Dermoloma fumosidiscum Adamčík & Matheny, 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 fumosidiscum Adamčík & Matheny sp. nov.

Figs 23 c – e , 25

Etymology.

In reference to the dark center of the pileus.

Holotype.

USA • Tennessee, Great Smoky Mountains National Park, Blount Co., Little Pigeon river, right riverbank , elev. 600 m, coord. 35°42'28"N, 83°22'57"E, terrestrial under Acer rubrum , Liliodendron tulipifera , Liquidambar sp. and Quercus sp. , 2 Nov 2013, S. Adamčík (holotype TENN-F-071041 , isotype SAV F-4094 ) .

Diagnosis.

North American species; pilei up to 12 mm, rugulose near center; spores inamyloid.

Pileus 7–12 mm; convex, indistinctly umbonate; margin not striate; surface rough near margin, strongly radially rugulose and veined, hygrophanous; color near margin brownish ochraceous (5 C 3) and with almost white outline, when dry brownish gray (6 C 2) to grayish brown (6 D 3), near center dark brown (6 F 3), when dry grayish brown (6 E 3). Stipe 17–22 × 2 mm; cylindrical, sometimes narrowed towards the base and curved; surface finely longitudinally striate, finely granulose near lamellae, towards the base fibrillose; color near lamellae white, near the base brownish-grayish. Lamellae L = 22–28, l = 1–3; up to 2.5 mm wide; adnate-emarginate and decurrent with tooth; color yellowish gray (4 B 2); edges irregularly serrulate. Context when young elastic, later fragile; odor farinaceous.

Spores (4.8 –) 4.9–5.2 – 5.5 (– 5.8) × (3.5 –) 3.6–3.8 – 4 (– 4.2) μm; ellipsoid, Q = (1.26 –) 1.33–1.38 – 1.43 (– 1.48); walls inamyloid, sometimes thick-walled and dextrinoid; hilar appendage 0.5–1 μm long. Basidia (18 –) 20–22.6 – 25 (– 28) × 5.5–5.9 – 6.5 (– 7) μm; clavate; with 4 sterigmata. Basidioles first cylindrical, then clavate, ca. 3–6.5 μm wide. Marginal cells (11 –) 13.5–16.7 – 20 (– 22) × (4.5 –) 5–5.6 – 6 (– 6.5) μm; similar to basidioles, mainly clavate. Pileipellis 42–52 μm deep; suprapellis 32–38 μm deep, mainly of one layer of densely arranged inflated cells, gradually passing to 15–20 μm deep subpellis of densely packed, intricate, horizontally oriented, 3–10 μm wide hyphae, not sharply delimited from horizontally oriented hyphae in trama; hyphal terminations with brownish yellow parietal pigments, thin-walled or occasionally thickened up to 1 μm, rarely with brownish incrusted pigments near septa of terminal cells. Terminal cells near pileus margin (23 –) 30–38.2 – 46.5 (– 52) × (12 –) 15–19.6 – 24 (– 29) μm; usually sphaeropedunculate, sometimes obpyriform or clavate; subterminal cells usually narrower and implemented in subpellis, often branched, rarely inflated and with lateral swellings. Terminal cells near pileus center (27 –) 33–43.2 – 53 (– 64) × (11 –) 15–18.3 – 22 (– 26) μm; mainly clavate, occasionally obpyriform or sphaeropedunculate, rarely ellipsoid, towards bases occasionally flexuous or lobate; subterminal cells similar to cells near margin. Caulocystidia (13 –) 20.5–28.2 – 36 (– 44) × (3.5 –) 4.5–5.4 – 6.5 (– 8) μm; clavate or subcylindrical, usually not or only slightly flexuous, often individual or in small fascicules, repent or ascending; thin-walled, with yellow parietal pigments and dispersed crystalline or granulose yellow incrustations. Clamp connections present.

Distribution and ecology.

Known from three localities in Smoky Mts., Tennessee, USA; in deciduous forests, two collections from park lawn areas.

Additional material studied.

USA • Tennessee, Great Smoky Mountains National Park, Oak Ridge, Haw Ridge Park , coord. 36°00'38"N, 84°09'46"E, terrestrial under Acer sp. , Carpinus sp. , Cerasus sp. , Liliodendron tulipifera and Quercus sp. , 10 Oct 2021, J. Kalichman JK 079 ( TENN-F-076330 ) ; • Tennessee, Union County, Big Ridge State Park , 36°00'58"N, 83°58'54"E, in yard under hardwoods, Acer sp. , Carya sp. , Cornus sp. , Quercus sp. , 23 Oct 2021, J. Kalichman JK 139 ( TENN-F-076389 ) .

Notes.

Dermoloma fumosidiscum is a North American species with inamyloid spores which belongs to D. subgenus Dermoloma , section Dermoloma . It is sister to the type species of the genus, D. cuneifolium (Fig. 2 ). Unlike European members of section Dermoloma , this species is easily distinguishable by the combination of very small basidiomata and a strongly rugulose pileus center. Fortunately, this allows identification without a microscope, because the species does not have any unique microscopic characters distinguishing it from D. cuneifolium or other similar species. The sequence from the type of D. fumosidiscum was included in the phylogeny by Sánchez-García and Matheny (2017) as Dermoloma sp. and later in Sánchez-García et al. (2021) as “ D. cf. cuneifolium ”.

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 23. Basidiomata of Dermoloma in field appearance. a. Dermoloma curvicystidiatum (CNF 1 / 1963), photo A. Mešić; b. Dermoloma curvicystidiatum (GLM-F 137758), photo A. Karich; c. Dermoloma fumosidiscum (TENN-F- 076389, holotype), photo M. G. Sánchez; d, e Dermoloma fumosidiscum (TENN-F- 076330), photo J. Kalichman; f Dermoloma fuscobrunneum [LIP (PAM 14111008), epitype], photo P. - A. Moreau; g Dermoloma fuscobrunneum (SAV F- 22210), photo S. Jančovičová. Scale bar: 10 mm.

Figure 25. Dermoloma fumosidiscum (SAV F- 4094, isotype), 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.