaline, erect, septate, 195–460 μm long, 4–8 μm wide at the base, gradually tapering upwards to a width of 2–4 μm at the apex, simple or often somewhat branched near the apex, and there borne on blunt sterigmata, mostly 2–10 μm long and 2–3 μm wide, usually 3–15, rarely up to 25 conidia in loose capitate arrangement. Conidia hyaline, top-shaped, rounded at the apex, tapering towards the frequently somewhat protruding truncate base, 30–60 (36.2) × 15–30 (20.2) μm, 1–4-septate, mostly 3-septate. Chlamydospores yellow, globose or ellipsoidal. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Anhui, Beijing, Guangdong, Guizhou, Hebei, HuBei, Hunan, Jiangsu, Xizang, Yunnan, Zhejiang), Baukina Faso (Houet), Germany (Berlin–Dahlem), Netherlands (Schipborg), Thailand, UK (England), USA (Norfolk)

Material examined:

L3–5, isolated from soil in Licang, Yunnan in 1999 by Yanju Bi; XZM–11, isolated from soil in Xizang in August 2000 by Minghe Mo; YMF1.00026, YMF1.00547, YMF1.00586, isolated from soil in Baoshan, Yunnan in October 2002 by Jing Zhang; Sjz3.11.20, isolated from soil in Huaxi, Guiyang in 1996 by Ke-Qin Zhang. Permanent slide: Sjz3.11.20

Notes:

Arthrobotrys thaumasia resembles A. elegans in conidial shape and number of septa, but differs in conidiophores and conidial length. The conidia of A. thaumasia are longer than those of A. elegans. Moreover, in A. thaumasia, conidiophores branch near the apex, bearing blunt sterigmata with 3–15 conidia in a loose capitate arrangement, while in A. elegans conidiophores bear a single conidium at the apex, or occasionally form a branch near the apex with a conidium. (Fig. 3.52)

Arthrobotrys vermicola (R.C. Cooke & Satchuth.) Rifai, Reinwardtia 7 (4): 371 (1968)
Dactylaria vermicola R.C. Cooke & Satchuth., Trans. Br. Mycol. Soc. 49: 27 (1966)
Nematophagus vermicola (R.C. Cooke & Satchuth.) Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 105 (1979)

Characteristics:

Colonies on CMA whitish. Mycelium spreading, vegetative hyphae hyaline, septate, branched. Conidiophores erect, unbranched, septate, 140–470 μm long, forming 3–6 conidia in a loose capitate arrangement. Each conidium is formed on a small protuberance. The conidiophores often recommence growth after the first group of conidia had been produced, and a second head is then formed about 75 μm above the first. This process is repeated so that three to four groups of conidia are produced on each conidiophore, the latter then becoming somewhat geniculate. Conidia elongate-ellipsoidal to broadly fusiform, hyaline, 25–50 × 17.5–25 μm, bluntly rounded distally and tapering proximally to a narrow truncate base, 1–3-septate; proportion of conidia with 1, 2 and 3 septa is 4, 64 and 32 %, respectively. In 2-septate conidia the median cell, and in 3-septate conidia the penultimate cell, is usually larger than the others. Very rarely a 4-septate conidium was observed. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

Cosmopolitan

Material examined:

Z296, Z290, Z279–1, isolated from soil in Beijing, and Guiyang, Guizhou during 1991–1992 by Ke-Qin Zhang; YNBN–2, isolated from forest soil in Xishuangbanna, Yunnan in 1996 by Ke-Qin Zhang; J31–1, isolated from soil in Jianshui, Yunnan in 1999 by Yanju Bi; BS3–35, isolated from soil in Baoshan, Yunnan in October 2002 by Jing Zhang; YMF1.00533, YMF1.00534, YMF1.00554, from soil in Dehong, Yunnan in July 2003 by Hong Luo. Permanent slide: BS3–35.

Notes:

Arthrobotrys vermicola resembles A. guizhouensis (Zhang 1994) in the conidial shape and trapping devices, but differs in conidia septa and conidiophore form. In A. vermicola, conidia are mostly 2–3-septate, produced along the conidiophores, with 3–6 conidia being located at each denticle node of the unbranched conidiophores in a loose capitate arrangement. In A. guizhouensis, conidia are mostly 1-septate, produced at the irregular expanded apex of the branched conidiophores. (Fig. 3.53)

Arthrobotrys yunnanensis M.H. Mo & K.Q. Zhang, Fungal Diversity 18: 109 (2005)

Characteristics:

Colonies growing rapidly on CMA and attaining 6 cm diameter in 5 days at 28ºC and mycelia spreading at the rate of 0.5 cm per 24 h, conidiophores and conidia are produced after 4 days. Mycelium scanty, spreading, vegetative hyphae hyaline, septate and branched, mostly 2–4 µm wide. Conidiophores hyaline, erect, septate, simple, frequently 60–200 µm long, 2–5 µm wide at the base and 1.5–2.4 µm at the apex, producing 1–5 conidia singly from conidiogenous loci on conspicuous denticles at and near the apex. Conidia hyaline, elongate ellipsoid-cylindrical or slightly clavate, broadly rounded at the apex, rounded to truncate at the narrowed base, sometimes constricted gradually at the distal part of conidia, usually aseptate, occasional 1-septate (< 5 %) at the centre, 17.5–32.5 (22.6) × 2.75–7.5 (5.5) µm. Chlamydospores sphaerical to ellipsoidal, intercalary. Capturing nematodes by means of three dimensional adhesive networks.

Distribution:

China (Yunnan)

Material examined:

MF1.00593, isolated from soil in Yuliang, Yunnan in August 2003 by Minghe Mo.

Notes:

Arthrobotrys yunnanensis differs from the three species of Arthrobotrys which form aseptate, or occasionally 1-septate conidia, A. anomala, A. amerospora and A. botryospora. Arthrobotrys yunnanensis is characterized by predominantly elongate ellipsoid-cylindrical or slightly clavate, non-septate conidia which are borne on distinct and long denticles. Arthrobotrys yunnanensis and A. anomala have similar conidial shapes, but differ in the size of conidia. The conidia of A. anomala form one septum only when detached, while in the former species they are aseptate when detached. Arthrobotrys yunnanensis is easy to distinguish from A. botryospora and A. amerospora by their different conidia and conidiophores (modification at apex). Furthermore, unlike A. botryospora, A. yunnanensis does not capture nematodes by adhesive hyphae, and unlike A. amerospora, which only produces aseptate conidia, A. yunnanensis occasionally produces 1-septate conidia. (Fig. 3.54)

Species of the genus Dactylellina

Dactylellina arcuata (Scheuer & J. Webster) Ying Yang & Xing Z. Liu, Mycotaxon 97: 158 (2006)
Dactylella arcuata Scheuer & J. Webster, Mycol. Res. 94: 720 (1990)
Arthrobotrys arcuata (Scheuer & J. Webster) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Gamsylella arcuata (Scheuer & J. Webster) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 108 (1999)
Monacrosporium arcuata (Scheuer & J. Webster) A. Rubner, Stud. Mycol.39: 49 (1996)

Dactylellina M. Morelet, emend. M. Scholler, Hagedorn & A. Rubner
Type species: Dactylellina leptospora (Drechsler) M. Morelet-Bull. Soc. Sci. Nat. Archéol. Toulon Var 178: 6 (1968)
Dactylella leptospora Drechsler, Mycologia 29: 507 (1937)
Dactylosporium Mekht. (1967) [non Harz 1871] (nom. illeg., Art. 53 ICBN)
Type species: Dactylosporium leptosporum (Drechsler) Mekht., Mikol. Fitopatol. 1: 278 (1967)
Dactylella leptospora Drechsler, Mycologia 29: 507 (1937).
Kafiaddinia Mekht. (1978)
Type species: Kafiaddinia fusarispora Mekht., Mikol. Fitopatol.12: 8 (1978).
Laridospora Nawawi, (1976)
Type species: Laridospora appendiculata (Anastasiou) Nawawi— Trans. Br. Mycol. Soc. 66: 344 (1976)
Dactylella appendiculata Anastasiou— Pacif. Sci. 18: 202 (1964)

Characteristics:

Mycelium slow-growing. Hyphae septate, branching, hyaline. Saprotrophic or predatory by trapping nematodes or other animals by means of stalked adhesive knobs, sometimes in combination with stalked three-celled non-constricting rings. Traps generally spontaneously formed. Conidiophores mostly simple; branches, when present, often near the apex, apex mostly simple without modifications or sometimes with short denticles. Conidia either formed singly or in clusters on the apex of the conidiophore, holoblastic, hyaline, 1–7 (15) septate, mostly cylindrical, ellipsoidal, fusiform or spindle-shaped, rarely clavate or obconical. Microconidia and microconidiophores very rarely formed. Chlamydospores absent. Sexual state belonging to the genus Orbilia Fr. (Helotiales).

