Cyanosporustenuicontextus is characterised by flabelliform pileus with a velutinate, cream to pinkish buff with a little blue tint pileal surface when fresh, becoming glabrous, light vinaceous grey to pale mouse-grey when dry, small and round pores (6–8 per mm), thin context (up to 0.8 mm) and allantoid basidiospores (3.8–4.3 × 0.8–1.2 μm).

China. Yunnan Province, Lanping County, Tongdian Town, Luoguqing, on fallen trunk of Pinus sp., 19.IX.2017, Cui 16280 (BJFC 029579).

Tenuicontextus (Lat.): referring to the species having thin context.

Basidiomata annual, pileate, soft corky, without odour or taste when fresh, becoming corky to fragile and light in weight upon drying. Pileus flabelliform, projecting up to 1.3 cm, 3.2 cm wide and 0.5 cm thick at base. Pileal surface velutinate, cream to pinkish buff with a little blue tint when fresh, becoming glabrous, light vinaceous grey to pale mouse-grey when dry; margin acute. Pore surface white to cream when fresh, becoming pinkish buff to buff when dry; sterile margin narrow to almost lacking; pores round, 6–8 per mm; dissepiments thin, entire to lacerate. Context cream to buff, soft corky, up to 0.8 mm thick. Tubes pale mouse-grey to buff, fragile, up to 4.3 mm long.

Hyphal system monomitic; generative hyphae with clamp connections, IKI–, CB–; hyphae unchanged in KOH.

Generative hyphae hyaline, thin- to slightly thick-walled with a wide lumen, occasionally branched, loosely interwoven, 2.3–5.5 μm in diam.

Generative hyphae hyaline, thin- to slightly thick-walled with a wide lumen, occasionally branched, interwoven, 2–4 μm in diam. Cystidia absent; cystidioles present, fusoid, thin-walled, 9.5–14.6 × 2.8–3.4 μm. Basidia clavate, bearing four sterigmata and a basal clamp connection, 11.7–16.8 × 3.4–4.3 μm; basidioles dominant, in shape similar to basidia, but smaller, 10.6–14.7 × 2.9–3.6 μm.

Basidiospores allantoid, slightly curved, hyaline, thin- to slightly thick-walled, smooth, IKI–, CB–, (3.7–)3.8–4.3 × 0.8–1.2 μm, L = 3.97 μm, W = 1.02 μm, Q = 3.78–4.26 (n = 60/2).

Brown rot.

China. Yunnan Province, Yuxi, Xinping County, Mopanshan National Forest Park, on angiosperm stump, 16.I.2017, Zhao 813 (SWFC 000813).