Xylodon asiaticus X.C. Zhang & C.L. Zhao, sp. nov. Figs. 3, 4

MycoBank no.: MB 850228

Etymology: — asiaticus (Lat.): referring to the provenance (Asian) of the type specimen.

Diagnosis: — It differs from other Xylodon species by its buff to orchraceous and hynoid hymenial surface, a monomitic hyphal system with clamped generative hyphae and ellipsoid to subcylindrical basidiospores measuring (3.7)4–5.2(–6) × (2.5–)2.8–3.5(–4) µm.

Holotype: — CHINA. Yunnan Province, Dali, Nanjian County, Lingbaoshan National Forest Park, 24°46′58′′N, 100°30′46′′E, elev. 2523 m, on fallen angiosperm branch, 10 January 2019, leg. C.L. Zhao, CLZhao 10368 (SWFC!), GenBank No. (ITS OM959479; nLSU OM967417).

Basidiomata: — Annual, resupinate, adnate, coriaceous, very hard to separate from substrate, without odor or taste when fresh, up to 15 cm long, 2 cm wide, less than 1 mm thick. Hymenial surface hydnoid, aculei 4–6 per mm, up to 0.5 mm long, buff when fresh, turning to buff to ochraceous upon drying. Sterile margin distinct, slightly buff, up to 1 mm wide.

Hyphal structure: — Hyphal system monomitic, generative hyphae with clamp connections, colorless, thin-walled, branched, interwoven, 2–3.5 μm in diameter; IKI–, CB–, tissues unchanged in KOH.

Hymenium: — Cystidia and cystidioles absent. Basidia barrelled to subcylindrical, with 4 sterigmata and a basal clamp connection, 11.5–20 × 4–5 µm; basidioles dominant, similar to basidia in shape, but slightly smaller.

Basidiospores: — Ellipsoid to subcylindrical, colorless, smooth, thin-walled, with 1–2 oil drops, IKI–, CB–, (3.7)4–5.2(–6) × (2.5–)2.8–3.5(–4) µm, L = 4.72 μm, W = 2.97 µm, Q = 1.59–1.91 (n = 120/4).

Type of rot: — White rot.

Additional specimens examined: — CHINA. Yunnan Province, Yuxi, Xinping County, Mopanshan National Forestry Park, 23°55′48′′N, 101°59′22′′E, elev. 2150 m, on the trunk of Quercus semecarpifolia, 19 August 2017, leg. C.L. Zhao, CLZhao 2282 (SWFC!), GenBank No. (ITS OM959481; nLSU OM967416); Dali, Nanjian County, Lingbaoshan National Forest Park, 24°46′58′′N, 100°30′46′′E, elev. 2522 m, on fallen angiosperm branch, 10 January 2019, leg. C.L. Zhao, CLZhao 10430 (SWFC!), GenBank No. (ITS OM959480; nLSU OM967418); Wenshan, Xichou County, Pingzhai Forestry Farm, 23°26′27′′N, 104°40′48′′E, elev. 1500 m, on fallen angiosperm branch, 18 January 2019, leg. C.L. Zhao, CLZhao 11531 (SWFC!), GenBank No. (ITS OM959471).

Notes:— Morphologically, Xylodon asiaticus resembles X. asper (Fr.) Hjortstam & Ryvarden. (2009: 34), X. australis (Berk.) Hjortstam & Ryvarden. (2007: 98) and X. tenuicystidius (Hjortstam & Ryvarden) Hjortstam & Ryvarden. (2009: 41) in having ellipsoid or cylindrical basidiospores. However, X. asper can be delimited from X. asiaticus by its odontioid hymenial surface and longer basidia (20–25 × 4–5 µm, Hjortstam & Ryvarden 2009); X. australis is distinguished from X. asiaticus by its grandinoid hymenial surface and larger basidiospores (6–7.5 × 4–4.5 µm, Hjortstam & Ryvarden 2007); X. tenuicystidius differs from X. asiaticus by its tuberculate hymenial surface and longer basidia (20–25 × 3–4 µm, Hjortstam & Ryvarden 2009).