Key to Species of Dactylellina

1. Trapping organs adhesive knobs or knobs and non-constricting rings 5

1. Trapping organs others 2

2. Trapping organs simple two-dimension networks D. gephyropaga

2. Trapping organs adhesive branches, verruca, adhesive knobs and networks 3

3. Trapping organs adhesive branches D. cionopaga

3. Trapping organs adhesive verruca, knobs and networks 4

4. Trapping organs adhesive verruca D. robustum

4. Trapping organs knobs and networks D. arcuata

5. Trapping organs adhesive knobs and non-constricting rings 6

5. Trapping organs adhesive knobs 10

6. Near apex of conidiophores producing short branches, with conidia in strikingly loose capitate arrangement D. candidum

6. Conidia singly grows at apices of conidiophores, or at apices of subapical lateral branches 7

7. Conidia elongate-fusiform to cylindrical, with 5-15 septa D. leptospora

7. Conidia fusiform, mostly 4 or 5-septate 8

8. Conidia 3–6-septate, mostly 4 septate, largest cell not obvious D. sichuanensis

8. Conidia with largest cell 9

9. Conidia 2–4-septate, mostly 4-septate D. lysipaga

9. Conidia 3–8-septate, mostly 5-septate D. illaqueata

10.Adhesive unstalked, growing out to form branches, conidia with mostly 3-4 septa D. phymatopaga

10. Adhesive stalked or with short stalk 11

11.Conidiophores with apical cluster of conidia or as well as intercalary cluster, conidia arranged into capitate heads 12

11. Conidiophores unbranched, or occasionally with very short subapical lateral branches, conidia singly arranged 18

12. Conidiophores with apical cluster of conidia as well as intercalary cluster

D. entomopaga

12. Conidiophores with apical cluster of conidia 15

13. Conidiophores branched, which apex with denticles or sterigmata 14

13. Conidiophores unbranched 18

14. Conidia obovoid to elongate-cylindrical, 0–4-septate, mostly 3-septate

D. hertziana

14. Conidia ovoid to clavate, 1-septate D. ferox

15.Conidiophore of the candelabrelloid type D. huisuniana

15. Apex of conidiophores with sterigmata, without intercalary cluster of conidia 16

16. Conidia cylindrical D. haptospora

16. Conidia not cylindrical 17

17. Conidia fusiform, mostly 3-septate, adhesive knobs joined together to form loops

D. lobata

17. Conidia elongate-fusiform or clavate, straight or curve, mostly 6–8-septa

D. daliensis

18. Conidia typically fusiform 21

18. Conidia fusiform to other type 19

19. Distally end of conidia bluntly rounded 20

19. Conidia fusiform to cylindrical, mostly 4–7-septate D. formosana

20. Conidia obconical to clavate, distally end bluntly rounded, 3-septate

D. asthenopaga

20. Conidia ellipsoid to fusiform, 2-4-septate D. mammillata

21. Conidia 1–3-septate, often with thorn-like appendage D. appendiculata

21.Conidia with more than 2 septa 22

22. Shape of conidia varies on CMA, with multiform conidia D. mutabilis

22. Conidia mostly fusiform 23

23. Conidia 4–9-septate, mainly 6–7-septate D. multiseptatum

23. Conidia mostly 4–septate or 2–3-septate 24

24. Conidia mostly 2–-septate 25

24. Conidia mostly 4–septate 26

25. Conidia 3–4-septate, mostly 2–3-septate, 29.5-48.7 × 10.7-15.4 μm D. drechsleri

25. Conidia 3–5-septa, mostly with 3 septa, with shorter stalk adhesive knobs

D. quercus

26. Conidia relatively long, conidia 1–6-septate, mostly 4-septate, 56-97 × 8.5-16

D. copepodii

26. Conidia about 50 μm long 27

27. Conidia 3–5-septate, mostly 4-septate, 33-50 (43.7) × 7.4-13.3 (10.7) D. parvicolla

27. Conidia 2–4-septate, mostly 4 septate, 37.5-62 × 8.7-19.3 D. ellipspspora

Accepted Species of Dactylellina

Dactylellina appendiculata (Anastasiou) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 110 (1999)
Dactylella appendiculata Anastasiou, Pacif. Sci. 18: 202 (1964)
Monacrosporium tentaculatum A. Rubner &W. Gams, Stud. Mycol.39: 97 (1996)
Laridospora appendiculata (Anastasiou) Nawawi, Trans. Br. Mycol. Soc. 66 (2): 344 (1976)

Characteristics:

Conidia fusiform, often with thorn on it, 20–59 μm long, 10–24 μm wide, 1–3-septate. Capturing nematodes by adhesive hyphae.

Distribution:

Russia

Notes:

This species has not been reported from other regions since it was first reported from Russia. The type strain cannot be located, but we still treat it as an accepted species. (Fig. 3.55)

Characteristics:

Mycelium colourless, growing rapidly on 0.1 % malt extract agar. Conidiophores colourless, single, septate, erect, bearing only one conidium at the apex or a bundle of 2–8 conidia on denticles or short branches. Occasionally an additional ‘whorl’ of conidia formed around the central of conidiophores. Conidia colourless, usually 3-septate, fusiform, widest below the centre (30–)35–54 × 4–6 μm; end cells longer than central cells. Occasionally 2 septa conidia with cells of about equal length were found. Capturing nematodes by adhesive anastomotic branches.

Distribution:

UK.

Notes:

The description is based on the protologue. This species differs from other species of Dactylellina by its special trapping device. (Fig. 3.56)

Dactylellina asthenopaga (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 110 (1999)
Dactylella asthenopaga Drechsler, Mycologia 29: 498 (1937)
Dactylariopsis asthenopaga (Drechsler) Mekht., Mikol Fitopatol, 1: 279 (1967)
Monacrosporium asthenopaga (Drechsler) A. Rubner, Stud. Mycol. 39: 50 (1996)

Characteristic:

Conidiophores hyaline, septate, erect, 100–200 μm, mostly 125–175 μm high, 2.5–4 μm wide at the base, tapering gradually upwards to a width of approximately 1.5 μm, mostly unbranched and terminating in a single conidium, but occasionally giving off one or two branches some distance below the apex, and then bearing two or three conidia. Conidia hyaline, obconical or clavate, truncate at the narrow proximal end, broadly rounded at the distal end, 20–46 μm, mostly 26–36 μm (average 31.5 μm) long, 6.5–9.5 μm (average 8.2 μm)wide, containing 1–5-septa, but most often and most typically containing 3 septa, the basal of the 4 cells then delimited averaging about 8 μm in length, the antepenultimate cell about 7.5 μm, the penultimate cell about 9.8 μm, and the apical cell about 6.2 μm. Capturing nematodes by adhesive knobs.

Distribution:

Australia, Netherlands, UK.

Notes:

The description is based on the protologue. Within Dactylellina species which have adhesive knobs as trapping device, Da. asthenopaga is characterized by rarely unbranched conidiophores, and obconical or clavate conidia. (Fig. 3.57)

Dactylellina candidum (Nees) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Dactylium candidum Nees, Syst Pilze Schw 58, 1816: Fries Syst. mycol. 3: 44, 829
Arthrobotrys candida (Nees) S. Schenck, W.B. Kendr. & Pramer. Can. J. Bot. 55 (8): 982 (1977)
Candelabrella candida (Nees) Rifai, Reinwardtia 7 (4): 369 (1968)
Dactylaria candida (Nees) de Hoog, Stud. Mycol. 26: 102 (1886)
Dactylaria candida Nees, Syst. Pilze (Würzburg): 58 (1816) [1816–17]
Monacrosporium candidum (Nees) Xing Z. Liu & K.Q. Zhang, Mycol. Res. 98 (8): 864 (1996)
Dactylaria haptotyla Drechsler, Mycologia 42: 48, 1950
Monacrosporium yunnanense K.Q. Zhang, Xing Z. Liu & L. Cao, Mycol Res 100: 275 (1996)
Dactylellina yunnanensis (K.Q. Zhang, Xing Z. Liu & L. Cao) M. Scholler, Sydowia 51: 108 (1999)
Monacrosporium chiuanum Xing Z. Liu & K.Q. Zhang, Mycol. Res. 98: 863, 1994

Characteristics:

Colonies hyaline initially and turned whitish or faintly pink after 15 days of incubation on CMA and extending a diameter of 4 cm at 25℃ within 10 days. Mycelium hyaline, scanty, vegetative hyphae septate and branched. Conidiophores hyaline, erect, 5–7-septate, branched, 100–335 μm long, 2–3.7 μm wide at the base, gradually tapering upwards to a distal width of 1–2 μm, initially bearing a single terminal conidium, later often forming 2–12 (mostly 3–5) short branches near the apex with conidia in strikingly loose capitate arrangement. Conidia hyaline, narrow spindle-shaped or fusoid, gradually narrowing at the basal end, truncate at the base, 2–5-septate, mainly 4-septate, 27.5–57.5 (35) × 7.5–12.5 (9) μm. The proportion of conidia with 2, 3, 4 and 5 septa is 2, 10, 81 and 7 %, respectively. Chlamydospores not observed in cultures. The fungus produces two types of trapping organ: non-constricting ring and adhesive knobs.

Distribution:

worldwide.

Material examined:

D9-1, D12-1, isolated from soil in Wuding, Yunnan in 1999 by Yanju Bi; YMF1.00543, isolated from forest foil in Lijiang, Yunnan in October 2002 by Jing Zhang; YMF1.00036, isolated from soil in Zhongdian, Yunnan in 1999 by Lu Cao; YMF1.000579, isolated from forest soil in E’ mei Mountain, Sichuan in 2002 by Jinshi Deng. Permanent slide: DH5-5.

Notes:

Rubner (1996) treated Monacrosporium candidum, M. haptotylum and M. sclerohyphum as conspecific under the name M. haptotylum. M. yunnanense K.Q. Zhang, X.Z. Liu & L. Cao is similar to M. candidum in having spindle-shaped, mostly 4-septate conidia, and branched conidiophores, bearing 3–10 conidia in a loose capitate arrangement. The only difference being that M. candidum and M. yunnanense form both stalked adhesive knobs and non-constricting rings, while M. haptotylum and M. sclerohyphum form only stalked adhesive knobs. These four taxa are phylogenetically closely related receiving high support, based on the rDNA, β-tubulin and combined datasets and this grouping agrees well with the morphological characters of the taxa (Li et al. 2005). These four taxa can therefore be considered as conspecific and should be named Da. candidum based on our results.

