Dermoloma compactum Friebes & Karich, 2025

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 compactum Friebes & Karich sp. nov.

Figs 15 e, f , 19

Etymology.

Basidiomata are bulky and short.

Holotype.

Slovenia • Zgornje Gorje, Goreljek, slope next to Šport Hotel Pokljuka , elev. 1260 m, coord. 46°20'15"N, 13°57'40"E, soil among moss and grass, 10 Oct 2021, G. Friebes GF 20211010 ( SAV F-23421 ).

Diagnosis.

European species; basidiomata relatively robust but medium to small; pilei usually up to 25 mm in diameter, brown to dark brown; stipe 3–6 mm wide with brown fibrils or squamules; spores amyloid, on average ca. 4.2 µm wide.

Pileus 10–21 (– 30) mm; convex to almost plane, broadly conical; margin not striate, deflexed; surface finely rough to almost smooth near margin, distinctly radially rugulose near center, sometimes pruinose, hygrophanous and discoloring first in center; color near margin brown (5 E 4, 5 F 5,5E 7,6E 4,7E 5) to dark brown (6 F 4), when dry brown (6 E 5), dark blond (5 D 4) to grayish brown (5 D 3), near center dark brown (6 F 4), when dry brown (5 E 5, 5 F 7,6E 7) to light brown (5 D 4, 5 D 5). Stipe (16 –) 21–40 × 3–6 (– 9) mm; usually fusiform, sometimes cylindrical or flexuous, narrowed towards the base; surface pruinose near lamellae, towards the base fibrillose-squamulose; color near lamellae yellowish white (4 A 2) to ochraceous-gray (paler than 5 B 2), towards the base grayish ochraceous (paler than 5 B 3) to light brown (5 D 4), with darker fibrils or squamules (dark brown 5 F 5, 5 F 7). Lamellae L = 22–36, l = (1 –) 3; up to 4 mm wide; adnexed to adnate-emarginate; color ochraceous-gray (5 B 2) to brownish ochraceous (5 C 3); edges entire. Context when young compact, later in pileus fragile; odor farinaceous.

Spores (5.5 –) 5.8–6.2 – 6.8 (– 7.4) × (3.6 –) 3.9–4.2 – 4.5 (– 5.1) μm; ellipsoid, Q = (1.26 –) 1.41–1.5 – 1.6 (– 1.67); walls amyloid, thin-walled; hilar appendage ca. 0.5–1.5 μm long. Basidia (23 –) 26–30.4 – 35 (– 41) × (5 –) 6–6.6 – 7 (– 8) μm; clavate; mainly with 4 sterigmata, occasionally with 2 sterigmata, rarely 1 sterigma. Basidioles first cylindrical, then clavate, ca. 3–6.5 μm wide. Marginal cells (8 –) 13–18.9 – 24 (– 30) × (3 –) 4.5–6.1 – 8 (– 10) μm; not well-differentiated, clavate, occasionally lobate or flexuous, rarely bifurcate. Pileipellis 75–95 μm deep; suprapellis 40–47 μm deep, usually of one or two layers of inflated, densely arranged cells; subpellis well-differentiated, 30–50 μm deep, of densely packed, mainly horizontally oriented, intricate, 3–10 μm wide hyphae, gradually passing to horizontally oriented hyphae in trama; hyphal terminations with brownish parietal pigments, near septa of terminal cells with dark brown parietal and locally also finely incrusted pigments, walls thickened especially in subpellis up to 1 μm. Terminal cells near pileus margin (12 –) 24–34.5 – 46 (– 55) × (8 –) 11–16.2 – 21 (– 36) μm; sphaeropedunculate or clavate, rarely obpyriform; subterminal cells mainly narrowly cylindrical, occasionally inflated and clavate, often flexuous, nodulose or with lateral swellings, occasionally branched. Terminal cells near pileus center (18 –) 24–34.4 – 46 (– 59) × (8 –) 10–14.9 – 20 (– 26) μm; mainly clavate and less frequently sphaeropedunculate, occasionally flexuous, nodulose or lobate; subterminal cells mainly narrower and subcylindrical, usually flexuous and lobate or with lateral swellings, occasionally branched. Caulocystidia (14 –) 19–31.5 – 46 (– 82) × (4 –) 5–7.1 – 9 (– 15) μm; mainly cylindrical and flexuous, occasionally obpyriform, clavate or sphaeropedundulate, occasionally lobate or nodulose, clustered in repent or ascending fascicules; usually with slightly thickened walls up to 0.5 μm, near septa with brownish parietal pigments. Clamp connections present.

Distribution and ecology.

Known from France, Germany, Slovakia, Slovenia and Wales ( United Kingdom); in semi-natural grassland on neutral to alkaline soil.

Additional material studied.

France • Pyrénées-Atlantiques, Portalet , coord. 42°48'59.7"N, 00°24'53.74"E, terrestrial on pasture, 7 Oct 2022, M. Caboň ( SAV F-22285 ) . Germany • Sachsen, Adorf, NSG Zeidelweide , coord. 50°18'01.22"N, 12°13'17"E, regularly mowed semi-natural grassland, 23 Sep 2022, A. Karich and R. Ullrich IHI- 22 Der 01 ( GLM-F 137756 , as D. cf. pseudocuneifolium ) . Slovakia • Kremnické vrchy Mts., 3 km W of Tajov , elev. 710 m, coord. 48°44'53"N, 19°01'35"E, terrestrial in extensively grazed pasture, 24 Oct 2020, V. Shapkin ( SAV F-20794 ) ; • Podbeskydská vrchovina Mts., 1.5 km SW of Beňadovo, Beňadovské rašelinisko , elev. 720–750 m, coord. 49°25'16"N, 19°19'55"E, terrestrial on meadow, 10 Oct 2012, S. Adamčík ( SAV F-3838 ) . United Kingdom • Wales, Graig, Llanymddyfri , coord. 51°58'41"N, 03°42'51"E, 24 Sep 2021, G. Griffith DM 0921 ( ABS, as D. magicum ) .

Notes.

Dermoloma compactum is a member of D. subgenus Amylospora , section Atrobrunnea . It shares a distinctive morphology with two other related European species, D. josserandii and D. pseudojosserandii , as their basidiomata are also sturdy and reminiscent of small individuals of Tricholoma , but the pileus size is relatively small. They form a well-supported clade together with two additional North American species (Fig. 2 ). Dermoloma compactum can be distinguished in the field from D. josserandii and D. pseudojosserandii by the darker brown pilei and stipes with distinct brown fibrils toward the base. In addition, it differs by narrower spores (on average ca. 4.2 μm). This species was included in the phylogenetic study by Sánchez-García et al. (2021) as “ Dermoloma sp. 11 ”.

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 15. Basidiomata of Dermoloma in field appearance. a Dermoloma bellerianum (SAV F- 4416, epitype), photo D. Harries; b Dermoloma bellerianum [LIP (PAM 05100303)], photo P. - A. Moreau; c Dermoloma carpathicum (SAV F- 4268), photo S. Jančovičová; d Dermoloma carpathicum (SAV F- 20805), photo S. Jančovičová; e Dermoloma compactum (SAV F- 23421), holotype, photo G. Friebes; f, g Dermoloma compactum (SAV F- 20794), photo S. Jančovičová. Scale bar: 10 mm.

Figure 19. Dermoloma compactum (SAV F- 3838), 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.