Dermoloma parvisporum Adamčík & Dima, 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 parvisporum Adamčík & Dima sp. nov.

Figs 39 b , 41

Etymology.

Referring to the small spores.

Holotype.

Slovakia • Poloniny Mts., 4 km N of Stakčín, pastures above the water reservoir Starina , elev. 380–420 m, coord. 49°02'43"N, 22°14'56"E, terrestrial among grass, 25 Sep 2017, S. Adamčík ( SAV F-20229 ).

Diagnosis.

European species; basidiomata small, mycenoid; pilei 6–8 mm in diameter, not striate near margin; stipes up to 1.5 mm wide; lamellae brown to dark brown; spores amyloid, small, 4.8–5.4 × 3.5–4 μm; marginal cells with attenuated, long, flexuous terminal parts; caulocystidia 8.5–13.5 μm wide, clavate, obpyriform, sphaeropedunculate, flexuous, nodulose-lobate.

Pileus 6–8 mm; convex, sometimes indistinctly umbonate; margin not striate; surface smooth, matt, pruinose; color near margin dark brown (paler than 6 F 6), near center dark brown to black (7 F 4). Stipe 24–33 × 0.75–1.25 mm; cylindrical, flexuous especially near the base; surface finely longitudinally striate, near lamellae finely pruinose, bellow glabrous; color near lamellae brown (7 E 3,7E 4) to dark brown (7 F 5), near the base dark brown (7 F 5). Lamellae L = 17–25, l = 1–3; up to 1.5 mm wide; adnate; color brown (7 E 3) to dark brown (paler than 7 F 3); edges entire. Context fragile; odor indistinct.

Spores (4.6 –) 4.8–5.1 – 5.4 (– 5.8) × (3.3 –) 3.5–3.8 – 4 (– 4.1) μm; broadly ellipsoid to ellipsoid, Q = (1.17 –) 1.29–1.36 – 1.44 (– 1.51); walls amyloid; hilar appendage ca. 0.5–1 μm long. Basidia (23 –) 25–26.6 – 28 (– 30) × (5.5 –) 6–6.2 – 6.5 (– 7) μm; clavate; mainly with 4, rarely with 2 sterigmata. Basidioles first cylindrical, then clavate, ca. 3–5.5 μm wide. Marginal cells (26 –) 27.5–36.4 – 45 (– 52) × 3.5–3.9 – 4.5 (– 5) μm; attenuated, with wider base, at apex with long, narrow (1.5–2 μm), flexuous or twisted, nodulose, intermingled or diverticulate projections, often with attached loose spores. Pileipellis 55–75 μm deep; suprapellis 35–45 μm deep, usually of one or two layers of inflated, densely arranged cells, subpellis not well differentiated, 20–30 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 and in subpellis with dark brown to black parietal and locally also incrusted pigments, walls only slightly thickened up to 0.5 μm especially in subpellis. Terminal cells near pileus margin (16 –) 20–27.8 – 35.5 (– 54) × (9.5 –) 12–15 – 18 (– 23) μm; sphaeropedunculate, obpyriform clavate or subglobose; subterminal cells usually narrower and rarely branched, fusiform-ventricose, sometimes with lateral swellings or lobate. Terminal cells near pileus center (15.5 –) 25–38.1 – 51.5 (– 68) × (9 –) 13.5–18.5 – 23.5 (– 32) μm; usually obpyriform or clavate, rarely sphaeropedunculate; subterminal cells usually narrower, usually narrowly fusiform or subcylindrical, often branched. Caulocystidia (19 –) 23–31.2 – 39.3 (– 52) × (6.5 –) 8.5–11 – 13.5 (– 18.5) μm; clavate, obpyriform, sphaeropedunculate, flexuous, nodulose-lobate, often clustered in small ascending fascicules, sometimes individual and repent; thin-walled, with faint brownish parietal pigments. Clamp connections present.

Distribution and ecology.

Known from two localities in Norway and Slovakia; in semi-natural or natural, dry grasslands; habitat preferences insufficiently known.

Additional material studied.

Norway • Oslo, Gressholmen , coord. 59°53'01"N, 10°43'16"E, in dry, natural, calcareous grassland, 7 Oct 2013, A. Molia and T. Læssøe NOBAS 2937-16 ( O-F-21841 ) .

Notes.

Dermoloma parvisporum belongs to D. subgenus Amylospora , section Atrobrunnea . It is easily distinguishable from similar species with small basidiomata due to its very small spores and marginal cells with attenuated and flexuous terminations that are often intermingled because of multiple projections that trap loose spores from the hymenium. We did not observe this in other Dermoloma species, but the phenomenon may be also present in species with projections on marginal cells like D. pruinosipes .

Figures

Figure 39. Basidiomata of Dermoloma in field appearance. a Dermoloma obscurum (SAV F- 20553), photo S. Jančovičová; b Dermoloma parvisporum (SAV F- 20229, holotype), photo S. Jančovičová; c Dermoloma phaeopodium (SAV F- 20546), S. Jančovičová; d Dermoloma phaeopodium (SAV F- 22208), photo S. Jančovičová; e Dermoloma pruinosipes (SAV F- 20834, holotype), photo S. Jančovičová; f Dermoloma pruinosipes (SAV F- 20504), photo S. Jančovičová. Scale bar: 10 mm.

Figure 41. Dermoloma parvisporum (SAV F- 20229, holotype), microscopic elements. a Spores; b caulocystidia; c basidia and basidioles; d pileipellis elements near the pileus margin; e pileipellis elements near the pileus center. Scale bar: 5 µm for spores and 10 µm for other elements.