No material of M. chiuanum could be obtained to study the relationship with other related species based on molecular analyses. Comparing the morphological characters of M. chiuanum from original description with M. candidum, M. yunnanense, M. haptotylum and M. sclerohyphum, the difference among them is only in the 4–5 septa and occasionally branched conidiophores, which were not the crucial distinctive features to definite a new species. M. chiuanum was also regarded as a synonym of M. haptotylum by Rubner (1996). Based on the discussion above, we treat it as a synonym of Da. candidum.

(Fig. 3.58)

Dactylellina cionopaga (Drechsler) Ying Yang & Xing Z. Liu, Mycotaxon 97: 158 (2006)
Dactylella cionopaga Drechsler, Mycologia 42: 30 (1950)

Characteristics:

Dactylellina ellipsospora (Preuss) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 110 (1999)
Dactylella ellipsospora (Preuss) Grove, J. Bot. Lond. 24: 200 (1886)
Menispora ellipsospora Preuss in Sturm, Deutschl. Fl. Abt. 3:H.8:T.47 (1848)
Monacrosporium ellipsosporum (Preuss) R.C. Cooke & C.H. Dickinson, Trans. Brit. Mycol. Soc., 48: 623 (1965)

Characteristics:

Dactylellina gephyropaga (Drechsler) Ying Yang & Xing Z. Liu, Mycotaxon 97: 158 (2006)
Dactylella gephyropaga Drechsler, Mycologia 29: 512 (1937)
Arthrobotrys gephyropaga (Drechsler) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Gamsylella gephyropaga (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 110 (1999)
Golovinia gephyropaga (Drechsler) Mekht., Mikol Fitopatol.1: 276 (1967)
Monacrosporium gephyropaga (Drechsler) Subram., [as ‘gephyropagum’] J. Indian bot. Soc.42: 293 (1964) [1963]

Characteristics:

Dactylellina leptospora (Drechsler) M. Morelet, Bull. Soc. Sci. nat. Arch. Toulon & du Var 178: 6 (1968)
Dactylella leptospora Drechsler, Mycologia 29: 507 (1937)
Dactylosporium leptospora (Drechsler) Mekht., Mikol. Fitopatol. 1: 277 (1967)
Monacrosporium leptosporum (Drechsler) A. Rubner, Stud. Mycol. 39: 79 (1996)

Characteristics:

Colonies on CMA whitish, rapidly growing. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, mostly 1.2–3 μm, rarely up to 4 μm wide. Conidiophores hyaline, erect, septate, 75–250 μm long, 2.5–5 μm wide at the base, tapering upwards very slightly, 1–2 μm wide at the apex, mostly simple and bearing a single terminal conidium, but occasionally bearing an additional conidium on a short branch attached to the main axis near its apex. Conidia hyaline, mostly straight, elongate fusoid or cylindrical, 30–92 (64) × 4–6 (4.5) μm, 4–15-septa, after falling off, often giving rise individually to 1 or 2 globose knobs mostly on scarcely modified distal prolongations, more rarely on lateral stalks; often too, producing on slightly branched conidiophores, 50–125 μm long, 2–3 μm wide at the base and 1.3–1.8 μm wide at the apex, secondary conidia mostly 10–35 × 4–5.8 μm, 3–8-septate. Two types of trapping devices were observed in culture: stalked adhesive knobs and non-constricting rings.

Distribution:

China (Beijing, Guizhou, Hubei, Xizang, Yunnan), India, Russian, USA

Material examined:

SJt3.9.68, isolated from field soil in Huaxi, Guizhou in 1996 by Ke-Qin Zhang; XZD-2, XZD-3, isolated from soil in Xizang in August 2000 by Minghe Mo; DL1-1-1, isolated from forest soil in Dali, Yunnan in September 2002 by Jing Zhang; YMF1.00114, isolated from soil in Kunming, Yunnan in 2002 by Lu Cao; J34-1, J34-2, isolated from forest soil in Jianshui, Yunnan in 1999 by Yanju Bi; YMF1.00115, YMF1.00117, YMF1.00042, YMF1.00562, isolated form soil in Dali and Lijiang, Yunnan in September 2002 by Jing Zhang. Permanent slide: STt3.9.68.

Notes:

The fungus is easy to distinguish from other species because of its elongate-fusiform to cylindrical and greater number of conidial septa. Dactylaria dasguptaii and Kafiaddinia fusariispora were treated as synonym of Dactylaria leptospora because of similar trapping devices and conidial characteristics (Rubner, 1996). All the characteristics of examined material matched well with original distribution of Da. leptospora. (Fig. 3.72)

Dactylellina lobata (Dudd.) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Dactylella lobata Dudd., Trans. Br. mycol. Soc. 34 (4): 489 (1951)
Gamsylella lobata (Dudd.), M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 108 (1999)
Monacrosporium lobata (Dudd.) A. Rubner, Stud. Mycol.39: 80 (1996)

Characteristics:

Mycelium septate, occasionally branched, 2–5 µm wide. Conidiophores erect, single, 250 μm high. Conidia fusiform, mainly with 3 septa, 32–54 × 8–12 μm, each at the apex of an erect conidiophore. Trapping nematodes by adhesive unstalked knobs, which sometimes joined together to form loops.

Distribution:

UK.

Notes:

The description is based on the protologue. In this species, knobs often form a string, which resemble adhesive branches of Da. cionopaga, but the adhesive cell of the latter is rectangle. In addition, conidia of the two species are different. (Fig. 3.73)

Dactylellina lysipaga (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 111 (1999)
Dactylella lysipaga Drechsler, Mycologia 29: 503 (1937)
Golovinia lysipaga (Drechsler) Mekht., Mikol. Fitopatol.1: 277 (1967)
Monacrosporium lysipagum (Drechsler) Subram., J. Indian Bot. Soc. 42: 293 (1963)

Characteristics:

Dactylellina multiseptata (H.Y Su & K.Q. Zhang) Z.F. Yu, comb. nov.
Monacrosporium multiseptatum H.Y. Su & K.Q. Zhang. Mycotaxon 92: 193 (2005)
MB 804794

Characteristics:

Colonies on CMA plates growing quickly, attaining 6 cm diameter within 7 days at 25 °C. Mycelium spreading, vegetative hyphae hyaline, septate and branched, mostly 1.8–2.5 µm wide. Conidiophores erect, simple, septate, 170–260 µm long, 2.5–3 µm wide at the base, gradually tapering upwards to a width of 1.7–2 µm at the apex, bearing a single conidium, occasionally two conidia. Conidia hyaline, elongate fusiform to straight clavate, sometimes apparently curved, narrowly round at the distal end, tapering towards the narrow truncate at the base, somewhat constricted at septa, 67.5–132.5 (91.6) × 3.8-17.5 (15.5) µm, 4–9-septate, mainly 6–7- septate. The proportion of conidia with 4, 5, 6, 7, 8 and 9 septa is 1.8, 3.6, 23, 45, 25.1 and 2 % respectively. Chlamydospores sphaerical to ellipsoidal, intercalary, about 5–8 × 4–6 µm. In the presence of nematodes the fungus forms stalked adhesive knobs which are unicellular, subsphaerical. The knobs usually 11 µm long, 10 µm wide, with a stalk of 20–67.5 µm.

Distribution:

China (Yunnan)

Material examined:

YMF1.00127, isolated from soil in Yunnan in 2003 by HongYan Su.

Notes:

Da. multiseptata resembles but distinctly differs from two nematode-trapping fungi, Da. candidum and Da. ellipsospora in conidial shape and type of predacious device. Da. multiseptata produces larger conidia [67.5–132.5 (91.6) × 3.8–17.5 (15.5) µm] and more septa (usually 6–8) than Da. candidum [33–50 (43.7) × 7.4–13.3 (10.7) µm, mainly 4-sepate] and Da. ellipsospora [37.5–62 (48.3) × 8.7–19.3 (13) µm, often with 4 septa]. Additionally, Da. multiseptata does not form denticles on the apex of conidiophores, while Da. candidum and Da. ellipsospora often produce 2–5 short branches near the apex. (Fig. 3.77)

Dactylellina parvicolla (Drechsler) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Dactylella parvicollis Drechsle, Sydowia 15: 13 (1962)
Gamsylella parvicollis (Drechsler) M. Scholler, Sydowia 51: 109 (1999)
Golovinia parvicollis (Drechsler) Mekht., Khishchnye nematofagovye Griby-Gifomitsety: (Baku)162 (1979)
Monacrosporium parvicolla (Drechsler) R.C. Cooke & C.H. Dickinson [as ‘parvicollis’], Trans Br Mycol Soc 48 (4): 622 (1965)

Characteristics:

Mycelium colourless, sterile hyphae branched, septate, 1.5–3.8 μm wide. Conidiophores colourless, erect, mostly 130–290 μm long, 3–4.5 μm wide at the base, tapering gradually upwards, 1.8–2.2 μm wide at the apex bearing a single conidium. Conidia colourless, commonly spindle-shaped, rounded at the distal end, narrowly truncate at the base, 35–45 × 8–14 μm, 2–4- septate, mainly 4-septate. Capturing nematodes by globose or obovoid or prolate ellipsoid stalks adhesive knobs measuring 6.5–11 × 5.5–9 μm.

