Gymnopus wutaishanensis L. Fan & N. Mao 2022, sp. nov.

Gymnopus wutaishanensis L. Fan & N. Mao, sp. nov. (Figs. 3, 4)

Mycobank:—MB841244

Diagnosis:—It is distinguished from phylogenetically closest species G. densilamellatus and G. polyphyllus by its tangy odor and stipe covered with white hairs; morphologically, it differ from other species in Gymnopus by its unpleasant favour of basidiomata, pale orange to pinkish brown pileus, crowded lamellae, stipe covered with white hairs, and ellipsoid to narrowly ellipsoid basidiospores.

Etymology:—‘ wutaishanensis’, Wutaishan Moutains, refers to the type locality.

Holotype:— CHINA. Shanxi province, Wutai county, Wutaishan Mountains, 38°57’9’’N, 113°30’9’’E, 2070 m elev., 23 July 2019, on the ground in coniferous forest dominated by Larix principis-rupprechtii Mayr., Y.Y. Xu (BJTC FM484!, holotype).

Description:— Basidiomata single or in groups. Pileus 10–60 mm diam, low convex to plane convex when young, then plane to slightly depressed center, not translucently striate or sometimes with fine striate at the margin only, margin cracking with age, surface smooth or radially rugulose, pale orange (#e19e87) to pinkish brown (#cc8263), centre dark orange (#a64929) to brown (#924024). Lamellae close, L = 70–80, l = 1–2, adnate, white (#ffffff); edge smooth, lamellulae concolorous with lamellae. Stipe 30–60 × 2–5 mm, cylindrical or laterally compressed, hollow, equal or sometimes slightly broadened at base, light gray (#cccccc) to pale white (#f7f7f7), sometimes dark grayish orange (#8f857b) at apex when old, surface often densely covered with white hairs. Context concolorous with lamellae. Odor tangy and unpleasant. Taste not recorded.

Basidiospores [25/3/3] (4–)5–6(–7) × (2–)2.5–4 μm; [Q = (1.50–)1.67–2.05(–2.22), avQ = 1.82 ± 0.23]; ellipsoid to narrowly ellipsoid, smooth, hyaline, thin-walled. Basidia 25–35 × 5–8 μm, clavate, hyaline, with four sterigmata. Cheilocystidia numerous, 18–40(–60) × 3–7 μm, variable in shape, cylindrical, clavate, mostly irregular, rostrate, or coralloid at apex, hyaline, thin-walled. Pleurocystidia absent. Lamellar trama regular, made of cylindrical or subinflated 2–9 μm, hyaline, thin-walled hyphae. Pileipellis a cutis composed of cylindrical, 3–10 μm, brownish or hyaline, thinto slightly thick- walled hyphae; terminal cells and lateral projections 25–60 × 4–8 μm, cylindrical, narrowly clavate, sometimes irregular, thin-walled, smooth. Pileocystidia absent. Stipitipellis a thin cutis of parallel cylindrical hyphae of 2.5–8 μm, with hyaline to pale brown content. Caulocystidia 20–40(–55) × 4–6 μm, cylindrical, clavate, sometimes irregular. Hairs of the stipe surface 58–105 μm long, 10–43 μm wide at the base, composed of parallel cylindrical hyphae of 2–6(–9) μm wide, hyaline, thin- walled. Clamp connections present in all tissues.

Habit, habitat and distribution:—solitary, gregarious to cespitose on the ground in coniferous forest dominated by Larix principis-rupprechtii, Shanxi province, China.

Additional specimens examined:— CHINA. Shanxi province, Wutai county, Wutaishan Mountains, 38°57’9’’N, 111°30’7’’E, 1990 m elev., 23 July 2019, on the ground in coniferous forest dominated by Larix principis-rupprechtii, H. Liu (BJTC FM508!). ibid. Wutai county, Wutaishan Mountains, 38°47’47’’N, 113°48’0’’E, 2060 m elev., 25 July 2019, on the ground in coniferous forest dominated by Larix principis-rupprechtii, H. Liu (BJTC FM583!). ibid. Hebei province, Laiyuan county, Baishishan Mountains, 21 August 2019, G.J. Li and Y.B. Guo (HBAU15111!).