Dermoloma applanatum Corriol & P. - A. Moreau, 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 applanatum Corriol & P. - A. Moreau sp. nov.

Figs 10 d, e , 13

Etymology.

The epithet applanatum refers to the characteristic applanate shape of the pileus.

Holotype.

United Kingdom • Wales, Pembrokeshire, Upton Castle , coord. 51°42'22"N, 04°51'57"E, terrestrial in lawn, 26 Oct 2014, S. Adamčík ( SAV F-4415 ).

Diagnosis.

European species; basidiomata moderately large; pilei soon expanding to plane; stipes 2–5.5 mm wide, fusiform and dark brown near bases; spores amyloid, ellipsoid to oblong; caulocystidia 3.5–5.5 μm wide.

Pileus 10–30 (– 40) mm; convex, soon expanding to plane, sometimes lobate; margin translucently striate to half of the radius or not striate, recurved when old; surface smooth near margin, rugulose and sometimes pitted near center, hygrophanous; color near margin dark brown (6 F 4, 6 F 5), brown (5 E 4,6E 4), grayish brown (5 E 3, 6 D 3,6E 3), when dry brownish ochraceous (5 C 3) or grayish brown (5 D 4, 6 D 4), near center dark brown (6 F 3, 6 F 4, 6 F 5) or brown (6 E 5), when dry light brown (5 D 4, 5 D 5, 6 D 4). Stipe (20 –) 22–37 (– 40) × (1.5 –) 2–5.5 (– 8) mm; fusiform or cylindrical, narrowed towards the base, flexuous; surface finely longitudinally striate, near lamellae pruinose or granulose, towards the base finely fibrillose or squamulose; color near lamellae when young pale gray (B 1, C 1), ochraceous-gray (5 B 2), when mature brownish gray (5 C 2, 5 C 2, 6 C 2, 6 D 2) or grayish brown (5 D 3, 6 D 3), near the base brownish gray (6 C 2, 6 D 2), grayish brown (6 D 3,6E 3), brown (6 E 4, 7 F 3, 7 F 4) to almost black (7 F 8). Lamellae L = 20–39 (– 48), l = (0 –) 1–3; 4–8 mm wide; adnate-emarginate and decurrent with tooth; color ochraceous-gray (6 B 2), brownish gray (5 D 2, 6 C 2, 6 D 2), grayish brown (7 D 3), towards edges paler ochraceous-gray (5 B 2), brownish gray (5 C 2); edges entire. Context when young compact, later fragile; odor farinaceous.

Spores (3.6 –) 5.2–6 – 6.9 (– 8.4) × (3.1 –) 3.5–3.7 – 4 (– 4.3) μm; ellipsoid to oblong, Q = (1.26 –) 1.44–1.63 – 1.81 (– 2.03); amyloid; hilar appendage 0.5–1.5 μm long. Basidia (19.5 –) 23.5–28.3 – 33 (– 42) × (5 –) 5.5–6.2 – 7 (– 8) μm; clavate; with 4 sterigmata. Basidioles first cylindrical, then clavate, ca. 3–6 μm wide. Marginal cells (11 –) 16.5–23.1 – 29.5 (– 47) × (3 –) 6–8 – 10 (– 12) μm; clavate, sometimes apically constricted, rarely lobate. Pileipellis 70–85 μm deep; suprapellis mainly of two, occasionally one or three layers of inflated cells; subpellis 28–40 μm deep, well defined, of densely packed, irregularly oriented, intricate, 39 (– 15) μm wide hyphae, not sharply delimited from horizontally oriented hyphae in trama; hyphal terminations with brownish parietal pigments, hyphae in subpellis thickened up to 1 μm and locally with dark incrusted pigments. Terminal cells near pileus margin (18.5 –) 29.5–40.6 – 51.7 (– 80) × (8 –) 13–20 – 27 (– 43) μm; usually clavate, sphaeropedunculate or obpyriform, sometimes ellipsoid, towards septa occasionally flexuous or constricted; subterminal cells usually narrower, cylindrical or similar to terminal cells and clavate or obpyriform, occasionally with lateral swellings, usually not branched and not lobate. Terminal cells near pileus center (12.5 –) 26.5–37.6 – 49 (– 77) × (6 –) 11.5–18 – 24.5 (– 39) μm; similar to cells near margin; subterminal cells mainly narrower and cylindrical or clavate, occasionally with lateral swellings, not lobate, occasionally branched. Caulocystidia (19 –) 26.5–34.8 – 43 (– 57) × (2.5 –) 3.5–4.4 – 5.5 (– 7.5) μm; clavate, sometimes cylindrical or capitate, slightly flexuous, rarely apically constricted, often clustered in small ascending fascicules, sometimes individual and repent; usually with slightly thickened walls up to 0.5 μm, with yellowish parietal pigments. Clamp connections present.