Distribution:

China (Beijing, Fujian, Hubei, Shandong, Xizang, Yunnan), Ecuador (National Parc Cotopaxi), Germany (Berlin-Dahlem, Berlin), USA (California, Colorado).

Material examined:

YMF1.00028, YMF1.00029, YMF1.00546, isolated from field soil in Wuhan, Hubei in 2001 by Xuefeng Liu; XZM-8, isolated from forest soil in Xizhang in August 2000 by Minghe Mo.

Discussion:

Da. parvicolla can be distinguished from related species of Dactylellina by its 3–5 septate (mostly 4-septate), spindle-shaped conidia. The conidial dimensions of the present isolate is wider than those of the type strain (29–47 × 6–10.5 μm). (Fig. 3.78)

Dactylellina phymatopaga (Drechsler) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1042 (2005)
Dactylella phymatopaga Drechsler, Mycologia 46: 775 (1954)
Gamsylella phymatopaga (Drechsler) M. Scholler, Sydowia 51: 109 (1999)
Golovinia phymatopaga (Drechsler) Mekht., Khishchnye nematofagovye Griby-Gifomitsety (Baku): 165 (1979)
Monacrosporium phymatopagum (Drechsler) Subram.[as ‘phymatophagum’], J. Indian bot. Soc 42: 293 (1963)

Characteristics:

Mycelium scanty; vegetative hyphae hyaline, branched, septate at moderate intervals, 1.8–3.5 μm wide. Conidiophores hyaline, erect, septate, 150–500 μm long, 5–9 μm wide at the base, gradually tapering upwards to a width of 2.5–4.5 μm at the apex, bearing a single conidium, occasionally forming 1–2 short branches near the apex with conidia. Conidia hyaline, spindle-shaped, truncate and rather narrow at the base, rounded at the distal end, 46–71 (62.3) × 21–29 (24.7) μm, 1–5-septate, mostly 3–4-septate. Capturing nematodes by means of unstalked adhesive knobs, which can grow out to form branches.

Distribution:

China (Beijing, Hebei, Jilin, Sichuan, Yunnan), Germany (Berlin Dahlem, Berlin), India, Netherlands (Naaldwijk), Sweden.

Material examined:

N4-1, isolated from forest soil in Jiuzhaigou, Sichuan in April 2003 by Xuefeng Liu; YMF1.1413, isolated from forest soil in Dehong, Yunnan in 2003 by Hong Luo. Permanent slide: N4-1

Notes:

This species closely resembles Da. ellipsospora with its solitary conidia, which are spindle-shaped and 4 septa; however, conidia are much longer in Da. ellipsospora. The trapping devices of Da. phymatopaga are not the typical adhesive knobs like those of Da. ellipsospora, which are obovoid rather than globose and can grow out to form adhesive branches. (Fig. 3.79)

Dactylellina quercus Bin Liu, Xing Z. Liu & W.Y. Zhuang [as ‘querci’], FEMS Microbiol. Lett. 245 (1): [99] (2005)

Characteristics:

Colonies colourless on PDA or CMA, reached to 60–65 mm in diameter on PDA and 45 mm CMA after 20 days culture at 23–25 °C. Aerial mycelium sparse, hyphae hyaline, septate, branched, 2.5–3.5 µm wide. Conidiophores mostly 130–180 µm high, 5–6.5 µm wide at the base, 1.5–2.5 µm at the apex, sometime branched near the apex, bearing a single conidium. Conidia were commonly spindle-shaped, slightly rounded at the distal end, narrowly truncate at the base, 25–32.5–40 (–50) × 8–9.5–12 μm, with 3–5 and mainly 3-septate, but the central cell is not larger than the others. Chlamydospores not observed. Trapping nematodes by means of stalked knobs (0–5.5 μm), knobs produced frequently on the nutritional agar plates even without challenging with nematodes.

Sexual state:

Orbilia querci

Distribution:

China (Beijing, Huairou County)

Notes:

This species resembles Da. drechsleri, Da. ellipsospora and Da. haptotyla in the shape of conidia and adhesive knobs, but differs in that it lacks the largest cell in conidia and in having shorter stalks of adhesive knobs. The sequence divergence of the ITS1 region between Da. quercus and the other knobs forming species tested is 23.8–33.4, which separates Da. quercus from its related species. (Fig. 3.80)

Dactylellina robusta (J.S. McCulloch) Yan Li, in Li, Hyde, Jeewon, Cai, Vijaykrishna & Zhang, Mycologia 97 (5): 1043 (2005)
Monacrosporium robustum J. S. McCulloch, Trans. Br. Mycol. Soc. 68: 177 (1977)
Gamsylella robusta (J.S. McCulloch) M. Scholler, Hagedorn & A. Rubner, Sydowia 51: 109 (1999)

Characteristics:

Colonies on CMA white, slow growing. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched. Conidiophores hyaline, erect, septate, unbranched, 150–450 μm long, 5–8 μm wide at the base and tapering to 3–4 μm wide at the apex, bearing a single conidium. Conidia hyaline, spindle-shaped, 68–85 × 20–30 μm, 3–5-septate. Chlamydospores not observed. Capturing nematodes by means of stout unicellular unstalked adhesive knobs, 16–24 × 9–10 μm.

Distribution:

China (Yunnan), West Australia.

Material examined:

YMF1.1413, isolated from forest soil in Ruili, Yunnan in September 2003 by Hong Luo.

Notes:

Da. robusta resembles Da. phymatopaga (Drechsler) Y. Li (2005), in trapping devices and spore shape, but differs in the larger size of the hyphae, traps and conidia. Da. robusta is easily recognized by its large conidia and its characteristic trapping devices, which just are unicellular adhesive knobs. In Da. phymatopaga, trapping devices can grow out to form adhesive branches. (Fig. 3.81)

Dactylellina sichuanensis Yan Li, K.D. Hyde & K.Q. Zhang, in Li, Jeewon, Hyde, Mo & Zhang, Mycol. Res. 110 (7): 792 (2006)

Characteristics:

Colonies on PDA villiform, whitish, extending to 5 cm diameter at 25 °C, 7 cm diameter at 28℃ and not growing at −4 °C or 35℃ within 7 d. The reverse side of the media is of the same colour. Colonies on CMA whitish, slow-growing, and extending to a diameter of 4 cm at 25 °C, 6 cm 28 °C and not growing at −4 °C or 35 °C within 10 d. Mycelium spreading, scanty, vegetative hyphae hyaline, septate, branched, mostly 2.5–5 µm wide. Conidiophores hyaline, erect, simple, septate, 139–198.5 µm (168.5 µm) high, 2–2.5 µm wide at the base, gradually tapering upwards to a width of 0.5–1 µm at the apex, bearing one single conidium. Conidia 35–82.5 µm (53.5 µm) × 7.5–17.5 µm (13 µm), hyaline, spindle-shaped, straight or sometimes slightly curved, acutely narrowing towards and truncate at the base, the central cell the largest, (3–)4 (–6) septa; proportion of conidia with 3,4,5 and 6 septa are 14, 76, 9 and 1 %, respectively. Two types of trapping devices were observed in culture: stalked adhesive knobs, 20–50 µm long, unicellular, subsphaerical or prolate ellipsoidal; non-constricting rings approximately circular, composed of three subequal arcuate cells. Chlamydospores were not observed in culture.

Distribution:

China (Sichuan)

Notes:

This species is distinct in having two types of trapping devices and larger conidia from similar species within the same genus. Da. sichuanensis is morphologically similar to Da. lysipaga, which also possesses two types of trapping devices, simple conidiophores and spindle-shaped conidia. However, the main differences between these two are the size of the conidia and the number of conidial septa. Da. sichuanensis produces larger conidia than Da. lysipaga. Only 2–4 septa are present in Da. lysipaga whereas Da. sichuanensis is usually characterized by more than four septa. (Fig. 3.82)

Species of the Genus Drechslerella

Drechslerella anchonia (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 99 (1999)
Arthrobotrys dactyloides Drechsler, Mycologia 29 (4): 486 (1937)
Arthrobotrys anchonia Drechsler, Mycologia 46: 762 (1954)
Dactylariopsis dactyloides (Drechsler) Soprunov [as ‘dactyloidea’], Predacious fungi-Hyphomycetes and their use in the control of pathogenic nematodes: 142 (1958)
Nematophagus anchonius (Drechsler)Mekht., Khishchnye Nematofagovye Griby-Gifomitsety, (Baku): 108 (1979)

Drechslerella Subram. emend. M. Scholler, Hagedorn & A. Rubner
Type species: Drechslerella acrochaeta (Drechsler) Subram.–J. Ind. Bot. Soc. 42: 299 (1963)
Dactylella acrochaeta Drechsler—Mycologia 44: 541 (1952)
Dactylariopsis Mekht. 1967
Type species: D. brochopaga (Drechsler) Mekht.—Mikol. Fitopatol. 1: 278 (1967)
Dactylaria brochopaga Drechsler—Mycologia 29: 517, 1937
Golovinia Mekht. 1967
Type species: Golovinia bembicodes (Drechsler) Mekht.—Mikol. Fitopatol.1: 257 (1967)
Dactylella bembicodes Drechsler—Mycologia 29: 491 (1937)

Characteristics:

Mycelium slow-growing. Hyphae septate, branching, hyaline. Conidiophores simple or rarely branched, apex mainly simple without modifications, rarely with short denticles or with geniculate proliferations. Conidia mainly formed singly at the apex of the conidiophores, rarely in clusters. Conidia holoblastic, hyaline, one to four septate, mainly ellipsoidal, obovoidal, spindle-shaped, or top-shaped, rarely clavate, or cylindrical. Microconidia and microconidiophores rarely observed. Chlamydospores, when present, intercalary and in chains, thick-walled, sphaerical to ovoid, yellow pigmented. Sexual state, when known, belonging to the genus Orbilia Fr. (Helotiales). Trapping nematodes by means of spontaneously formed three-celled, stalked, constricting rings; saprotrophic capacities weak.

