Dermoloma appalachianum 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 appalachianum Adamčík & Matheny sp. nov.

Figs 10 b, c , 12

Etymology.

Type collected in the Appalachian Mts. of Tennessee, USA.

Holotype.

USA • Tennessee, Sevier County, Gatlinburg , on acidic soil in mixed forest including Quercus , Carpinus , Tsuga , 10 Jun 2010, J. M. Birkebak JMB 10061007 ( TENN-F-065390 ) .

Diagnosis.

North American species with small basidiomata and amyloid spores on average longer than 7 μm.

Pileus 7–13 mm; convex, soon expanding to plane to slightly centrally depressed, indistinctly umbonate; margin even or striate up to 2 mm; surface slightly to strongly radially wrinkled, hygrophanous; color near margin brownish gray (5 C 2) to brownish ochraceous (5 C 3), near center dark brown (6 F 6), when dry fading to brownish gray (6 C 2) or grayish brown (6 D 3) at the margin and grayish brown (6 E 3) at the center. Stipe 17–22 × 2 mm; cylindrical, equal or tapering toward the base, at times curved; surface near lamellae slightly fibrillose-granulose, towards the base finely longitudinally striate-fibrillose; color near lamellae almost white, near the base brownish ochraceous (5 C 3) to brownish gray. Lamellae L = 22–28, l = 1–3; up to 2.5 mm wide; adnate to uncinate, slightly intervenose; color white to yellowish gray (4 B 2); edges even. Context when young elastic, later fragile; odor farinaceous.

Spores (6.1 –) 6.7–7.4 – 8.2 (– 9.3) × (3.6 –) 4.1–4.5 – 4.9 (– 5.2) μm; narrowly ellipsoid to oblong, sometimes slightly amygdaloid, Q = (1.43 –) 1.53–1.64 – 1.75 (– 1.94); walls amyloid; hilar appendage 0.5–1 μm long. Basidia (25 –) 26–27.9 – 29.5 (– 31) × (7 –) 7.5–7.9 – 8.5 (– 9) μm; clavate; mainly with 4 sterigmata, rarely 1–2 sterigmata. Basidioles first cylindrical, then clavate, ca. 3.5–7 μm wide. Marginal cells (11 –) 14.5–19.7 – 24.5 (– 28) × (5 –) 6–7.3 – 8.5 (– 10) μm; clavate or capitate, often pedunculate, occasionally lobate or diverticulate, apically obtuse, subterminal cells often with lateral branches or swellings. Pileipellis 70–85 μm deep; suprapellis 40–50 μm deep, usually of one or two layers of inflated, densely arranged cells; subpellis 34–38 μm deep, of densely packed, irregularly oriented, 4–8 (– 15) μm wide hyphae, not sharply delimited from horizontally oriented hyphae in trama; hyphal terminations with brownish yellow parietal pigments, in subpellis darker yellow brown and near center also incrusted pigments, walls thickened up to 0.5 μm, near septa of terminal cells and in subpellis up to 1 μm. Terminal cells near pileus margin (25 –) 28.5–37.2 – 45.5 (– 66) × (11 –) 14–16.8 – 19.5 (– 25) μm; usually clavate, sphaeropedunculate or obpyriform, sometimes with narrowed, flexuous or lobate basal part; subterminal cells mainly branched, usually not inflated, fusiform, flexuous, often with branches or nodulose, occasionally inflated and with lateral swellings. Terminal cells near pileus center (18 –) 22.5–33.3 – 44 (– 57) × (8.5 –) 10–15.6 – 21 (– 28) μm; clavate, obpyriform, sphaeropedunculate, subglobose or ellipsoid, near basal parts often flexuous, lobate or with lateral swellings; subterminal cells similar to cells near margin. Caulocystidia (27 –) 35.5–49 – 62 (– 72) × 3.5–4.8 – 6 (– 8.5) μm; mainly narrowly clavate, flexuous, often twisted, apically mainly obtuse but often also constricted, rarely lobate, completely covering surface of stipe but loosely arranged, often intricate, repent or with ascending apices; thin-walled, with brownish yellow parietal pigments, occasionally partially with loose yellowish incrustations. Clamp connections present.

Distribution and ecology.

Known from two localities in the Great Smoky Mountains, Tennessee, USA; in temperate, mixed deciduous forest.

Additional material studied.

USA • Tennessee, Cocke Co., Great Smoky Mountains National Park, Cosby Campground , elev. 625 m, coord. 35°45'22"N, 83°12'27"E, on acidic soil near Acer sp. , Carpinus caroliniana , Carya sp. , Liriodendron tulipifera , Magnolia acuminata , M. tripetala , Oxydendron arboreum , Quercus sect. Lobatae , Rhododendron sp. , Tilia americana and Tsuga canadensis , 29 Aug 2021, J. Kalichman and D. Grootmyers DG 21082913 ( TENN-F-076604 ) .

Notes.

Dermoloma appalachianum is a member of D. subgenus Amylospora , section Atrobrunnea . The lengthy spores (on average longer than 7 μm), in combination with the small mycenoid basidiomata, clearly distinguish this North American species from other similar European species. It is member of a distinct clade which includes D. josserandii and other taxa with relatively sturdy collybioid and pale colored basidiomata (Fig. 2 ). The North American species D. vellingae and D. hymenocephalum are also members of this clade but they both differ by shorter spores. This species was included in the phylogenetic study by Sánchez-García et al. (2021) as “ Dermoloma sp. 10 ”. The collection TENN-F-065390 is selected as holotype because it contains multiple basidiomata but unfortunately it was not photographed.

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 12. Dermoloma appalachianum (TENN-F- 065390, 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.