Introduction

The family Clavariaceae is known to include clavarioid fungi (Singer 1975), but recent phylogenetic studies have classified three agaricoid genera within this family (Birkebak et al. 2013, 2016). Most of the species in these three genera were previously placed in a single genus Camarophyllopsis Herink (Arnolds 1986), but the majority has recently been combined in Hodophilus R. Heim ex R. Heim based on molecular support and type studies (Birkebak et al. 2016, Adamčík et al. 2018). Our previous phylogenetic studies on Hodophilus recognized two major lineages within the genus (Adamčík et al. 2016, 2017a, 2017b, 2018); the first corresponding to species without a distinctive odours that grouped in the H. micaceus superclade and the second to species with mainly a strong naphthalene odours that grouped in the H. foetens superclade. Species with dark dots on stipe previously identified as H. atropunctus represent two different species, placed in these two lineages but each in different one. These studies were specifically directed at foetid species or to members of the H. micaceus superclade with yellow or yellow-brown stipes. Within the latter lineage, there are two well-supported residual clades, one represented by a single North American species, H. hymenocephalus (A.H. Sm. & Hesler) Birkebak & Adamčík, and the other by some unidentified collections from Europe. Basidiomata in both residual clades have brown stipes without yellow or with yellow-brown tints, no darker dots on stipe and no foetid odours. Such morphotypes have been recognised in the European literature as C. hymenocephala (A.H. Sm. & Hesler) Arnolds or C. phaeophylla (Romagn.) Arnolds (Boertmann, 2012, Kovalenko et al. 2012). Recently, Arauzo and Iglesias (2018) identified one European residual clade as H. phaeophyllus (Romagn.) Arauzo & P. Iglesias and described H. hymenocystis Arauzo & P. Iglesias as a new species that is morphologically similar to H. phaeophylla but not closely related according to their analysis of ITS nrDNA region.

We could not trace any type collection nor authentic material, except the published figure, of C. phaeophylla, and a correct epitypification of this name relies on a good knowledge of species diversity and variability within the genus, as well as knowledge of the type locality. In this study, we want to test the concept of this name as proposed by Arauzo and Iglesias (2018) and to specify species limits and relationships within this last underexplored group of Hodophilus with brown stipes and non-naphthalene odours. We apply a similar approach as in our previous studies, and we base our study on available collections from different areas of Europe, analyse them by multi-locus phylogeny, and support the species delimitation by statistically evaluated morphological observations.

Materials and methods

Taxon sampling

Altogether, 25 European Hodophilus collections with brown stipes without yellow tinges, darker dots on stipe and naphthalene odours were analysed. For the phylogenetic placement, we used sequences previously published by Adamčík et al. (2018) supported by ITS sequences retrieved from Arauzo and Iglesias (2018). All sequences are presented in the Supplementary Table 1.

DNA extraction, PCR and sequencing

Three gene regions (nrITS, nrLSU and RPB2) were amplified, sequenced and analysed. Protocols of Birkebak et al. (2013) were followed for DNA extraction, PCR and sequencing. The primer pair ITS1F-ITS4 (Gardes and Bruns 1993, White et al. 1990) was used to amplify the ITS region. Combinations of LR0R-LR7, LR0R-LR5 or LR0R-LR16 (https://sites.duke.edu/vilgalyslab/files/2017/08/rDNA-primers-for-fungi.pdf) were used to amplify and sequence the nrLSU region. The primer pair b6F and b7.1R (Matheny 2005) was used to amplify and sequence the most variable region of the RPB2 gene between conserved domains 6 and 7. Sequencing was performed at the SEQme sequencing Company (Dobříš, Czech Republic).

Phylogenetic analyses

Sequences of individual gene regions were aligned using MAFFT online version 7 (http://mafft.cbrc.jp/alignment/server). The E-INS-I method (Katoh and Standley 2013) was selected for aligning the nrDNA ITS, the G-INS-I method (Katoh et al. 2005) for the nrDNA LSU, and the FFT-NS-I method (Katoh et al. 2002) for RPB2 region, all under default settings. Manual adjustments and concatenation of the individual alignments were done in SeaView 4 (Gouy et al. 2010). FastGap 1.2 (Borchsenius 2009) was used to code the phylogenetically informative indels in the ITS region following the simple indel coding algorithm (Simmons et al. 2001). Adding indel characters to the nucleotide alignment of ITS sequences increases the robustness of phylogenetic analyses (Nagy et al. 2012). After concatenating the nucleotide and binary data, the partitioned alignment was subjected to maximum likelihood (ML) and Bayesian inference (BI) phylogenetic analyses, which were performed in raxmlGUI (Silvestro and Michalak 2012) and MrBayes 3.1.2 (Ronquist et al. 2012), respectively. ML analysis was done using 1000 rapid ML bootstrap searches. The GTRGAMMA nucleotide substitution model was selected for the three nucleotide partitions (ITS, LSU, RPB2), and the default setting for binary data was used for the indel partition. BI was performed with the GTR + Γ + I model of evolution for the nucleotide partitions, and the two-parameter Markov model was set for the indel partition. The BI settings were as follows: four Markov chain Monte Carlo (MCMC) over 10 million generations, sampling every 1000th generation, two independent runs, and burn-in of 35% (the first 3500 trees were discarded). Post burn-in trees were used to compute a 50% majority rule consensus phylogram. Ramariopsis corniculata was chosen as the outgroup.

Phylogenetic trees from both ML and BI analyses resulted in largely congruent topologies (Fig. 1). ML bootstrap values (BS) > 70% and Bayesian posterior probabilities (PP) > 0.95 were considered evidence for statistical branch support. All sequences are deposited in GenBank. The concatenated final alignment has been deposited in TreeBASE (TB2:S25267).