Key to Species of Drechslerella

1. Conidiophores usually with swollen tips and denticles, bearing apical clusters of conidia 2

1. Tips of conidiophores bearing a single conidium, occasionally with very short subapical lateral branches 5

2. Conidia elongate-obovoid, mostly 1-septate, occasionally 2-septate D. anchonia

2. Conidia other types 3

3. Conidia digitiform 4

3. Conidia elongated-ellipsoid, 0–1-septate, mostly 1-septate D. yunnanensis

4. Conidia cylindrical to clavate, mostly 3-septate D. brochopaga

4. With two types of conidia, macroconidia clavate, 1-septate D. dactyloides

5 Conidiophores of the genicularioid type, conidia ellipsoid D. effusa

5. Conidiophores unbranched or occasionally with subapical lateral branches 6

6. Conidia ellipsoid or broadly obovoid 7

6. Conidia spindle-shaped 9

7. Conidia broadly obovoid, with 1-septate at the base D. polybrochum

7. Conidia ellipsoid or wide digitiform 8

8. Having two types of conidia, macroconidia ellipsoid, 2-septate D. heterospora

8. Conidia ellipsoid or wide digitiform, straight or curved, 1–3-septate

D. stenobrocha

9. Conidia 2-septate 10

9. Septa of conidia more than 2 septa 11

10. Conidia 26.5–45 × 14–18.5 μm, bearing an appendage at conidia distal apex D. acrochaetum

10. Conidia 25–52.5 (33.2) × 12.5–29 (17.3) μm, conidiophores with globose apex

D. doedycoides

11. Conidia mostly 3-septate 12

11. Conidia mostly 4-septate 13

12. Conidia narrower, 42.5–62.5 (47) × 15–22.5 (16.9) D. inquisitor

12. Conidia 2–4-septate, mostly 3-septate, 40–57.5 (51) × 15.5–35 (24.6)

D. aphrobrocha

13. Conidia 36–43.2 (40) × 16.8–21.6 (20.5) D. bembicodes

13. Conidia 2–5-septate, 45.6–55.2 (49.5) × 16.8–21.6 (19.8) D. coelobrochum

Accepted Species of Drechslerella

Drechslerella acrochaeta (Drechsler) Subram., J. Indian Bot. Soc. 42: 299 (1964) [1963]
Dactylella acrochaeta Drechsler, Mycologia 44 (4): 541 (1952)
Golovinia acrochaeta (Drechsler) Mekht., Khishchnye Nematofagovye Griby—Gifomitsety (Baku): 138 (1979)
Monacrosporium acrochaetum (Drechsler) R.C. Cooke, Trans. Br. Mycol. Soc. 50 (2): 317 (1967)

Characteristics:

Colonies on CMA rather slow growing and attaining a diameter of 1 cm within one week at 25 °C. Hyphae hyaline, septate, branched. Conidiophores hyaline, erect, septate, simple, 110–320 μm long, 2–4 μm wide, bearing a single conidium at the apex. Conidia hyaline, broadly spindle-shaped, rounded at the distal end and truncate at the base, 1–2-septate, 26.5–45 × 14–18.5 μm, bearing distally an appendage approximate alignment with the spore axis. Trapping nematodes by means of constricting rings.

Distribution:

China (Guizhou, Hebei, Jilin, Yunnan), USA

Material examined:

95X9–1, isolated from forest soil in Xishuangbanna Yunnan in June 1994 by Xingzhong Liu.

Notes:

The conidial appendage was observed in culture in our isolate. Conidia shape, septa and size of examined material matched well with original description (Drechsler 1952). (Fig. 3.83)

Drechslerella polybrocha (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 100 (1999)
Dactylella polybrocha (Drechsler) Mekht., [as‘ polybrochum ’]Dokl. Akad. Nauk Aerb. SSR, 20: 70 (1964)
Golovinia polybrocha (Drechsler) Mekht., Khishchnye, Nematofagovye Griby Gifomitsety, 137 (1979)
Monacrosporium polybrochum (Drechsler) Subram., Kavaka 5: 96 (1977)[1978]
Orbilia tenebricosa (Svrček) Baral, in Yu, Zhang, Qiao, Baral, Weber & Zhang, Mycotaxon 96: 167 (2006)
Patinella tenebricosa Svrček, česká Mykol. 31 (3): 135 (1977)
Trichothecium polybrochum Drechsler, Mycologia 29 (4): 536 (1937)

Characteristics:

Mycelium spreading, vegetative hyphae hyaline, septate, 2 to 4.5 μm wide; conidiophores hyaline, septate, erect, 275–400 μm long, 7 μm wide at the base, gradually tapering upwards to a width of 3 μm at the apex, bearing one single conidium. Conidia hyaline, broadly obovoid, 35 × 24 μm, divided by a single septum into a small obconical basal cell about 6.5 μm long, and a much larger distal cell, about 28.5 μm long, often enveloped in a hyaline layer of mucus 2 to 3 μm thick. Capturing nematodes by means of constricting rings.

Distribution:

USA

Notes:

The description is based on the protologue. This species differs from other species in having 1 septate, broadly obovoid conidia, which is often enveloped in a hyaline layer of mucus when attached on conidiophores. (Fig. 3.94)

Drechslerella stenobrocha (Drechsler) M. Scholler, Hagedorn & A. Rubner, Sydowia 51 (1): 100 (1999)
Dactylella stenobrocha Drechsler, Mycologia 42: 10 (1950)

Characteristics:

Mycelium scanty; vegetative hyphae hyaline, septate, branched 1.7–3.7 μm wide. Conidiophores hyaline, erect, 425–550 μm long, 4.5–6.5 μm wide at the base, gradually tapering upwards to a width of 2.5–3 μm at the apex, bearing a single conidium. Conidia hyaline, elongate ellipsoidal or broadly finger-shaped or sometimes slightly clavate, straight or slightly curved, somewhat rounded to truncate at the narrowed base, broadly rounded at the apex, 34–56.5 × 12.5–16.5 μm, 1–3-septate. Chlamydospores not present. Capturing nematodes by means of constricting rings.

Distribution:

China (Hebei), USA (Wyoming)

Notes:

The description is based on the protologue. This species can be distinguished from other species of Drechslerella by its ellipsoid or wide digitiform conidia. (Fig. 3.95)

Drechslerella yunnanensis Z.F. Yu & K.Q. Zhang, Mycotaxon 110: 254 (2009)

Characteristics:

Colonies white, growing slowly on CMA medium, attaining less than 25 mm diam. in 10 days at 25 °C. Vegetative hyphae hyaline, septate, 3.5–4 μm wide, aerial mycelium sparse, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores hyaline, septate, erect, unbranched or occasionally branched below, 60–100 (–220) μm, 3.8–4.2 μm wide at the base, tapering gradually upwards to 1.5–2 μm near the apex, with 2–7 (–10) denticles of 2.3–4.2 μm long, each bearing one conidium in a capitate or racemose arrangement. Conidia hyaline, straight, elongate ellipsoidal, rounded at the apex, with a small truncate protuberance at the base, 7.8–12.9 (–17.8) × 3.3–4.2 μm, (0–)1-septate, proportion of aseptate conidia 17 %. Nematodes are captured by three-celled constricting rings. In the non-constricted state, the outer diameter is 18–21.9 µm, the inner diameter is 12–13.6 µm.

Sexual state:

Orbilia cf. orientalis.

Distribution:

China (Yunnan)

Material examined:

YMF1.01863, isolated from Orbilia cf. orientalis, collected in Yimen, Yunnan in August 2006 by Z. F. Yu.

Notes:

Within species of Drechslerella where conidia are arranged in a cluster at the apex of conidiophores, Dr. yunnanensis can be distinguished from the other three species by the size and shape of conidia. Details are as follows: Dr. brochopaga has much larger conidia (26–46 × 5–9 µm) with more (mainly 3) septa (Drechsler 1937), Dr. anchonia has obovoid, much larger conidia 29–43 (–35) × 15–19 (–16.8) µm with a single septum in the lower third (Drechsler 1954). Conidia of Dr. dactyloides are narrowly ellipsoidal or somewhat digitiform, often very slightly curved, and there are more conidia in the apex of conidiophores and conidia are much larger 32–48 × 7–9.5 μm (Drechsler 1937). (Fig. 3.96)

Asexual State-Sexual State Connections of Nematode-Trapping Fungi

Fungi are classified primarily based on the structures associated with sexual reproduction, which tend to be evolutionarily conserved. However, many taxa reproduce only asexually, which cannot easily be placed in a classification based on sexual characters, while some produce both asexual and sexual states. The International Code of Botanical Nomenclature (Vienna Code) (McNeill et al., 2006) previously permitted mycologists to give asexually reproducing fungi (asexual states) separate names from their sexual states (sexual states). When names are available for both the asexual and sexual states of the same taxon, the holomorph usually took the sexual state name. However, where several asexual states were associated with the same sexual morph, this nomenclature could not be followed. Although dual nomenclature has persisted for decades, the concept of permitting separate names for asexual states of fungi with a pleomorphic life-cycle has been an issue of debate since the phenomenon was first recognized in the mid-19th century. More recently, it was deemed that one fungus can only have one name and this is now being put into practice (Taylor, 2011). After 1 January 2013, one taxon can only have one name, the system of permitting separate names to be used for sexual and asexual states is no longer permissible (Hawksworth, 2011). The topic presented here focuses only on the asexual—sexual state connections, but not with name validity, as the latter is still being debated.

