Dermoloma murinellum Horak

Adamčíková, Katarína, Kiran, Munazza, Caboň, Miroslav, Matheny, Brandon P., Sánchez-García, Marisol, Arnolds, Eef, Caboňová, Michaela, Corriol, Gilles, Dima, Bálint, Friebes, Gernot, Griffith, Gareth W., Grootmyers, Django, Harries, David, Karich, Alexander, Mešić, Armin, Mihaljevič, Martin, Moreau, Pierre-Arthur, Pošta, Ana, Shapkin, Vasilii, Tkalčec, Zdenko, Vizzini, Alfredo, Vondrovicová, Lenka, Adamčík, Slavomir & Jančovičová, Soňa, 2025, A phylogenetic and morphological study of the genus Dermoloma (Agaricales, Tricholomataceae) in Europe and North America exposes inefficiency of opportunistic species descriptions, IMA Fungus 16, pp. e 157337-e 157337 : e157337-

Dermoloma murinellum Horak , Sydowia 39: 110. 1987.

Figs 35 e , 38

Holotype.

Switzerland • Graubünden, N des Albulpasses ( Terrassas ), elev. 2450 m, 30 Aug 1982, E. Horak ZT 1573 ( ZT Myc 42786 ).

Distinguishing characters.

European species; basidiomata small, mycenoid; pilei 8–22 mm in diameter; stipes 1–2 mm wide; lamellae ash-gray; spores amyloid, ellipsoid to oblong, 5.8–6.7 × 3.7–4.4 μm; caulocystidia narrowly clavate or narrowly fusiform, 4–6 μm wide.

Pileus 8–22 mm; when young conical-campanulate, when mature plano-convex with broad, rounded umbo; margin shortly enrolled, entire to slightly crenulate; surface matt, rugulose, densely minutely wrinkled, strongly hygrophanous; color when young or wet very dark gray-brown to almost black, when mature fading to dull ochre-gray with some lilac shade at center. Stipe 15–35 × 1–2 mm; cylindrical, flexuous to undulate-bumped; surface densely pruinose when young, remaining pruinose only at apex when mature; color blackish gray all over, with age fading to ochraceous gray-brown from apex towards the base. Lamellae distant, L = 12–16, l = 1–3; adnate-emarginate; color ash-gray, when mature rather lighter yellowish ochre; edges truncate, concolorous, entire. Context whitish to somewhat flesh-colored in pileus, gray-brown in stipe; odor farinaceous.

Spores (5.5 –) 5.8–6.2 – 6.7 (– 7.8) × (3.4 –) 3.7–4 – 4.4 (– 4.8) μm; ellipsoid to oblong, Q = (1.34 –) 1.41–1.55 – 1.69 (– 1.86); walls amyloid; hilar appendage ca. 0.5–1 μm long. Basidia (21 –) 25–28.7 – 32 (– 40) × 6–6.5 – 7.5 μm; clavate; with 2 or 4 sterigmata. Basidioles first cylindrical, then clavate, ca. 4–6.5 μm wide. Marginal cells (17 –) 20–24.7 – 29.5 (– 40) × (3 –) 3.5–4.8 – 6 (– 7) μm; clavate, cylindrical or fusiform, often flexuous, occasionally moniliform, sometimes diverticulate or nodulose, apically obtuse or constricted. Pileipellis 65–100 μm deep; suprapellis 40–65 μm deep, of one or two layers of inflated, densely arranged cells; subpellis not well-differentiated, 20–30 μm deep, of densely packed, horizontally oriented, intricate, 3–10 μm wide hyphae, gradually passing to horizontally oriented hyphae in trama; hyphal terminations with yellow-brown parietal pigments but on subterminal cells also incrusted pigments, with usually slightly or distinctly thickened walls up to 1 μm. Terminal cells near pileus margin (13 –) 25.5–36.6 – 47.5 (– 60) × (6 –) 10–20.3 – 30 (– 44) μm; obpyriform, sphaeropedunculate or clavate, occasionally lobate; subterminal cells narrower and subcylindrical or ventricose-fusiform, occasionally laterally swollen, often branched. Terminal cells near pileus center (14 –) 21.5–34.8 – 48 (– 73) × (7 –) 11.5–20.5 – 29.5 (– 45) μm; mainly clavate, occasionally sphaeropedunculate or obpyriform, towards septa often narrowed and flexuous; subterminal cells more frequently branched. Caulocystidia (26 –) 31.5–38.8 – 40 (– 53) × (3 –) 4–5 – 6 (– 6.5) μm; cylindrical, narrowly clavate, occasionally narrowly fusiform, apically obtuse or slightly acute or constricted, often flexuous, occasionally nodulose; thin-walled, with brownish yellow parietal pigments. Clamp connections present.

Distribution and ecology.

This species is only known from the type collecting area in Swiss Alps; probably restricted to alpine habitats, but insufficiently known.

Additional material studied.

Switzerland • Albulapass (Graubünden), alpine grassland under Cirsium spinosissimum , elev. 2300 m, 2 Sep 2006, A. Leuchtmann and P. - A. Moreau PAM 06090203 ( LIP) .

