Dermoloma obscurum Caboň & Jančovič., 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 obscurum Caboň & Jančovič. sp. nov.

Figs 35 f , 39 a , 40

Etymology.

In reference to the basidiomata with dark colors, especially on the lamellae.

Holotype.

Italy • Toscana, 1.3 km SE of Frassine , elev. 260–270 m, coord. 43°06'15"N, 10°46'45"E, terrestrial, wooded pasture, 10 Nov 2016, S. Adamčík ( SAV F-20012 ).

Diagnosis.

European species; basidiomata small, dark, gray and brown colored; pilei 7–12 mm in diameter; stipes 1–2 mm wide; lamellae brown to dark brown when young and fresh, pallescent with drying; spores amyloid, broadly ellipsoid to ellipsoid, 5.4–6.4 × 4.2–4.8 μm; caulocystidia up to 6.5 μm wide, clavate or cylindrical.

Pileus (4 –) 7–12 (– 18) mm; young semiglobose, mature convex, expanding to plane, rarely lobate; margin translucently striate to half of the radius when wet; surface smooth, sometimes rugulose or rough near center, hygrophanous; color when young dark brown (7 F 3), when mature near margin dark brown (6 F 4, 6 F 5), grayish brown (6 E 3), when dry brown (6 E 4), grayish brown (6 E 3) to ochraceous-gray (6 D 2), near center dark brown (6 F 3, 6 F 4, 6 F 5) to almost black, when dry dark brown (6 F 4), brown (6 E 4) to grayish brown (5 D 3). Stipe (15 –) 20–33 (– 45) × 1–2 mm; cylindrical, sometimes narrowed towards the base, flexuous; surface indistinctly longitudinally striate, when young pruinose, later towards the base or completely smooth and shiny; color near lamellae brownish gray (6 E 2), grayish brown (6 D 3,6E 3) to dark brown (6 F 3, 6 F 4), near the base dark brown (6 F 4, 6 F 5, 7 F 5) to black. Lamellae L = (14 –) 17–22, l = (0 –) 1–3; 2–3 mm wide; adnate-emarginate and sometimes decurrent with tooth; color brown (6 E 3) to dark brown (6 F 3, 6 F 2), when old and dry ochraceous-gray (6 C 2) to yellowish gray (4 B 2); edges entire. Context when young elastic, later fragile; odor farinaceous.

Spores (4.9 –) 5.4–5.9 – 6.4 (– 7.3) × (3.7 –) 4.2–4.5 – 4.8 (– 5.3) μm; broadly ellipsoid to ellipsoid, Q = (1.12 –) 1.20–1.31 – 1.42 (– 1.66); walls amyloid, sometimes thick-walled and dextrinoid; hilar appendage ca. 0.5–1.5 μm long. Basidia (20 –) 23.5–26.6 – 30 (– 39.5) × (4.5 –) 6–6.4 – 7 (– 8) μm; clavate; usually with 4 sterigmata, sometimes with both, 4 and 2 sterigmata, one collection ( SAV F-20012 ) with only 2 sterigmata. Basidioles first cylindrical, then clavate, ca. 2–6.5 μm wide. Marginal cells (12 –) 14–19.7 – 29 (– 47) × (3.5 –) 4.5–6.4 – 8 (– 12) μm; not well-differentiated, clavate, rarely cylindrical. Pileipellis 70–85 μm deep; suprapellis 40–50 μm deep, of mainly one or two layers of inflated, densely arranged cells; subpellis well-differentiated, 30–45 μm deep, of densely packed, irregularly oriented, puzzled, 3–10 (– 15) μm wide hyphae gradually passing to horizontally oriented hyphae in trama; hyphal terminations with brownish yellow parietal pigments, locally also with brown incrusted pigments, usually with thick walls up to 1 μm, near septa of terminal cells and in upper part of subpellis with more thickened walls up to 2 μm. Terminal cells near pileus margin (15 –) 25.5–36.2 – 47 (– 82) × (6.5 –) 13–18.2 – 23.5 (– 31) μm; usually obpyriform or clavate, sometimes sphaeropedunculate, rarely lageniform, ellipsoid or subglobose; subterminal cells usually narrower and subcylindrical, occasionally inflated and fusiform, often branched. Terminal cells near pileus center (17 –) 26–36.6 – 46.9 (– 73) × (8 –) 12.5–17.9 – 23 (– 33.5) μm; similar to cells near margin; subterminal cells similar to cells near margin. Caulocystidia (15 –) 21–34.3 – 47.5 (– 70) × (2 –) 3.5–5.1 – 6.5 (– 9) μm; clavate or cylindrical, usually not or only slightly flexuous, repent, dispersed, individual or in small fascicules; often with slightly thickened walls up to 0.5 μm especially near septa, hyaline. Clamp connections present.