Drechsler (1937) was possibly the first to report an asexual state connected to a sexual state in nematode-trapping fungi. He obtained apothecia of an Orbilia-like species in a contaminated culture of Arthrobotrys superba when challenged with nematodes. The apothecia were flesh-coloured, 0.5-0.8 μm diameter, somewhat stalked and with a prominent marginal border and the cylindrical asci were 29-32 × 3 μm. Ascospores were 5 × 1.3 μm, hyaline and tear-shaped. This sexual state was similar to Orbilia fimicola Jeng & Krug in morphology. Zachariah (1983) obtained Orbilia-like apothecia when crossing an auxotrophic strain (D30A) of Drechslerella dactyloides with a prototrophic strain (D31P). However, the apothecia were sterile; no asci were formed. Since that time, at least 14 nematode-trapping asexual species have had credible connections established with Orbilia species and one with Patinella tenebricosa (Table 3.1). In the following, detailed descriptions of 12 asexual nematode-trapping fungi states connected to a sexual state are presented and most illustrated. Two of the connections identified by Pfister (1997), i.e. Drechslerella doedycoides—Orbilaria sp., and Drechslerella polybrochum—Patinella tenebricosa, lack taxonomic descriptions.

Table 3.1 Asexual nematode-trapping fungi in Orbiliaceae connected to a sexual state

Full size table

Arthrobotrys oligospora Fresen. var. oligospora
Sexual morph: Orbilia auricolor (A. Bloxam ex Berk.) Sacc.
Reference: Pfister and Liftik (1995)

Arthrobotrys cladodes Drechsler var. macroides Drechsler
Sexual morph: Orbilia auricolor (A. Bloxam ex Berk.) Sacc.
Reference: Pfister and Liftik (1995)

Asexual morph (Culture No. 90): Cultures of germinated ascospores on MEYE (Lilly and Barnett, 1951), white, becoming pale tan, forming hyphal strands on the surface and cottony patches, remaining white. On CMA growth sparse, remaining white. Conidiophores erect, branching, not proliferating; each branch terminating in a loose whorl of conidia. Conidia blastic, hologenous, 18–20 × 6–8 μm, elongate-ellipsoid, with a single septum, the cells nearly equal, without constrictions at the septa. Conidia basipetally produced at several closely spaced loci on a sometimes inflated, often distorted, terminal area of the conidiogenous cell; secession schizolytic, leaving a slight protuberant, unthickened, open denticle with a slight frill. Conidiogenous cell determinant, persistent. Cultures induced by nematodes (Cephalobus sp.) normally producing adhesive networks within 12 h.

Sexual morph (Specimen No. 90): Ascomatal specimens were collected by Pfister and Liftik in July, 1994, on decorticated wood from a swampy area, Purgatory, Tract, Westwood, Massachusetts. Ascomata up to 1 mm diameter, yellow to orange, pulvinate to turbinate; asci 8-spored, 30–40 × 3–4 μm, cylindric, J-, tapered towards the base and often forked, at the apex truncate without an obvious pore; ascospores curved, narrowly clavate, broad and rounded at one end, narrowing to an acute point at the other end, non-septate containing a single inclusion which stains intensely in cresyl blue, 8–12.5 × 0.9–1.5 μm; paraphyses branching below, abruptly swelling to become capitate above reaching a diameter of 3-3.5 μm; excipulum of angular cells.

Arthrobotrys cystosporia
Sexual morph: Orbilia auricolor (A. Bloxam ex Berk.) Sacc.

Asexual morph (Culture No. SBP88, Fig. 3.97): Colonies colourless, spreading on CMA, reaching 5 cm at 25 °C after 10 days. Vegetative hyphae hyaline, septate, 3.2–5.4 μm wide. Aerial mycelium sparse. Conidiophores hyaline, erect, simple, septate, 60–200 μm high, 2.5–5.5 μm wide at the base, gradually tapering upwards to a width of 1.8–2.5 μm at the apex. Conidia produced at the apex, sometimes in a cluster of 2–5 conidia. Primary conidia hyaline, broadly clavate or broadly turbinate to obovoid, 26–38.5 (31.4) × 13–22 (20) μm, with 2–3 septa. The second conidiophores from the primary conidia colourless, erect, simple, septate, 35–140 μm high, 2–4.5 μm wide at the base and 1.8–2.5 μm at the apex, producing 3–7 secondary conidia on conspicuous denticles loci at near the apex of conidiophores. The secondary conidia hyaline, elongate ellipsoid-cylindrical or slightly clavate, broadly rounded at the apex, rounded truncate at the narrowed base, 26–38.5 (31.4) × 13–22 (20) μm, 0–1-septate. Chlamydospores ellipsoidal. Trapping nematodes by three-dimensional adhesive networks. (Fig. 3.97)

Sexual morph (Specimen No. SBP88, Fig. 3.98): Soils samples were collected from Binchuan County, Yunnan, China on March 21, 2008 by HongYan Su. Subsamples of 2–5 g were spread on CMA plates and stored at 28ºC. After incubation for 10 days, apothecia of an Orbilia sp. were observed on the soil granules, and later also on other areas of the plates. Apothecia superficial, sessile, pale cream. Disc 0.4–0.9 mm diameter, smooth, plane, margin even. Ectal excipulum composed from base to margin of globose or subglobose cells, 5–12 μm diameter, with thin or slightly thickened walls. Asci cylindric-clavate, tapered and often forked at the base, apex rounded or truncate-rounded, 8-spored, 35.5–39 (37) × 3.5–4.7 (4.1) μm in living state. Ascospores banana-shaped or narrowly clavate, medium curved, one end narrower, broadest above and slightly trapped to the rounded at proximal end, non-septate, containing an elongate tear-shaped spore body at the broader end, 7.5–11 (8.6) × 0.9–1.2 μm. Paraphyses hyaline, cylindric-clavate, often branched below, septate in the lower part, 1.4–1.8 (1.6) μm diameter, slightly expanded to 2.3–3 μm at the apex, which is not encrusted. (Fig. 3.98)

Asexual morph (Culture Nos. 45 and 55): Cultures of germinated ascospores on MEYE at first white, becoming rose within 1 wk, growth partially cottony with hyphal strands forming across the surface of the medium. On CMA growth is uniform but sparse, remaining white. Conidiophores erect, with whorls of conidia. Conidia blastic, hologenous, 14–28 × 10–14 μm, obovoid, 1-septate, often constricted at the septum, the proximal cell smaller than the distal cell. Conidia basipetally produced, at several closely spaced loci, on somewhat inflated areas of the conidiogenous cell; secession is schizolytic, leaving protuberant, open, unthickened denticles with frills. Conidiogenous cell are indeterminate, persistent, with hologenous sympodial, presumptive proliferation. Cultures with nematodes (Cephalobus sp.) produced the trap device of adhesive networks within 12 h.

Sexual morph (Specimen Nos. 45 and 55): Ascomatal specimens were obtained from a crustose lichen on a rock which had been incubated in a moist chamber. Taxonomic characteristics of specimen Nos. 45 and 55 were similar as that of specimen No. 90 according to description of Pfister and Liftik (1995).

Arthrobotrys vermicola (R.C. Cooke & Satchuth.) Rifai
Sexual morph: Orbilia blumenaviensis (Henn.) Baral & E. Weber
Reference: Qiao et al. (2012)

Arthrobotrys psychrophilum
Sexual morph: Orbilia auricolor (A. Bloxam ex Berk.) Sacc.
Reference: Rubner (1996)

Asexual morph (Culture Nos. CBS 319.94): The strain was isolated form soil collected from Ecuador (Province Cotopaxi, north of Latacunga, hacienda “La Cienega”). Cultures grew well on CMA medium. Macroconidia were formed after one week on mostly geniculate conidiophores, microconidia appeared later, especially from germinating macroconidia (and also on the fruit bodies). Conidiophores of macroconidia simple, 250–310 μm high, bearing up to 6 conidia. Macroconidia spindle-shaped and mostly 3-septate, with a ratio of length to width of 2.48, 47–52–59.5 × 17.5–21–22.5 μm. Microconidia ellipsoidal to obovoidal and mostly 1-septate, 15-18-22 × 5-6.5-7.5 μm. Chlamydospores in chains, thick-walled, smooth and yellow. When adding the nematode species Turbatrix aceti, the fungus produced adhesive networks.

Sexual morph (Specimen No. A.R.9312): Culture of CBS 319.94 on CMA medium amended with oat husks produced apothecia after two months. Mature apothecia deviating from normal Orbilia apothecia by strongly convex warted hymenia. Asci 45–58 × 3.5–4.2 μm, ascospores 7.5–13 × 1–1.3 μm. An ellipsoid refractive spore body is attached to the spore apex by a thin thread and 3–5 of the lower spores are inversely oriented within asci. Paraphyses slightly inflated at apex. Cortical cells of ectal excipulum terminated by 2–6 μm high glassy caps.

