Adustochaete albomarginata J. H Dong & C. L. Zhao 2024, sp. nov.

Adustochaete albomarginata J. H Dong & C. L. Zhao sp. nov. Figs 4, 5, 6 Diagnosis. Differs from other Adustochaete species by its soft membranaceous basidiomata with cream to buff, smooth, cracked hymenial surface, a monomitic hyphal system with clamped generative hyphae and subcylindrical to allantoid basidiospores measuring 12–17.5 × 6.5–9 µm. Holotype. China • Yunnan Province, Dali, Weishan County, Leqiu Town, Zhongyao Village, 25 ° 01 ′ N, 100 ° 19 ′ E, altitude 1910 m, on the fallen branch of angiosperm, leg. C. L. Zhao, 19 July 2022, CLZhao 22774 (SWFC). Etymology. albomarginata (Latin or Greek origin): referring to the white margin of the basidiomata. Basidiomata. Annual, resupinate, closely adnate, soft membranaceous, very hard to separate from substrate, without odour or taste when fresh, becoming coriaceous upon drying, up to 5 cm long, 1.5 cm wide, 50–100 µm thick. Hymenial surface smooth, white to cream when fresh, turning to cream to buff upon drying, cracked. Sterile margin white, thinning out, up to 0.5 mm wide. Hyphal system. Monomitic, generative hyphae with clamp connections, colourless, thin-walled, unbranched, interwoven, 2.5–3.5 µm in diameter; IKI –, CB –, tissues unchanged in KOH. Hymenium. Cystidia numerous, thin-walled, subclavate to fusiform with an acute or obtuse apex, occasionally sinuous in the basal, 23.5–48.5 × 10–13.5 µm, with a clamp connection at base; cystidioles absent. Hyphidia arising from generative hyphae, nodulose, branched, colourless, thin-walled, 2.5–5 µm in diameter. Basidia ellipsoid to ovoid, longitudinally septate, two to four-celled, 17–24.5 × 11–16.5 µm; basidioles dominant, similar to basidia in shape, but slightly smaller. Basidiospores. Subcylindrical to allantoid, slightly curved, colourless, smooth, thin-walled, with 1–2 oil drops, IKI –, CB –, (11.5 –) 12–17.5 (– 18) × 6.5–9 (– 9.5) µm, L = 14.66 µm, W = 7.80 µm, Q = 1.72–1.99, Q m = 1.88 ± 0.08 (n = 30 / 1).