Fig. 1
figure 1

Maximum likelihood (RAxML) phylogeny inferred from three loci (nrITS, nrLSU, RPB2) and additional indel coding of the ITS region. Newly generated sequences are highlighted in boldface. Names of taxa are followed by collection labels, country, and whether this represents a type collection. ML bootstrap values followed by Bayesian posterior probabilities are indicated at nodes. Clades not in focus in this paper are compressed

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Figs. 2–9
figure 2

Basidiomata field aspect of species in the H. phaeophyllus lineage. 2H. carpathicus (SLO2498, holotypus), photo S. Jančovičová. 3H. decurrentior (SAV F-3498, holotypus), photo V. Stanová. 4H. phaeophyllus in moist condition (LIP PAM00101902, epitype), photo P.-A. Moreau. 5H. phaeophyllus in dry condition (GC02092803), photo G. Corriol. 6H. stramineus in moist condition (SLO784), photo S. Jančovičová. 7H. stramineus in dry condition (SAV F-4836), photo D. Harries. 8H. stramineus in dry condition (PAM12072201), photo P.-A. Moreau. 9 Young basidiomata of H. stramineus (GC12112205), photo G. Corriol. Scale bar = 1 cm

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Morphological analyses

Macro-morphological descriptions were prepared from fresh material shortly after collection from the field. The number of full-length lamellae is treated in the species descriptions as “L”. The number of short lamellulae between each pair of full length lamellae is labelled as “l” (Vellinga 1988). Colour nomenclature standards follow Kornerup and Wanscher (1967).

Microscopic structures were examined on herbarium specimens in Congo red solution with ammonia after a short treatment in aqueous 10% KOH. The same micro-morphological characters were observed as those in our previous study on European Hodophilus species with naphthalene odours (Adamčík et al. 2017a). Pileipellis elements near the pileus margin and the pileus centre were observed and evaluated separately. Features were observed under an Olympus CX-41 microscope with an oil-immersion lens at a magnification of 1000×. All drawings of microscopic structures, with the exception of basidiospores, were made with a camera lucida using an Olympus U-DA drawing attachment at a projection scale of 2000×. Basidiospores were scanned with an Artray Artcam 300MI camera and measured by Quick Micro Photo (version 2.1) software. Enlarged scanned pictures of spores were used for measuring with an accuracy of 0.1 μm and for making line drawings. All other elements are measured with accuracy of 0.5 μm. Q is the length/width ratio of basidiospores and pileipellis elements. Statistics of microscopic dimensions are based on 30 measurements and given as a mean value plus/minus standard deviation; values in parentheses give measured minimum or maximum values.

Results

Phylogenetic analyses

The final dataset consists of 172 samples represented by 168 ITS, 116 LSU and 87 RPB2 sequences; 23 of them are published for the first time in this study. European collections of the genus Hodophilus are grouped in three monophyletic groups supported by both ML and BI analyses. These groups are described as new sections and are morphologically defined below. The section Hodophilus contains European and North American members with naphthalene odours and H. atropunctus that has no distinct odour and has dark dots on the stipe. Section Micacei also contains Hodophilus members from both continents; these have distinct yellow colour on at least some parts of the stipe, with the exception of H. variabilipes with yellow-brown colour and sometimes also darker dots on the stipe. All collections without distinct odours and without yellow colour and darker dots on the stipe are placed in section Phaeophylli. The latter section contains only European collections clustered with strong support in five clades corresponding to phylogenetic species. Based on morphology explained below, we assigned one species clade to the previously described H. phaeophyllus, and this species is designated as the type of the section. Three other species of this section are described as new in this study. One species clade (labelled as H. cf. phaeophyllus) is composed of three collections and is not further described in this study because of RPB2 amplification failure and absence of field descriptions. All sequences identified as H. hymenocystis by Arauzo and Iglesias (2018), including the type of the species, are placed in our H. phaeophyllus clade, suggesting synonymy of the two names. Sequences identified by these authors as H. phaeophyllus are placed in two different clades, one of them clustered within the H. cf. phaeophyllus clade and the other two within a new clade corresponding to H. stramineus.

Morphological delimitation of genetically defined species

Our previous taxonomic studies on the genus Hodophilus often showed little differences in microscopic structure and proved the importance of field characters for species circumscription. Among the five species recognised by phylogenetic analysis, one lacks any field notes, and therefore, we did not include it in our morphological analysis. Available descriptions and photographs allow us to conclude that all species of the studied lineage have brown stipes without conspicuous yellow tints or darker dots, and they all share an absence of a strong naphthalene odour. All four described species here have caulocystidia of a very irregular shape, which are often twisted or lobate, but this character was observed also in H. phaeoxanthus, a member of section Micacei (Adamčík et al. 2018).

Our observations of macro-morphological characters on the four studied species recovered differences especially in colour. Table 1 compares colours of different parts of the basidiomata retrieved from our own observations with the original description of H. phaeophyllus. To analyse the pileus colour, it is important to recognise if the basidiomata are in a fresh and moist condition or if they are dry, because pilei of all species are hygrophanous. In fresh condition, H. carpathicus, H. decurrentior and H. phaeophyllus have dark brown pilei and H. stramineus light brown (Figs. 2–9). The most dramatic change from moist to dry condition we observed in H. phaeophyllus that discolours to reddish grey or whitish (Figs. 4–5). The stipe also changes its colour during maturing. Most species develop darker brown colours towards the base when mature, and only H. carpathicus has dark brown colours already in young stages. The lamellae of H. stramineus are light brown also at maturity; we observed consistently darker brown lamellae colours in H. carpathicus and H. decurrentior, and the lamellae of H. phaeophyllus are initially pale whitish but soon turn to dark brown.

Table 1 Comparison of basidiomata colourations observed in European Hodophilus taxa of the H. phaeophyllus lineage. The colour codes follow Kornerup and Wanscher (1967)
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Figs. 10–28
figure 3

Microscopic structure of Hodophilus carpathicus (SLO2498, holotypus). 10 Caulocystidia. 11 Basidia. 12 Basidioles. 13 Spores. H. decurrentior (SAV F-3498, holotypus). 14 Caulocystidia. 15 Basidia. 16 Basidioles. 17 Marginal cells. 18 Spores. H. phaeophyllus (LIP PAM00101902, epitype). 19 Caulocystidia. 20 Basidia. 21 Basidioles. 22 Marginal cells. 23 Spores. H. stramineus (marginal cells SLO784, other elements SAV F-4836, holotypus). 24 Caulocystidia. 25 Basidia. 26 Basidioles. 27 Marginal cells. 28 Spores. Drawings by S. Jančovičová. Scale bar = 5 μm for spores, 10 μm for all other elements

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The collections that are assigned to H. phaeophyllus have a perfect colour match with the original diagnosis of the species, i.e. dark brown pileus colours turning to pale greyish-whitish when dry; stipe becoming darker near the base with age and lamellae developing a dark brown colour with age. Our data indicate that H. hymenocystis is a later synonym of H. phaeophyllus. Arauzo and Iglesias (2018) applied the name H. phaeophyllus for collections that fell within two different species (H. stramineus and an undescribed species, see Fig. 1). The species concept adopted by these authors is discussed further below.