Distribution and ecology.

Known from Croatia, France, Germany, Italy, The Netherlands and Slovakia; in semi-natural grasslands on calcareous soil.

Additional material studied.

Croatia • 1.2 km NE of Gornja Supetarska Draga, Rab island, pasture with sheep , coord. 44°48'01"N, 14°44'40"E, edge of Pinus halepensis and Quercus ilex forest, 7 Oct 2007, M. Čerkez ( CNF 1/4830 ) . France • Tarn-et-Garonne, military camp of Caylus , coord. 44°18'53"N, 01°43'47"E, calcareous dry semi-natural grassland, 14 Oct 2013, C. Hannoire CH 13101428 ( BBF, as D. phaeopodium ) . Germany • Rheinland-Pfalz, Heimberg , elev. 265 m, coord. 49°48'37"N, 07°44'06"E, terrestrial in semi-natural grassland, 10 Nov 2019, S. Adamčík ( SAV F-20549 ) ; • ibid., 10 Nov 2019, F. Hampe ( SAV F-20553 ) ; • Rheinland-Pfalz, Horbach , elev. 370 m, coord. 49°49'45"N, 07°31'17"E, terrestrial in semi-natural grassland, 8 Nov 2019, S. Adamčík ( SAV F-20519 ) . Italy • Toscana, 1.3 km SE of Frassine , elev. 260–270 m, coord. 43°06'15"N, 10°46'45"E, terrestrial, wooded pasture, 10 Nov 2016, M. Caboň ( SAV F-20013 ) . The Netherlands • Pfalz, Duitsland, Ebenberg , poor grassland, 2 Oct 2013, E. Arnolds Arnolds 13-21 ( L, as D. phaeopodium ) . Slovakia • Biele Karpaty Mts., 1.5 km E of Nová Bošáca, Blažejová Natural Monument , elev. 415 m, coord. 48°52'33.3"N, 17°49'03.4"E, terrestrial among grass, 30 Jul 2005, V. Kautman ( SAV F-4144 ) .

Notes.

Dermoloma obscurum belongs to D. subgenus Amylospora , section Atrobrunnea . It has small mycenoid basidiomata and typically very dark gray to black colors with few brown components which distinguishes it from similar Dermoloma species. It forms a well-supported clade with other species with small basidiomata described or collected from the Mediterranean area, including D. pusillum , D. clavicystis and an unnamed Dermoloma species (Fig. 2 ). From the two described species it differs by the narrower caulocystidia. Unlike other closely related species, D. obscurum was collected both in the Mediterranean and temperate areas of Central Europe. The species was included in the phylogenetic study by Sánchez-García et al. (2021) as “ D. cf. pusillum ”.

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 35. Basidiomata of Dermoloma in field appearance. a Dermoloma josserandii (SAV F- 20808, epitype), photo S. Jančovičová; b Dermoloma josserandii (SAV F- 20907, epitype), photo V. Shapkin; c Dermoloma magicum (SAV F- 4142, epitype), photo S. Jančovičová; d Dermoloma magicum (SAV F- 20618), photo S. Jančovičová; e Dermoloma murinellum [LIP (PAM 06090203)], photo P. - A. Moreau; f Dermoloma obscurum (SAV F- 20012, holotype), photo S. Jančovičová. Scale bar: 10 mm.

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 40. Dermoloma obscurum (SAV F- 20013), 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.