Cyanosporussubungulatus is characterised by shell-shaped pileus with a pale mouse-grey to ash-grey pileal surface when fresh, dark-grey to mouse-grey when dry, allantoid to cylindrical and slightly curved basidiospores (4.5–5.2 × 1.1–1.4 μm).

China. Yunnan Province, Yangbi County, Shimenguan Nature Reserve, on fallen trunk of Pinus sp., 6.IX.2019, Cui 18046 (BJFC 034905).

Subungulatus (Lat.): referring to the species resembling Cyanosporusungulatus in morphology.

Basidiomata annual, pileate, soft corky, without odour or taste when fresh, becoming corky to fragile and light in weight upon drying. Pileus shell-shaped, projecting up to 1.7 cm, 2.8 cm wide and 1.2 cm thick at base. Pileal surface velutinate, pale mouse-grey to ash-grey when fresh, becoming smooth, rugose, dark-grey to mouse-grey when dry; margin obtuse. Pore surface white to cream when fresh, becoming cream to pinkish buff when dry; sterile margin narrow to almost lacking; pores round, 4–6 per mm; dissepiments thin, entire to lacerate. Context white to cream, soft corky, up to 5 mm thick. Tubes pale mouse-grey to ash-grey, fragile, up to 6 mm long.

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

Generative hyphae hyaline, slightly thick-walled with a wide lumen, rarely branched, loosely interwoven, 2.5–6.4 μm in diam.

Generative hyphae hyaline, slightly thick-walled with a wide lumen, occasionally branched, interwoven, 2–4.2 μm in diam. Cystidia and cystidioles absent. Basidia clavate, bearing four sterigmata and a basal clamp connection, 13.6–17.8 × 3–5.5 μm; basidioles dominant, in shape similar to basidia, but smaller, 12.8–17.2 × 2.4–5.2 μm.

Basidiospores allantoid to cylindrical, slightly curved, hyaline, thin- to slightly thick-walled, smooth, IKI–, CB–, (4.3–)4.5–5.2 × 1.1–1.4 μm, L = 4.73 μm, W = 1.22 μm, Q = 3.48–3.66 (n = 60/2).

Brown rot.

China, Yunnan Province, Xichou County, Xiaoqiaogou Nature Reserve, on fallen angiosperm trunk, 14.I.2019, Zhao 10833 (SWFC 010833).