Figs. 29–36
figure 4

Microscopic structure of Hodophilus carpathicus (SLO2498, holotypus). 29 Hyphal terminations in pileipellis near the pileus margin. 30 Hyphal terminations in pileipellis near the pileus centre. H. decurrentior (SAV F-3498, holotypus). 31 Hyphal terminations in pileipellis near the pileus margin. 32 Hyphal terminations in pileipellis near the pileus centre. H. phaeophyllus (PAM00101902, neotype). 33 Hyphal terminations in pileipellis near the pileus margin. 34 Hyphal terminations in pileipellis near the pileus centre. H. stramineus (SAV F-4836, holotypus). 35 Hyphal terminations in pileipellis near the pileus margin. 36 Hyphal terminations in pileipellis near the pileus centre. Drawings by S. Jančovičová. Scale bar = 10 μm

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Under the microscope, H. decurrentior is the only species easily distinguishable from all other members of the genus by higher spore Q > 1.4 (Table 2). The caulocystidia and terminal cells in the pileipellis near the pileus centre in H. carpathicus are very irregular in shape and size, with many small elements making their average length and width smaller than in other species of the studied lineage. In H. phaeophyllus, the broad marginal cells on the lamellae edges recall the terminal cells in the pileipellis. Sometimes, they are hard to find, disappear towards the stipe and are only present near the pileus margin, where the lamellae are very narrow. It is thus difficult to separate H. phaeophyllus from H. stramineus.

Table 2 Average values of 30 measurements of selected micro-morphological characters observed on the four species of the H. phaeophyllus lineage. Abbreviations: TC margin/centre and STC margin/centre, terminal and subterminal cells in pileipellis near the pileus margin or centre; L, length in μm; W, width in μm, Q, length/width ratio. Values in italics indicate important differences (with no or little overlap between at least one species pair). En dash indicates missing values due to absence of a structure or insufficient conditions of the studied herbarium specimen
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Below, we provide a preliminary key to European Hodophilus species described here and in our previous studies (Adamčík et al. 2017a, 2017b, 2018). We did not include H. fuscofoetens Arauzo, P. Iglesias & Fern.-Vic described recently by Arauzo and Iglesis (2018), because it is represented only by a single published ITS sequence that fall outside the genus Hodophilus in our analyses (not shown in the tree) and it may represent another genus of the family Clavariaceae. Another species described by these authors, H. praecox Arauzo, is distinguished by a different phenology (in spring), but the authors did not recognise any morphological differences, possibly because their description lack sufficient detail. We have included putatively the species in the key as morphologically close to H. anatinus due to the similar stipe coloration and relatively narrow terminal cells in the pileipellis reported in the original description, but particularly the second character should be investigated by observations from different parts of the pileipellis.

Taxonomy

Key to known European Hodophilus species

1 Basidiomata with distinct naphthalene odours and without conspicuous yellow colours on any part, subterminal cells in pileipellis rarely small (shorter than 5 μm), caulocystidia rarely lobate or twisted .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1* Basidiomata without strong and conspicuous naphthalene odours, sometimes with distinct yellow colours, subterminal cells in pileipellis frequently small, caulocystidia sometimes irregularly inflated, nodulose, lobate and twisted. . . . . . 5

2 Lamellae moderately close (L = 18–30). . . . .. . . . . . . . . . .3

2* Lamellae distant [L = 10–18(20)]. . . . . . . . . . . . . . . . . . . 4

3 Basidiomata becoming dark brown to black, especially near the pileus margin upon maturation or drying; caulocystidia on average wider than 7.5 μm . . . .. . .H. foetens

3* Mature or dry basidiomata not becoming darker; caulocystidia on average up to 7 μm wide . . .H. tenuicystidiatus

4 Pileus orange grey to greyish orange when fresh, drying pale dull orange; terminal cells of hyphae near the pileus centre with ratio of length/width mainly < 2.5. . . . . . . .H. pallidus

4* Pileus brown, grey brown, brownish grey, or when dry dark brown; terminal cells of hyphae near the pileus centre with ratio of length/width mainly > 2.5. . . . . . . H. subfoetens

5 Stipe with distinct dark dots. . . . . . . . . . . . . . . . . . . . . . . . .6

5* Stipe never with dark dots. . . . . . . . . . . . . . . . . . . . . . . . .7

6 Pileus becomes pale from the margin and darker at the centre when dry; stipe distinctly darker near the base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. atropunctus

6* Pileus becomes pale from the centre outwards and is uniformly coloured when dry; stipe uniformly coloured, usually yellow-brown. . . . . . . . . . . . . . . . . . . . . . . . . H. variabilipes

7 Stipe with distinct yellow colours at least on some parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7* Stipe without distinct yellow parts. . . . . . . . . . . . . . . . . 12

8 Young basidiomata completely yellow; stipe vivid yellow and remaining so even when mature. . . . . . . . . . . . H. micaceus

8* Young basidiomata with yellowish brown pileus; stipe colour soon changing and becoming partly to almost completely brown with age. . . . . . . . . . . .. . . . . . . . . . . . . . 9

9 Stipe starts to brown near the apex, terminal elements in pileipellis (at least near the centre) relatively narrow Q > 1.7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9* Stipe of young basidiomata near apex usually paler; terminal elements in pileipellis near pileus centre usually with Q < 1.6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

10 Stipe persistently vivid yellow, but when mature with olive and near apex also brownish tints, terminal elements in pileipellis (near pileus margin?) very narrow (Qav. = 2.5), fruiting in early season untill July. . . . . . . . . . . . . . . .H. praecox

10* Stipe of young basidiomata near apex usually darker yellow brown to grey brown; terminal elements in pileipellis near pileus centre with Qav. = 1.7–2.1, fruiting in August and later. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. anatinus

11 Stipe at first yellow to brownish yellow, in age gradually changing to dark grey brown to almost black near base; spores with Qav. ≤ 1.2. . . . . . . . . . . . . . . . . . . . . . . . . . .H. cambriensis

11* Stipe usually two-coloured with paler yellow, golden yellow, brownish orange near apex and light brown, yellowish brown or greyish brown colours near base, not becoming distinctly darker with age; spores usually with Qav. > 1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H. phaeoxanthus