Arthrobotrys superba Corda
Sexual morph: Orbilia fimicola Jeng & Krug.
Reference: Pfister (1994)

Deer dung was collected from Berkshire County in western Massachusetts and was placed in a moist chamber. After 2¹/₂ mouths at room temperature and in natural light, the ascomata discovered on dung was used to project ascospores and obtain the asexual state culture. Pfister (1994) confirmed that taxonomic morphology of the sexual state agreed with the original description of Orbilia fimicola (Jeng and Krug, 1977) and he identified the asexual state as Arthrobotrys superba (Drechsler, 1937), but morphological details on both sexual state and asexual state had not been described.

Arthrobotrys yunnanensis M.H. Mo & K.Q. Zhang
Sexual morph: Orbilia auricolor (A. Bloxam ex Berk.) Sacc.
Reference: Mo et al. (2005)

Asexual morph (Culture No. YMF1.00593, HT1.00593, Fig. 3.99): Colony derived from single ascospore, whitish and slow growing on CMA. Mycelium spreading, scanty; vegetative hyphae hyaline, septate, branched, except for occasional storage filaments that densely filled with protoplasm and up to 11 μm wide measuring mostly 2–7 μm in diameter. Conidiophores hyaline, erect, septate, more or less branched, 68–236 μm long, 2.5–5 μm wide at the base, tapering gradually upwards to a width of 2–3 μm below the irregularly expanded, globose or somewhat coralloid apex whereon are borne 10–20 conidia in usually dense capitate arrangement. Conidia hyaline, ellipsoid or elongate obovoid, mostly 10–20 (17.5) × 5–8 (6.2) μm, 1–septate approximately near in the centre of the spore. Chlamydospores not present. Cultures on CMA produce adhesive networks when nematodes were added (Panagrellus redivivus). (Fig. 3.99)

Sexual morph (Specimen No. Mo MH O 002, Fig. 3.100): Wet soil samples were from Mt Xiaobailong, Yiliang, Yunnan, China collected by MingHe Mo on 15 August 2003. Subsamples of 2–5 g were spread on CMA plates and stored at room temperature (about 20–28ºC). After incubation for 20 days, apothecia were observed on the soil granules, and later also on other areas of the plates. Apothecia superficial, sessile, pale cream. Disc 0.3–0.8 mm diameter, smooth, plane, margin even. Ectal excipulum composed from base to margin of globose or subglobose cells, 6–12 μm diameter, with thin or slightly thickened walls. Asci cylindric-clavate, tapered and often forked at the base, apex rounded or truncate-rounded, 8-spored, 30–45 × 3.5–5 μm in living state. Ascospores banana-shaped or narrowly clavate, medium curved, one end narrower, broadest above and slightly trapped to the rounded proximal end, non-septate, containing an elongate tear-shaped spore body at the broader end, 9 × 1.4 μm when shooting from asci and still in living state. Paraphyses hyaline, cylindric-clavate, often branched below, septate in the lower part, 1.5–2 μm diameter, slightly expanded to 2.5–3.5 μm at the apex, not encrusted at apex. (Fig. 3.100)

Arthrobotrys nonseptata Z.F. Yu, S.F. Li & K.Q. Zhang
Sexual morph: Orbilia sp.
Reference: Li et al. (2009)

Asexual morph (Culture No. YMFT 1.01852, Fig. 3.101): Cultures were derived ascospores. Colonies slow-growing on CMA medium, attaining less than 35 mm diameter in 10 days at 25 °C. Vegetative hyphae hyaline, septate, 3.5–4 μm wide, aerial mycelium sparse, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores erect, septate, unbranched, 40–120 μm high, 2–4 μm wide in the lower part, 1.5–2 μm wide at the apex, producing 3–10 conidia from retrogressive conidiogenous loci on conspicuous denticles at and near the apex. Conidia hyaline, non-septate, 11–16.8 × 5–6.6 μm, elongate ellipsoid, constricted at the base by forming a small truncate protuberance. Cultures on CMA produce adhesive networks when nematodes added (Panagrellus redivivus). (Fig. 3.101)

Sexual morph (Specimen No. YMFT 1.01852, Fig. 3.102): Fresh fruit bodies were collected by Y. Zhang on 18 August 2006 from decaying bark of a broad-leaved tree in forest dominated by Cyclobalanopsis glaucoides Schottky and Pinus armandii Franch., in Dalongkou Park of Yimen County, Yunnan Province, China. The authors confirmed that their specimen belongs to an unidentified species of the genus Orbilia and presented a morphological plate, but did not provide a taxonomic description. (Fig. 3.102)

Asexual morph (Culture No. YMF 1.03002, Fig. 3.103): Colonies growing rapidly on CMA medium, attaining 40 mm diameter in 6 days at 28 °C. Mycelium spreading, vegetative hyphae hyaline, septate and branched, mostly 3–6 μm wide. Conidiophores colourless, produced on the mycelium growing at the fringe of the plate, appressed or erect, branched, septate; 150–300 μm high when erect, often 700–1,500 μm when appressed, 4–8 μm wide at the base and 3.5–5 μm at the apex, often recommencing growth after the first group of conidia had been produced and a second head is then formed about 100 μm above the first. This process was repeated until 3–4 (–7) whorls of conidia were produced on a single conidiophore, each group with 2–8 conidia. Two types of colourless conidia were simultaneously formed which mainly differ in their length-width ratio but also in the number of septa: Type a with 1-septate, pear-shaped to obovoid, sometimes elongate ellipsoidal conidia being broadly rounded at the apex, rounded-truncate at the narrowed base, sometimes slightly gradually attenuated at the proximal end, (16.4–)20.4–28.2 × (9.8–)13.5–15.3 (–19) μm; Type b with 1–2 septa, elongate cylindric-clavate, obconical conidia being broadly rounded at the apex, (21.7–)30–34.5 (–39.2) × 12.7–14 μm. The proportion of conidial types a and b was 88 and 12 % respectively. Nematodes are trapped by three-dimensional adhesive networks. (Fig. 3.103)

Sexual morph (Specimen No. YMFT 1.03002, Fig. 3.104): Specimen was collected on decaying angiosperm wood fallen on the ground of a broad-leaved subtropical evergreen forest located in Xiushan Forest Park of Tonghai County, Yunnan Province, China, in July 2007, by S.F. Li and J.W. Guo. Apothecia 0.7–1.5 mm in diameter, superficial, with a distinct stalk up to 0.2–0.3 mm high, scattered to gregarious on decayed wood, smooth, margin even, yellow and translucent throughout when moist, pale brown when dry. Ectal excipulum composed of globose or subglobose cells, near base 20–43 × 15–38 μm, on flanks 15–30 × 12–25 μm. Asci cylindric-clavate, often forked at the base, apex medium truncate (rounded in side view), 8-spored, 28–39 (–45) × 2.6–3.7 (–4.4) μm in dead state. Ascospores falcate, medium to strongly curved, lower end distinctly narrowed, upper end only slightly so, non-septate, containing a spore body at the broader end, with 1–2 minute lipid bodies in the centre, (6.2–)8–11 (–12) × 1–1.2 μm when shot from asci and still in living state. Spore body rounded or elongate ellipsoid, 0.9–1.6 × 0.7–0.8 μm (1.5–2.5 μm including invisible connecting part). Paraphyses hyaline, cylindrical, with distinctly widened, lanceolate apex, septate below, 1.7–2.8 μm wide at widest point, not encrusted. (Fig. 3.104)

Dactylellina parvicolla
Sexual morph: Orbilia cunninghamii
Reference: Liu et al. (2002)

Asexual morph: Colonies reached to 25 mm in diameter on PDA after 10 days. Conidia sparse on the nutritionally rich media, spindle-shaped at maturity, 27.5–37.5 × 8–10 μm, mainly with 3–4 septa. Trapping nematodes by means of sessile knobs, occasionally the knob with a short stalk.

Sexual morph: Specimen was collected from Huai-rou County, Beijing, China on rotten wood of Quercus sp.. Apothecia 0.2–0.5 in diameter, asci 20–25 × 3–4 μm, subcylindrical to clavate, tapered and bifurcate at the base, ascospores 5–6 × 1–1.5 μm, rod-shaped to clavate.

