Dermoloma huartii P. - A. Moreau & Corriol sp. nov.

Figs 31 a, b, 32

Etymology.

Named in honor of the French mycologist Didier Huart, an expert in grassland fungi who provided three collections of this species including the holotype.

Holotype.

France • Pas-de-Calais, Neufchâtel-Hardelot, réserve naturelle du Mont-Saint-Frieux, coord. 50°36'39"N, 01°36'352"E calcareous grassland, 9 Nov 2014, D. Huart and P. - A. Moreau PAM 14110907 (LIP).

Diagnosis.

European species; basidiomata medium to large; pilei 20–30 mm in diameter; stipes usually 2–5 mm wide; lamellae pale ochraceous-gray to white; spores inamyloid, on average longer than 5.5 µm and often wider than 4 µm.

Pileus 20–30 (– 50) mm; convex, soon expanding to plane, sometimes indistinctly umbonate, often lobate; margin usually not striate, indistinctly translucently striate up to half of the radius when wet, recurved when old; surface near margin smooth, sometimes radially rugulose or wrinkled near center, slightly hygrophanous; color when young dark brown (5 F 3, 8 F 5), when mature near margin brown (5 E 4), dark blond (5 D 4), grayish brown (5 D 3), ochraceous-gray (5 B 2, 6 B 2), brownish ochraceous (6 C 3), near center dark brown (5 F 5, 6 F 4), brown (5 E 4). Stipe (22 –) 32–50 (– 70) × 2–5 (– 8) mm; cylindrical, sometimes fusiform, narrowed towards the base, flexuous; surface finely longitudinally striate, granulose or flocculose near lamellae, towards the base finely fibrillose; color near lamellae ochraceous-gray (5 B 2) to almost white, near the base brownish gray (5 C 2) to grayish brown (5 D 3). Lamellae L = (24 –) 26–40 (– 45), l = 1–3 (– 7); 4–6 mm wide; adnate-emarginate and decurrent with tooth; color ochraceous-gray (5 B 2), towards edges almost white; edges slightly irregular. Context when young elastic, later fragile; odor farinaceous.

Spores (5.2 –) 5.6–6.2 – 6.9 (– 8.2) × (3.5 –) 3.9–4.4 – 4.9 (– 5.4) μm; broadly ellipsoid to narrowly ellipsoid, Q = (1.28 –) 1.34–1.42 – 1.50 (– 1.62); walls inamyloid; hilar appendage ca. 1–1.5 μm long. Basidia (19 –) 23–26.4 – 30 (– 36.5) × (4.5 –) 6–6.4 – 7 (– 8) μm; clavate; usually with 2 sterigmata, occasionally with 1, 3 or 4 sterigmata. Basidioles first cylindrical, then clavate, ca. 2–6.5 μm wide. Marginal cells (7.5 –) 11.5–14.2 – 17 (– 19) × (3.5 –) 4–4.6 – 5.5 (– 6) μm; not well-differentiated, cylindrical or clavate, sometimes ellipsoid, often lobate. Pileipellis 57–70 μm deep; suprapellis of one or two layers of inflated cells, gradually passing to 23–33 μm deep subpellis of densely packed, irregularly oriented, puzzled, 3–10 (– 13) μm wide hyphae, not sharply delimited from horizontally oriented hyphae in trama; hyphal terminations with brownish yellow parietal pigments, walls thickened up to 1 (– 1.5) μm and occasionally with yellow-brown incrusted pigments especially near septa of terminal cells and in subpellis. Terminal cells near pileus margin (15.5 –) 32.3–43.6 – 55 (– 85) × (9 –) 14–21.1 – 28 (– 47) μm; usually obpyriform, clavate or sphaeropedunculate, rarely ellipsoid or fusiform; subterminal cells usually narrower and unbranched, clavate or obpyriform, often with lateral swellings. Terminal cells near pileus center (17 –) 32–42.5 – 52.5 (– 71) × (9.5 –) 17–23 – 28.5 (– 37.5) μm; similar to cells near margin but more frequently irregularly lobate; subterminal cells narrower or equally wide, often with lateral swellings or irregularly lobate. Caulocystidia (12.5 –) 25.5–35.7 – 45.8 (– 66) × (2 –) 4–6.1 – 8 (– 11) μm; clavate or cylindrical, often slightly flexuous, sometimes moniliform, often clustered in small ascending fascicules, sometimes individual and repent; usually with slightly thickened walls up to 0.5 μm, often with crystalline or granulose yellow incrustations. Clamp connections present.

Distribution and ecology.

Known from France, Slovakia and Wales (United Kingdom), in semi-natural grasslands on calcareous soil, once also collected in a calcareous beech forest.

Additional material studied.

France • Ariège, Ker de Massat, coord. 42°53'45"N, 01°18'57"E, calcareous beech forest with Buxus sempervirens, 9 Oct 2017, C. Hannoire, CH 17100919 (BBF, as D. cuneifolium); • Pas-de-Calais, Neufchâtel-Hardelot, réserve naturelle du Mont-Saint-Frieux, coord. 50°36'39"N, 01°36'35"E, calcareous semi-natural grassland, 9 Nov 2014, D. Huart and P. - A. Moreau PAM 14110904 (LIP); • ibid., 9 Nov 2014, D. Huart and P. - A. Moreau PAM 14110909 (LIP). Slovakia • Strážovské vrchy Mts., motocross area 1 km W of Čelkova Lehota, elev. 460 m, 49°00'55"N, 18°31'12"E, grassland dominated by Dactylis glomerata and Trifolium arvense, 6 Oct 2005, V. Kučera (SAV F-4149). United Kingdom • Wales, Powis Castle gardens, coord. 52°38'58"N, 03°09'34"E, terrestrial in lawn, 22 Oct 2014, D. Harries (SAV F-4378).

Notes.

With inamyloid spores, D. huartii belongs to D. subgenus Dermoloma, section Dermoloma, and is closely related to type of the genus D. cuneifolium (Fig. 2). All species in the section are very similar and their identification requires special attention (see notes under D. cuneifolium). Dermoloma huartii is a medium-sized species that can be distinguished from D. cuneifolium by the spores longer than 5.5 μm and from the other large-capped species of the section by the stipe up to 5 mm wide. This species was included in the phylogenetic study by Sánchez-García et al. (2021) as “ D. cf. cuneifolium ”.