12 Pileus and stipe usually uniformly yellow-brown; caulocystidia regular, not lobate or twisted. . . . H. variabilipes

12* Pileus and stipe without conspicuous yellow colours or stipe darker near the base; caulocystidia ± lobate and twisted. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

13 Spores narrowly ellipsoid, Qav. > 1.4. . .H. decurrentior

13* Spores broadly ellipsoid, Qav. < 1.3. . . . . . . . . . . . . . .14

14 All parts of basidiomata dark brown when young and in moist condition; pileus remains distinctly brown even when dry; caulocystidia and pileipellis at the pileus centre with elements of very different sizes. . . . . . . . . . . . . . H. carpathicus

14* Some parts of basidiomata, especially lamellae and adjacent surface of the stipe, pale brownish when young; pileus light brown or rapidly discolouring to light brown to almost whitish; caulocystidia and elements of pileipelis at the pileus centre of relatively similar size. . . . . . . . 15

15 Pileus with prevailingly light brown colours in moist and dry condition; lamellae light brown also at maturity . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . H. stramineus

15* Pileus dark brown when young or moist, strongly changing colour to pale grey or almost whitish; lamellae at first pale brownish and greyish then dark brown . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . . . H. phaeophyllus

Hodophilus section Hodophilus R. Heim

Type species: H. foetens (W. Phillips) Birkebak & Adamčík, Mycologia 108(5): 866. 2016

Diagnosis: Basidiomata typically with distinct naphthalene odours, one species without a distinct odour but with distinct dark dots on the stipe.

Hodophilus section Micacei Adamčík & Dima, sect. nov.

MycoBank No.: MB 833031.

Etymology: The name refers to epithet of the type species.

Type species: H. micaceus (W. Phillips) Birkebak & Adamčík, Mycologia 108(5): 867. 2016

Diagnosis: Basidiomata typically without distinct naphthalene odours and with yellow colour on the stipe, one species with yellow-brown stipe.

Hodophilus section Phaeophylli Adamčík & Dima, sect. nov.

MycoBank No.: MB 833032.

Etymology: The name refers to epithet of the type species.

Type species: H. phaeophyllus (Romagn.) Arauzo & P. Iglesias, Errotari 15: 330. 2018

Diagnosis: Basidiomata pale or dark brown, without distinct naphthalene odours, without yellow colour and dark dots on stipe.

Hodophilus carpathicus Jančovičová & Adamčík, sp. nov.

Figs. 2, 10–13, 29–30

MycoBank No.: MB 833033.

Etymology: The name refers to the Carpathian Mountains, the area of origin of the studied material.

Holotypus: Slovakia. Malá Fatra Mts, Kláštor pod Znievom, ca 1.5 km SE from the village center, 48° 57′ 48.93″ N, 18° 49′ 14.14″ E, alt. 481 m, old pasture with Juniperus shrubs, 13 Sep 2016, V. Kučera (SLO2498).

Diagnosis: All parts of basidiomata dark brown when young and in moist condition; pileus remains moderately brown also when dry; flesh without a strong odour. Spores subglobose to broadly ellipsoid, in average 4.6 × 3.9 μm, Qav. = 1.2; caulocystidia often strongly nodulose or lobate, flexuous or spirally coiled, sometimes coralloid, very irregular in size, in av. 28.9 × 6.9 μm.

Pileus 7–17 mm broad, hemispherical, convex to applanate, usually weakly depressed at the centre; margin often lobate, inflexed, even denticulate, when moist slightly translucently striate; surface matt, distinctly rugulose, weakly hygrophanous, when moist and fresh coffee brown (5F6) to chocolate (6F4) near the margin, coffee brown (5F7) at the centre; when dry mustard (5E6), coffee brown (5F7) near the margin and nougat (5D3) at the centre. Stipe 25–35 × 2–4 mm, usually narrowed towards the base, often longitudinally compressed, flexuous especially towards the base, hollow; smooth, glabrous, matt; when young uniformly coloured, dark brown (chestnut 6F7); when mature paler near the lamellae, coffee brown (5F7), and near the base mustard brown (5E6). Lamellae L 22–24, l 0–1, up to 2 mm wide, decurrent, tobacco brown (5F6) to chocolate brown (6F4); edge entire, concolorous. Flesh elastic, nougat (5D3) in pileus; odour indistinct, with weakly unpleasant component when drying (sweaty).

Basidiospores (4.2)4.4–4.9(5.5) × (3.4)3.6–4.1(4.4) μm, av. 4.6 × 3.9 μm, Q = (1.07)1.13–1.26(1.42), Qav. = 1.2, subglobose to broadly ellipsoid, hyaline, smooth, thin-walled. Basidia 4-spored, narrowly clavate, (27)32–42(46) × 6–7(8) μm, av. 37.1 × 6.6 μm. Basidiola cylindrical to narrowly clavate, obtuse, (13)19–33(40) × (2.5)3–5(6) μm, av. 26.1 × 4.1 μm. Pleurocystidia absent. Well defined marginal cells not observed. Pileipellis a hymeniderm, rarely a transition to an epithelium; terminal cells near the pileus margin obpyriform, ellipsoid or broadly clavate, often with thickened walls (up to 1 μm), often with dark brown parietal pigments and dark brown incrustations on subterminal cells, (15)20.5–43.5(78) × (9)12–25.5(35) μm, av. 32 × 18.8 μm, Q = (1.08)1.3–2.23(3.18), Qav. = 1.76; subterminal cells usually distinctly narrower, rarely inflated, unbranched, (2)8–30(42) × 4–12(22.5) μm, av. 19.1 × 8 μm; small cells (shorter than 5 μm) rare or occasional. Terminal cells near the pileus centre often narrower than those near the pileus margin, (8.5)18–37.5(53) × (6.5)10–21.5(31) μm, av. 27.8 × 15.5 μm, Q = (0.83)1.07–2.81(6.46), Qav. = 1.94, variable in shape and size, some obpyriform or ellipsoid and very variable in size, others narrower and clavate; subterminal cells similar to those near the pileus margin, (2)9.5–35(54) × (2.5)4.5–13.5(21.5) μm, av. 22.4 × 8.8 μm. Caulocystidia without dark pigments, thin-walled, repent, usually densely clustered; often strongly nodulose or lobate, flexuous or spirally coiled, often ventricose, sometimes coralloid, occasionally clavate and regular, obtuse, very variable in size (10)14–44(82) × (3)4–10(16.5) μm, av. 28.9 × 6.9 μm. Clamp connections absent in all parts.