Drechslerella brochopaga (Drechsler) M. Scholler, Hagedorn & A. Rubner
Sexual morph: Orbilia orientalis (Raitv.) Baral
Reference: Yu et al. (2006)

Dactylellina quercus Bin Liu, Xing Z. Liu & W.Y. Zhuang
Sexual morph: Orbilia quercus Bin Liu, Xing Z. Liu & W.Y. Zhuang
Reference: Liu et al. (2005)

Asexual morph (Culture No. AS 3.6762, Fig. 3.105): Colonies colourless on PDA or CMA, reached to 60–65 mm in diameter on PDA and 45 mm on CMA after 20 days culture at 23–25°C. Aerial mycelium sparse, hyphae hyaline, septate, branched, 2.5–3.5 μm wide. Conidiophores mostly 130–180 μm high, 5–6.5 μm wide at the base, 1.5–2.5 μm at the apex, sometime branched near the apex, bearing a single conidium. Conidia were commonly spindle-shaped, slightly rounded at the distal end narrowly truncate at the base, 25–50 × 8–12 μm, with 3–5 and mainly 3-septa, but the central cell is not much larger than the others. Chlamydospores not observed. Trapping nematodes by means of stalked knobs (0–5.5 μm), knobs sphaerical to subsphaerical, 8–12 × 7.5–10 μm. Knobs produced frequently on the nutritional agar plates even without challenging with nematodes. (Fig. 3.105)

Sexual morph (Specimen No. HMAS 88781, Fig. 3.106): Specimen was collected from Labagoumen Forest Park of Huai-rou County, Beijing, China in July, 2002. Apothecia superficial on rotten wood, gregarious, sessile, 0.2–0.5 mm in diameter. Disc concave, smooth, translucent, whitish to pale yellow when fresh, brownish-yellow when dried. Ectal excipulum of textura angularis, 78–96 μm thick, cells isodiametric, 6–10 (–14) μm in diameter. Medullary excipulum of textura intricata, 27–35 μm thick. Subhymenium poorly developed. Asci cylindrical-clavate, narrower and tapered towards the base, sometime forked at the base, apex truncate to rounded, 18–30 × 2.5–3 μm. Ascospores hyaline, subcylindrical to cylindrical-clavate, straight or sometimes slightly curved, non-septate, usually overlapping tightly and biseriate within ascus, 5–6 × 0.8–1.2 μm in water, spore body (SB) tear-shaped to short rod-shaped, 1.1–1.8 × 0.7–1 μm. Paraphyses filiform with a clavate to capitate apex, hyaline, 18–22 μm long, 2–2.5 μm wide at apex and 1.5–2 μm wide below. (Fig. 3.106)

Asexual morph (Culture No. YMF1.01829, Fig. 3.107): Cultures were derived from ascospores. Colonies colourless, spreading on CMA, reaching 48 mm after 14 days at 25 °C. Vegetative hyphae hyaline, septate, 3.5–4 μm wide. Aerial mycelium sparse, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores hyaline, erect, septate, mostly 380–430 μm high, 3.5–4 μm at the base, tapering upwards to a width of 2–2.5 μm at the apex, there bearing short blunt denticles 2–10 μm in length, whereon bearing 3–10 conidia in radiating capitate arrangement, occasionally producing up to 13 conidia in more scattered, irregularly racemose arrangement. Conidia commonly cylindric-oblong, rounded at the distal end, shortly tapered at the somewhat truncate base, 20–36 × 5–7.5 μm, slightly to medium curved especially near distal end, with 1–3 septa, predominantly 3-septate, then terminal cells often exceeding the length of the central cells by a third or even a half. Cultures on CMA produce constricting rings adhesive networks when challenged with nematodes (Panagrellus redivivus). (Fig. 3.107)

Sexual morph (Specimen No. YMFT1. 01829, Fig. 3.108): Specimens were collected on decaying bark of broadleaved tree in a forest at 848 m altitude, located in Jinggangshan Park of Jian City, Jiangxi Province, China, in October 2005 by Y. Zhang. Apothecia 0.8–1.2 mm in diameter, superficial, with a distinct stalk up to 0.2–0.3 mm high, scattered to gregarious on decayed bark, white and translucent throughout when moist, pale brown when dry. Disc slightly concave to flat, margin even and smooth. Ectal excipulum of angular or globose cells, 8–13.8 μm in diameter, with thin or only slightly thickened walls, towards margin of textura prismatica-angularis oriented at a high angle, marginal cells tipped by glassy processes up to 30–40 × 3.5–4.5 μm, curved outwards, agglutinated to form rounded teeth. Medullary excipulum rather thick, of texture globulosa (-prismatica) with intermingled hyphae, subhymenium poorly developed. Asci 29.5–38 × 3.2–4.5 μm, 8-spored, lower (2)3–5 (6) spores inversely oriented (with spore body towards ascus base), cylindric, rounded or truncate at the apex (depending on side of view), tapered and often forked at the base (L, hor H-shaped). Ascospores hyaline, non-septate, cylindric- ellipsoid, sometimes slightly tapered at lower end, 3–4 × 1.6–1.8 μm, with a refractive rod-shaped spore body (SB) at upper end in living mature ascospores, 1.2–1.4 × 0.3–0.5 μm in diameter. Paraphyses 1.3–2 μm wide, enlarged to 2.8–3.7 μm in diameter at the medium to rather strongly clavate or capitate apex, terminal cell much longer than lower cells, apex covered by a rough thin layer of exudates. (Fig. 3.108)

Drechslerella yunnanensis Z.F. Yu & K.Q. Zhang
Orbilia cf. orientalis (Raitv.) Baral.
Reference: Yu et al. (2009)

Asexual morph (Culture No. YMF1.01863, Fig. 3.109): Cultures were derived from ascospores. Colonies white, slow-growing on CMA medium, attaining less than 25 mm diameter in 10 days at 25 °C. Vegetative hyphae hyaline, septate, 3.5–4 μm wide, aerial mycelium sparse, hyaline, septate, branched, 2.5–4 μm wide. Conidiophores hyaline, septate, erect, unbranched or occasionally branched below, 60–100 (–220) μm, 3.8–4.2 μm wide at the base, tapering gradually upwards to 1.5–2 μm near the apex, with 2–7 (–10) denticles 2.3–4.2 μm long, each bearing one conidium in a capitate or racemose arrangement. Conidia hyaline, straight, elongate ellipsoidal, rounded at the apex, with a small truncate protuberance at the base, 7.8–12.9 (–17.8) × 3.3–4.2 μm, (0-)1 septate, proportion of aseptate conidia 17 %. Cultures on CMA produce the trap device of constricting rings when induced by nematodes (Panagrellus redivivus). (Fig. 3.109)

The sexual morph (specimen No. YMFT 1.01863, Fig. 3.110) was collected as fresh fruit bodies by ZeFen Yu in August 2006 from decaying bark of a broad-leaved tree, in Dalongkou Park of Yimen County, Yunnan Province, China (N24°34, E101º00´, alt. 1580 m, coniferous-broadleaf forest dominated by Cyclobalanopsis glaucoides Schottky. and Pinus armandii Franch.). The sexual state is very similar to Orbilia orientalis in having cylindric-ellipsoid ascospores with a refractive, rod-shaped, laterally arranged spore body (SB) at the upper end. Also spore size is very close (protologue of O. orientalis: 3–4 × 1.5–2 µm, the specimen YMFT1.01863: 4.0–4.2 × 1.6–1.9 μm). The apothecial margin is only minutely crenulate and hardly bears any glassy processes, while in the O. orientalis type, the glassy processes are long and agglutinated, forming distinct teeth at the margin. (Fig. 3.110)

Conclusion

In the classification of nematode-trapping fungi, trapping devices are generally more informative than the morphologies of the conidia (shape, number and size of cells) and conidiophores (branching, modification of the apex). The latter characters were previously used in delimiting genera. We conclude that all orbiliaceous nematode-trapping fungi should be placed in the genera of Arthrobotrys, Dactylellina and Drechslerella based on their trap types. Arthrobotrys includes species producing adhesive networks, Dactylellina contain species forming stalked adhesive knobs, unstalked adhesive knobs, or non-constricting rings, while Drechslerella includes species producing constricting rings. Species lacking trap formation, especially members of the genus Dactylella, are excluded from the nematode-trapping fungi, although some share similar morphologies to species of Dactylellina.

A total of 96 species of orbiliaceous nematode-trapping fungi are described and illustrated in detailed, with 54 species from Arthrobotrys, 28 from Dactylellina and 14 from Drechslerella. Nematode-trapping fungi have been found in all parts of the world and in all climatic zones. Most of the nematode-trapping fungi annotated here were isolated from agricultural soils and forest soils, while some of them also inhabit freshwater. The majority of nematode-trapping fungi are fairly ubiquitous, with few species restricted geographically. Species forming adhesive networks are the dominant group.

Fourteen connections have been established between asexual nematode-trapping fungi and their orbiliaceous sexual state. Five asexual species are associated with Orbilia auricolor suggesting that O. auricolor is a species complex. It is difficult to distinguish between members of this complex based only morphological characters of the sexual state. Beside the morphological features, more molecular information, such as gene sequences of ITS, 28S rDNA, 5.8S rDNA and ß-tubulin, should be taken into account in the taxonomy of Orbilia.

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Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, 650091, Kunming, Yunnan, China
ZeFen Yu, MingHe Mo, Ying Zhang & Ke-Qin Zhang

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ZeFen Yu
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Ying Zhang
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Ke-Qin Zhang
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Lab. Conservation Utiliz. Bio-Resour., Yunnan University, Kunming, Yunnan, China
Ke-Qin Zhang
School of Science, Mae Fah Luang University, Chiang Rai, Thailand
Kevin D. Hyde

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Yu, Z., Mo, M., Zhang, Y., Zhang, KQ. (2014). Taxonomy of Nematode-Trapping Fungi from Orbiliaceae, Ascomycota. In: Zhang, KQ., Hyde, K. (eds) Nematode-Trapping Fungi. Fungal Diversity Research Series, vol 23. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-8730-7_3

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DOI: https://doi.org/10.1007/978-94-017-8730-7_3
Published: 23 April 2014
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Taxonomy of Nematode-Trapping Fungi from Orbiliaceae, Ascomycota

Abstract

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Generic names in the Orbiliaceae (Orbiliomycetes) and recommendations on which names should be protected or suppressed

Predator-prey interactions of nematode-trapping fungi and nematodes: both sides of the coin

13 Nematophagous Fungi

Keywords

Introduction

Systematics of Nematode-Trapping Fungi

Key to Genera of Nematode-Trapping Fungi

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Key to Species of Arthrobotrys

Accepted Species of Arthrobotrys

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