Distribution and ecology.

Known from France, Germany and Wales ( United Kingdom); in semi-natural grassland and (rarely) forests, on neutral to calcareous loamy soil.

Additional material studied.

France • Hautes-Pyrénées, Castet de Gerde , coord. 43°03'35"N, 00°09'54"E, mown meadow on neutral clay soil, 14 Nov 2010, G. Corriol GC 10111408 ( BBF) ; • Pas-de-Calais, Baincthun, forêt domaniale de Boulogne-sur-Mer, maison forestière de Wirwignes , coord. 50°40'55"N, 01°44'26"E, on clay-calcareous ground under Carpinus betulus and Quercus petraea , 14 Sep 2014, E. Bastien PAM 14091410 ( LIP) . Germany • Baden-Württemberg, Justingen, Schachenheide , coord. 48°24'35"N, 09°40'25"E, terrestrial in grassland, 2 Oct 2021, S. Adamčík ( SAV F-20860 ) ; • Rheinland-Pfalz, Sobernheim , elev. 215 m, coord. 49°47'18"N, 07°40'35"E, terrestrial in semi-natural grassland, 9 Nov 2019, C. Manz ( SAV F-20525 ) . United Kingdom • Wales, Pembrokeshire, Upton Castle , coord. 51°42'22"N, 04°51'57"E, terrestrial in lawn, 26 Oct 2014, D. Harries ( SAV F-4419 ) ; • Wales, Powis Castle gardens , coord. 52°38'58"N, 03°09'34"E, terrestrial in lawn, 22 Oct 2014, D. Harries ( SAV F-4379 ) .

Notes.

Dermoloma applanatum is a member of D. subgenus Amylospora , section Atrobrunnea (Fig. 2 ). In the field it is relatively well defined by a collybioid habit, typical plane pilei when mature and relatively dark colors. Similar species with collyboid basidiomata have caulocystidia wider than 5 μm. The most closely related D. angustisporum has much smaller mycenoid basidiomata (see above). This species was previously included in the phylogenetic study by Sánchez-García et al. (2021) as “ D. phaeopodium like ”. The majority of our collections were associated with multiple Dermoloma species, but not always on sites with an apparent conservation concern (collections from Wales in castle gardens).

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 10. Basidiomata of Dermoloma in field appearance. a Dermoloma angustisporum (SAV F- 20343, holotype), photo S. Jančovičová; b, c Dermoloma appalachianum (TENN-F- 076604), photo D. Grootmyers; d Dermoloma applanatum (SAV F- 4415, holotype), photo D. Harries; e Dermoloma applanatum (SAV F- 4419), photo D. Harries; f Dermoloma atrocinereum [BBF (GC 16112316)], photo G. Corriol; g Dermoloma atrocinereum (SAV F- 20523), photo S. Jančovičová. Scale bar: 10 mm.

Figure 13. Dermoloma applanatum (SAV F- 4415, 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.