Additional material examined: Slovakia. Malá Fatra Mts, Kláštor pod Znievom, ca 1.5 km SE from the village centre, 48° 57′ 48.93″ N, 18° 49′ 14.14″ E, old pasture with Juniperus shrubs, alt. 481 m, 13 Sep 2016, V. Kučera (SLO2499).

Hodophilus decurrentior Adamčík, Jančovičová, Læssøe & Dima, sp. nov.

Figs. 3, 14–18, 31–32

MycoBank No.: MB 833034.

Etymology: The name refers to the deeply decurrent lamellae.

Holotypus: Slovakia. Záhorská nížina Lowland, Závod village, Abrod National Nature Reserve, 48° 32′ 0″ N, 17° 0′ 25″ E, on soil in low repent scrubs of Salix sp. and tall vegetation of Molinia caerulea, 30 Sep 2002, S. Adamčík (SAV F-3498).

Diagnosis: Pileus greyish brown (7F3), when dry hair brown (5E4); stipe concolorous but paler near the lamellae and at the base; lamellae usually deeply decurrent, brown (6E4); flesh without a strong odour. Spores narrowly ellipsoid to oblong, av. 5.9 × 3.8 μm, Q = 1.37–1.74, Qav. = 1.56; caulocystidia clavate, frequently flexuous, occasionally curved, av. 33.7 × 8 μm; pileipellis mainly a hymeniderm, terminal cells near the pileus margin with average Q > 1.76.

Pileus 5–13 mm broad, hemispherical to convex, not or weakly depressed at the centre; margin inflexed also at maturity, crenate, when moist weakly translucently striate up to 3 mm; surface matt, smooth, rugulose at the centre, hygrophanous, when moist and fresh greyish brown (7F3), when dry hair brown (5E4). Stipe 18–25 × 1–3 mm, narrowed towards the base, flexuous; smooth, matt; concolorous with pileus but near apex and at the base paler. Lamellae L = 11–19, l = 0–1, deeply decurrent, brown (6E4); edge entire, concolourous. Flesh fragile; grey-brown, unchanging; odour indistinct.

Basidiospores (4.9)6.3–6.5(7.5) × (3.3)3.5–4.1(4.5) μm, av. 5.9 × 3.8 μm, Q = (1.27)1.37–1.74(2.21), Qav. = 1.56, ellipsoid to oblong, hyaline, smooth, thin-walled. Basidia 4-spored, rarely 2-spored, narrowly clavate, (30)32.5–41(47) × (5)5.5–7(7.5) μm, av. 36.5 × 6.2 μm. Basidiola cylindrical to narrowly clavate, obtuse, (11)21–33.5(38) × (3)3.5–5.5(7) μm, av. 27 × 4.5 μm. Pleurocystidia absent. Well-differentiated marginal cells on the lamellar edges observed only near the pileus margin of SAV F-3498, narrowly or broadly clavate, occasionally subcylindrical or lageniform, rarely sphaeropedunculate, apically obtuse, (15.5)19.5–29.5(41) × (3.5)5.5–9(11.5) μm, av. 24.5 × 7.3 μm. Pileipellis a hymeniderm, rarely a transition to an epithelium, with intrapariental pigments especially at subterminal cells; terminal cells near the pileus margin obpyriform, sphaeropedunculate, subglobose or broadly clavate, walls not distinctly thickened (up to 0.5 μm thick), (20)24–45.5(63) × (10.5)14.5–26(38) μm, av. 34.7 × 20.3 μm, Q = (1)1.27–2.26(3.76), Qav. = 1.76; subterminal cells usually distinctly narrower, cylindrical, rarely inflated, not branched, (2.5)5.5–31(65) × (2)3.5–10(19) μm, av. 18.3 × 6.7 μm; small cells (shorter than 5 μm) rare or occasional. Terminal cells near the pileus centre similar in size and shape, (13)25–47(59) × (9)13.5–25.5(33) μm, av. 35.9 × 19.5 μm, Q = (1)1.33–2.54(3.46), Qav. = 1.93, occasionally nodulose near the bases; subterminal cells more frequently inflated, (2)11–38(59) × (3)4–13.5(25) μm, av. 24.6 × 8.6 μm. Caulocystidia without dark pigments, thin-walled, ascending or repent, usually clustered in patches; terminal cells mostly narrowly clavate to clavate, rarely ventricose, often pedunculate, frequently flexuous, occasionally curved to twisted, obtuse, (18)24–43.5(51) × (6)6.5–9.5(12) μm, av. 33.7 × 8 μm. Clamp connections absent in all parts.

Additional material examined: Norway. Oslo, Gressholmen, 59° 53′ 02.04″ N, 10° 43′ 07.32″ E, in grass turf on calcareous rocks, 7 Oct 2013, T. Læssøe & A. Molia NOBAS2878-16 (O-F-21872); ibid., 16 Oct 2012, T. Læssøe & A. Molia NOBAS2999-16 (O-F-245610).

Hodophilus phaeophyllus (Romagn.) Arauzo & P. Iglesias, Errotari 15: 330. 2018

Figs. 4–5, 19–23, 33–34

≡ Hygrophorus rugulosus var. phaeophyllum Romagn., Bull. trimest. Soc. mycol. Fr. 86: 874. 1971

≡ Camarophyllopsis phaeophylla (Romagn.) Arnolds, Mycotaxon 25(2): 643. 1986

≡ Hygrotrama phaeophylla (Romagn.) Arnolds, Persoonia 12(4): 477. 1985

≡ Hygrotrama rugulosa var. phaeophylla (Romagn.) [as “rugulosus var. phaeophyllus”] Bon, Doc. Mycol. 7(27-28): 46. 1977

Holotypus: France. Forêt de Coye, le Caillou Blanc, à Chaumontel (V. d’O.), 12 Sep 1951, Romagnesi 51.267 [no specimen located in Romagnesi’s herbarium in PC].

Lectotypus (designated here): Bull. trimest. Soc. mycol. Fr. 86: 872, Fig. 3. 1971. MycoBank typification number MBT389233.

Epitypus (designated here): France. Pas-de-Calais. Terril de Pinchonvalles, thickets of Crataegus and Betula, on soil, 19 Oct 2000, P-A Moreau (LIP PAM00101902). MycoBank typification number MBT389232.

= Hodophilus hymenocystis Arauzo & P. Iglesias, Errotari 15: 317. 2018

Original diagnosis: A typo differ colore magis e fusco murino ac lamellis brunneis.