Notes.

Dermoloma murinellum has amyloid spores and belongs to D. subgenus Amylospora , section Atrobrunnea . It has small mycenoid basidiomata but is placed within a clade of species with mainly collybioid basidiomata (Fig. 2 ). The species exhibits almost all characters with transitional stages between morphological groups defined in this study and is therefore very difficult to identify. The basidiomata are at the upper limit of the mycenoid size (pilei up to 15 mm, stipes up to 2 mm wide), the spores are of intermediate size and shape in D. section Atrobrunnea , the marginal cells are not well differentiated, and the caulocystidia are relatively slender. Morphological identification requires special attention; we therefore recommend to combine the heat map (Fig. 4 ), the key and other data available in this study to achieve a better probability of correct identification, and in case of uncertainty, an ITS sequence should be used for verification. Dermoloma murinellum is the only species of the genus described from the cold alpine habitat of the European Alps ( Switzerland) ( Horak 1987). Our collection LIP (PAM 0690203) was included in the phylogenetic study by Sánchez-García et al. (2021). It is originating from the type collecting area and our morphological study confirmed that it matches the type of D. murinellum . It was collected in alpine grasslands, but according to our observations it seems that several species from lowlands can occur at higher elevation in the alpine habitat. For example, we collected D. compactum , D. griseobasale and D. josserandii in the Pyrenees at an elevation of ca. 1800 m. Furthermore, the Albulapass locality is not far from timberline and mixed alpine and subalpine influences with, e. g., Amanita pantherina and Boletus edulis associated with herbaceous vegetation (A. Leuchtmann, pers. comm.).

Figures

Figure 2. Phylogram generated by ML analysis based on combined sequence data of ITS, LSU, rpb 1, rpb 2, mcm 7 and tef 1 a showing phylogenetic relationships within genus Dermoloma. ML bootstrap support values greater or equal to 50 % and Bayesian posterior probabilities greater or equal to 0.90 are indicated above or below the nodes. Sequences originating from type collections are labelled in red and bold.

Figure 4. Heatmap showing clustering based on important morphological differences in Dermoloma (D.) and Neodermoloma (N.). Characters are classified into three categories. Pdia – pileus diameter: 1 = up to 12 mm, 2 = 13–25 mm, 3 = more than 25 mm; Pstr – striation near pileus margin: 1 = none, 2 = indistinct, 3 = distinct; Phyg – pileus hygrophaneity: 1 = none, 2 = indistinct, 3 = distinct; Sthi – stipe thickness: 1 = up to 2 mm, 2 = 2–5 mm, 3 = more than 5 mm; Lnum – number of lamellae near stipe: 1 = up to 20, 2 = 21–30, 3 = more than 30; Lcol – lamellae color: 1 = white to ochraceous-gray, 2 = brownish gray to brownish ochraceous, 3 = brown to dark gray-brown; SPam – spore amyloidity: 1 = inamyloid, 3 = amyloid; SPle – spore length: 1 = up to 5.5 µm, 2 = 5.6–6.5 µm, 3 = more than 6.5 µm; SPwi – spore width: 1 = up to 3.6 µm, 2 = 3.7–4.2 µm, 3 = more than 4.2 µm; SPQ – spore length / width ratio: 1 = less than 1.4, 2 = 1.4–1.6, 3 = more than 1.6; Blen – basidia length: 1 = up to 25 µm, 2 = 26–28 µm, 3 = more than 28 µm; Bwid – basidia width: 1 = less than 6 µm, 2 = 6–6.5 µm, 3 = more than 6.5 µm; MCsh – shape of marginal cells: 1 = cylindrical or clavate and apically obtuse, 2 = lageniform and apically constricted or attenuated, 3 = lobate and diverticulate or branched; Cwid – caulocystidia width: 1 = less than 5.5 µm, 2 = 5.5–8 µm, 3 = more than 8 µm; Csha – shape of caulocystidia: 1 = cylindrical or narrowly clavate and apically obtuse, 2 = broadly clavate or sphaeropedunculate or obpyriform, 3 = lobate or diverticulate or branched.

Figure 35. Basidiomata of Dermoloma in field appearance. a Dermoloma josserandii (SAV F- 20808, epitype), photo S. Jančovičová; b Dermoloma josserandii (SAV F- 20907, epitype), photo V. Shapkin; c Dermoloma magicum (SAV F- 4142, epitype), photo S. Jančovičová; d Dermoloma magicum (SAV F- 20618), photo S. Jančovičová; e Dermoloma murinellum [LIP (PAM 06090203)], photo P. - A. Moreau; f Dermoloma obscurum (SAV F- 20012, holotype), photo S. Jančovičová. Scale bar: 10 mm.

Figure 38. Dermoloma murinellum (ZT Myc 42786, holotype), microscopic elements. a Spores; b caulocystidia; c basidia and basidioles; d marginal cells; e pileipellis elements near the pileus margin; f pileipellis elements near the pileus center. Scale bar: 5 µm for spores and 10 µm for other elements.