Emended diagnosis: Pileus near the margin pale brown to brown (6D3–6E5), at the centre dark brown (6F6), when dry reddish grey (7B2) to whitish; stipe concolorous but when young paler near the apex and at the base; lamellae first whitish when mature dark brown (6F6); flesh without a strong odour. Spores broadly ellipsoid to ellipsoid, av. 4.7 × 3.7 μm, Q = 1.17–1.37, Qav. = 1.27; caulocystidia mainly clavate to broadly clavate, av. 31.1 × 10.7 μm; pileipellis mainly a hymeniderm, terminal cells near the pileus margin with Qav. = 1.36.

Pileus 5–15 mm broad, hemispherical to convex, slightly depressed at the centre; margin inflexed, crenate, when moist weakly translucently striate; surface matt, rugulose, veined, hygrophanous; when moist and fresh brown (6E5) to greyish brown/café-au-lait (6D3) near the margin, dark brown/burnt amber (6F6) at the centre, when dry reddish grey (7B2) to whitish. Stipe 20–30 × 1.5–2.5 mm, sometimes enlarged near lamellae up to 3.5 mm, narrowed towards the base, flexuous, tortuous; pruinose, white powdery to white fibrillose, the base covered by sparse white mycelium; near the apex at first whitish, orange grey (5B2), to light ochre, then flesh brown (6B3) brownish orange (7C3), towards the base whitish, then reddish grey (7B2) to dark brown (7F4). Lamellae L = 12–16, l = 0–1, up to 2 mm wide, deeply decurrent, whitish (5A2), then reddish grey (7B2), brownish orange (6C3) to dark brown (6F6). Flesh fragile; odour faint or herbaceous earthy.

Basidiospores (4.1)4.3–5(6) × (3.1)3.4–3.9(4.2) μm, av. 4.7 × 3.7 μm, Q = (1.1)1.17–1.37(1.58), Qav. = 1.27, broadly ellipsoid to ellipsoid, hyaline, smooth, thin-walled. Basidia 4-spored, hyaline, narrowly clavate and slightly flexuous toward the base, (26)29.5–38.5(47) × (4.5)5–6.5(7) μm, av. 34.1 × 5.9 μm. Basidiola cylindrical to narrowly clavate, often flexuous, obtuse, (15)24–35.5(40) × (2.5)3.5–5.5(7) μm, av. 29.5 × 4.4 μm. Pleurocystidia absent. Marginal cells observed in one collection only (PAM05100301), well differentiated, clavate to sphaeropedunculate, sometimes flexuous towards the base, rarely nodulose, obtuse, (16)20–35.5(45) × (7)8–11(12.5) μm, av. 27.7 × 9.7 μm. Pileipellis a transition between a hymeniderm and an epithelium; terminal cells near the pileus margin subglobose, obpyriform, thin-walled or only with indistinctly thickened walls, (15)21.5–43.5(68) × (10)18.5–29.5(40) μm, av. 32.7 × 23.9 μm, Q = (1)1.07–1.65(2.43), Qav. = 1.36; subterminal cells usually distinctly narrower, cylindrical, rarely inflated, occasionally branched, (3)4–30.5(94) × 3–11(29) μm, av. 17.4 × 6.8 μm; small cells (shorter than 5 μm) occasional. Terminal cells near the pileus centre similar in size and shape to those near the pileus margin, (17)23.5–43(55) × (8)17.5–29.5(37) μm, av. 33.5 × 23.4 μm, Q = 0.97–2.04(5.25), Qav. = 1.48; subterminal cells also similar to those near the pileus margin, (3)9.5–31(46) × (3)3.5–11(22) μm, av. 20.2 × 7.4 μm. Caulocystidia without dark pigments, thin-walled, repent or ascending; terminal cells mainly clavate to broadly clavate, rarely obpyriform, occasionally pedunculate or flexuous towards the base, apically obtuse, (11)21–41.5(65) × (6)7.5–14(21.5) μm, av. 31.1 × 10.7 μm. Clamp connections absent in all parts.

Additional material examined: France. Doubs. Boujailles, maison forestière de Chevreuille, among needles under Thuja sp., 3 Nov 2005, J-M. Moingeon PAM05100301 (LIP 0401638); Hautes-Pyrénées, ravin de la Tapère, Buxus litter, on calcareous soil, 28 Sep 2002, G. Corriol (BFF GC02092803). Germany. Thüringen. Jena, Jenaer Forst, on soil, 27 Sep 2014, T. Böhning C8-AG20; Thüringen, Jena, Nordfriedhof, 28 Jul 2009, A. Gminder E07 sp AT H5.

Hodophilus stramineus Jančovičová, Dima & Adamčík, sp. nov.

Figs. 6–9, 24–28, 35–36

MycoBank No.: MB 833035.

Etymology: The name refers to the pale straw colour of dry pilei.

Holotypus: United Kingdom. Wales. Pembrokeshire, Orielton Wood, Orielton Field Study Centre, 51° 39′ 10.55″ N, 4° 57′ 03.25″ W, on ground at woodland edge associated with Fraxinus, Acer, Quercus, Corylus, Hedera helix and Rubus, 8 Oct 2016, D. Harries (SAV F-4836).

Diagnosis: Pileus light brown to moderately brown (6D3 to 5C4, 6C2, 4–5F7), fading to even paler yellowish brown or grey-brown colours when dry (5B3–B4); stipe with pale brownish, yellowish and greyish tints near the lamellae, darker grey-brown towards the base, where it becomes even darker when old; flesh without a strong odour. Spores in average 4.4 × 3.6 μm, Qav. = 1.24; pileipellis mainly a hymeniderm, terminal cells of the hyphae near the pileus centre mainly obpyriform, broadly clavate or sphaeropedunculate, with Qav. < 1.46.

Pileus 5–21 mm broad, convex to plano-convex, usually weakly depressed at the centre; margin inflexed, slightly crenate, when moist translucently striate up to half the radius; surface matt, smooth, sometimes rough or rugulose at the centre, when dry locally cracking and forming a fine granulose structure, hygrophanous; when moist and fresh greyish brown/café-au-lait (6D3) or paler brown near the margin, darker, brownish orange/golden blonde (5C4), brownish grey (6C2), olive brown (4F7–5F7) at the centre, when dry greyish orange (5B3), yellowish brown/ hair brown (5E4) to bronze (5E5), grey brown (5C3) or greyish yellow/champagne (4B4). Stipe 12–35 × 1–4 mm, cylindrical, usually narrowed towards the base, sometimes flexuous; smooth, shiny, sometimes near lamellae pruinose or granulose; near the lamellae orange grey (5B2), brownish orange (5C3), blonde (4C4), beige (4C3), greyish yellow/champagne (4B4); towards the base darker, at first greyish brown/nougat (5D3), soot brown (5F5), then dark brown/chocolate (6F4) or chestnut (6F6, 6F7). Lamellae L = 12–31, l = 0–1, up to 3 mm wide, decurrent to deeply decurrent, usually darker than pileus surface, young brownish orange (5C4), mature yellowish brown (5E4, 5E7) or brownish orange (6D3); edge entire, when young pale whitish, when old concolourous. Flesh elastic, beige; odour indistinct, with a faint unpleasant component.

Basidiospores (3.9)4.1–4.7(5.4) × (2.9)3.3–3.8(4.3) μm, av. 4.4 × 3.6 μm, Q = (1.08)1.18–1.3(1.5), Qav. = 1.24, broadly ellipsoid, hyaline, smooth, thin-walled. Basidia 4-spored, narrowly clavate, (25)30.5–38(44) × (4.5)5–6(7) μm, av. 34.2 × 5.7 μm. Basidiola cylindrical to narrowly clavate, obtuse, (14)21.5–33(42) × (3)3.5–5(6) μm, av. 27.2 × 4.4 μm. Pleurocystidia absent. Well defined marginal cells on the lamellae edges observed only in one collection (SLO784), mainly clavate, occasionally ellipsoid or obpyriform, obtuse, (10)12.5–24.5(34) × (4.5)5–8(10.5) μm, av. 18.4 × 6.6 μm. Pileipellis a hymeniderm, rarely a transition to an epithelium; terminal cells near the pileus margin obpyriform, broadly clavate or sphaeropedunculate, often with thickened walls (0.5–1 μm), (14)23.5–43.5(65) × (9)16.5–31(41) μm, av. 33.4 × 23.8 μm, Q = (0.7)1.04–1.88(4.21), Qav. = 1.46; subterminal cells usually distinctly narrower, thin-walled, cylindrical, rarely inflated and branched, (2)4.5–23.5(50) × (2)4–10.5(33) μm, av. 14 × 7.1 μm; small cells (shorter than 5 μm) rare or occasional. Terminal cells near the pileus centre similar to those near the pileus margin, (10)25–43(65) × (10)16–29(49) μm, av. 34 × 22.6 μm, Q = (0.79)1.09–2.07(4.7), Qav. = 1.58; subterminal cells also similar, (2)4–24(54) × (2)3.5–10(22) μm, av. 14.1 × 6.6 μm. Caulocystidia without dark pigments, thin-walled, ascending or repent; terminal cells mostly narrowly clavate to clavate, frequently flexuous or twisted, occasionally nodulose, apically obtuse, (10)23.5–47(69) × (5)6–13.5(26) μm, av. 35.3 × 9.7 μm. Clamp connections absent in all parts.

Additional material examined: France. Pas-de-Calais, Eperlecques, wet plantation of Alnus incana with Molinia caerulea, 22 Jul 2012, P.-A. Moreau PAM12072201 (LIP0401639); Hautes-Pyrénées: Castet de Gerde, broadleaf forest, on clay soil, 12 Nov 2012, G. Corriol (BFF GC12112205). Norway. Oslo, Bygdøy, Reinsdyrlia, on soil in Tilia-Corylus forest, 16 Sep 2015, T.E. Brandrud, B. Dima, DB5776 / TEB373-15 (O). United Kingdom. England. S Somerset, Swell Wood, near Fivehead, on bare, damp soil, under Corylus avellana, 18 Sep 2008, N.W. Legon (KM161018); Wales. Powys, Gregynog grounds, 24 Oct 2014, pasture on edge of Quercus forest, on soil, R. Foster (SAV F-4399). Slovakia. Podunajská nížina Lowland, Banka village, near the Koliba pod Ahojom, scrubs on the forest margin, on soil, 26 Sep 2014, S. Jančovičová (SLO782, SLO784); Malé Karpaty Mts, Plavecké Podhradie village, margin of meadow, near deciduous forest, 19 Oct 2014, S. Jančovičová (SLO507); Poľana Mts, Zvolen city, Arborétum Borová hora, soil on a stream bank, 30 Sep 2009, S. Adamčík (SAV F-3096; SAV F-3097). Germany. Thüringen, Jena, Rautal, on soil, 28 Sep 2014, T. Böhning TB14/075; Thüringen, NP Hainich, on soil, 15 Sep 2014, T. Böhning C12-AG34; Germany, Thüringen, Craula, NP Hainich, 31 Oct 2013, A. Gminder A08 sp AT H9; Thüringen, Hütscheroda, NP Hainich, 12 Nov 2013, A. Gminder C08 sp AT H11.

Discussion

How much can we trust morphology?

When discussing the situation and recent changes in species circumscriptions within the genus Hodophilus with other mycologists, we received feedbacks like “yesterday, species identification was easy and tomorrow it will be difficult”. Indeed, previous species concepts were easy: all collections with naphthalene odours were identified as H. foetens, all with dark dots as H. atropunctus, with yellow stipes as H. micaceus and those collections without these marked characters were assigned to H. hymenocephalus or H. phaeophyllus (e.g. Boertmann 2012). Surprisingly, this easy concept of four species was supported also by earlier phylogenetic studies (Kovalenko et al. 2012). Studies of Adamčík et al. (2017a, 2017b, 2018) confirmed one after another that naphthalene odour, dark dots on stipes and yellow colours on stipes are characters associated with a range of phylogenetically defined species. Moreover, the study on species with dark dots demonstrated that odour and dark dots on the stipe are plesiomorphic characters present in unrelated lineages of the genus.

Our current study is dealing with the last unexplored group, representing the residual morphotypes not displaying any of above mentioned striking characters. We demonstrated that this group is represented by at least five species in Europe, four of which we describe here. Surprisingly, the residual European morphotypes are grouped in a single monophyletic lineage. However, our initial field identifications taught us that the morphological delimitation of this particular group is highly intriguing. Several members of the H. micaceus lineage may lose the yellow colour on the stipe with age and thus become very similar to any of the species in the H. phaeophyllus lineage. To avoid mistakes, identification should be based on collections with a least some young basidiomata. Some collections of H. variabilipes without dots may be similar especially to H. stramineus since both have yellow-brown colours, but the colours of the latter are duller and much paler when fresh or young and the stipe becomes darker towards the base.

We are aware that our current proposal for species circumscription is based on relatively few well annotated collections and may not cover the variability of characters sufficiently. Moreover, potential undiscovered species of the genus may reshuffle the distinguishing characters and the key. One undescribed species is present in our phylogeny represented by three ITS sequences. One sequence was obtained from a collection sent by Felix Hampe, who provided also a photograph showing very dark brown basidiomata similar to H. carpathicus. Also, a sequence with accession number MK139804 of collection ERRO-2013112801 identified by Arauzo and Iglesias (2018) as H. phaeophyllus belongs to this undescribed species and Fig. 23 in their study made by Patrice Tanchaud probably corresponds to this collection and shows also very dark brown basidiomata. Further phylogenetic and morphological delimitation of this species will require new, well annotated collections, further work behind the microscope and more sequence work.

Brown odourless Hodophilus species in European literature

The oldest name used for the residual brown morphotypes corresponding to the H. phaeophyllus lineage is Hygrophorus hymenocephalus A.H. Sm. & Hesler described from Tennessee, USA (Smith and Hesler 1940), recently combined in Hodophilus (Birkebak et al. 2016). A decade later, the species was reported from Denmark (Lange and Hansen 1950) and soon from England (Hora and Orton 1955). At that time, it was believed that different species of the genus (as Hygrophorus) may have a transoceanic distribution in Europe and North America and as a consequence, Romagnesi (1971) described H. rugulosus var. phaeophyllus Romagn. as a colour variety of the North American species H. rugulosus A.H. Sm. & Hesler also recently combined in Hodophilus (Adamčík et al. 2018). Arnolds (1986, 1990), who raised Romagnesi’s variety to species rank (in the genus Camarophyllopsis) believed that H. hymenocephalus occurred in Europe but was distinct from H. phaeophyllus. Boertmann (2012) treated the names as synonyms. Nevertheless, there is no evidence of transoceanic distributions within the genus (e.g. Birkebak et al. 2016); H. hymenocephalus is placed apart from the H. phaeophyllus lineage in our tree and the use of this name should be abandoned in Europe.

Our publication raises the number of known species in the H. phaeophyllus lineage from one or two previously accepted (H. hymenocephalus and H. phaeophyllus) to four described here and one undescribed species. We are fairly sure, that none of the previous publications included H. decurrentior, due to the deviating spore shape. Hora and Orton (1955) and Printz and Læssøe (1986) described the colours of H. hymenocephalus as dark brown without mentioning distinct discolourations that may correspond to H. carpathicus or the dark undescribed species recovered in our phylogeny. Surprisingly, three different publications described H. phaeophyllus (Moser 1978, Horak 2005) or H. hymenocephalus (Lange and Hansen 1950) with darker colours during maturation. This does not correspond to any species described in our study. We are not sure, whether this darkening species corresponds to the undescribed species in our phylogeny, or to another species, or if these descriptions are based on mixed collections, because species of Hodophilus often co-occur in small hotspots. Arnolds (1990) gave his description of H. phaeophyllus with colour codes according to Kornerup and Wanscher (1967), thus we were able to compare colours with our descriptions. The pileus colours of the Arnolds’ description cover both H. phaeophyllus and H. stramineus in our observations (Table 1). It is apparent, that without sorting of collections to phylogenetic species, sorting out the colour variation and dissimilarities were impossible. Kovalenko et al. (2012), who published the first limited phylogeny of Hodophilus (as Camarophyllopsis sensu lato) based on tef1α, provided the only description of H. phaeophyllus that fits well to the concept of the species presented and typified in this study.

Recently, Arauzo and Iglesias (2018) recognised two European species that morphologically correspond to the H. phaeophyllus lineage, one as new, H. hymenocystis, and H. phaeophyllus. They distinguish the former by the presence of marginal cells at the lamellae edges and the paler colour of lamellae and pileus. Our colour comparison of the four species described in this study with the original description of H. phaeophyllus showed that its best match is within the species clade that contains an ex-type sequence of H. hymenocystis. There are two reasons why Arauzo and Iglesias (2018) applied their new name for H. phaeophyllus. Firstly, sequences identified by these authors as H. phaeophyllus belong to two different species according to our phylogeny: to the pale-coloured H. stramineus and to a dark coloured undescribed species. Secondly, the presence of marginal cells is not a constant feature within the species according to our earlier studies (Adamčík et al. 2018) and our current observations confirmed it (Table 1.). Arauzo and Iglesias (2018) argued that the original description of H. phaeophyllus reported an absence of marginal cells. Romagnesi (1971) described together with Hygrophorus rugulosus var. phaeophyllus also H. phaeoxanthus in the same paper, and for both he did not mention any defined elements of the lamellae edges. The type study of H. phaeoxanthus (Adamčík et al. 2018), however, revealed presence of marginal cells. To our experience, these elements are difficult to observe and are easily overlooked due to often very limited material (small basidiomata).

Ecology and distribution

According to our observations, members of the H. phaeophyllus lineage are the rarest in Europe compared to the other two phylogenetic groups of the genus. Hodophyllus phaeophyllus and H. stramineus, both known from France, Germany and Spain, the latter also from Great Britain and Slovakia, maybe the most common and widespread within the lineage. Collections of the undescribed species in our phylogeny originate from Spain, Great Britain and Germany. Hodophilus decurrentior is only known from Norway and Slovakia, but this is unlikely to reflect the true distribution. Hodophilus carpathicus is only known from two collections from the same site, but some descriptions of dark basidiomata from other sites may correspond to this species. The ecology of our collections is similar to other groups of the genus: grasslands, scrubs, forest margins or non-ectomycorrhizal woods, often on heavy clay soils with high pH. They may occur in mass fruitings with several species involved. At one small site in Denmark covering about 50 × 50 m all the classic four “species” co-occurred and produced thousands of fruitbodies. They were associated with Camarophyllopsis schulzeri, many clavarioid species and a long list of Geoglossaceae and Entoloma species. The known occurrences of the genus suggest that its members prefer a humid climate with high annual rainfall or relatively stable humid conditions but known sites vary a lot in terms of climatic conditions and amount of exposure from completely open dry grassland to very wet closed forests such as alder carrs with lime deposits.