Pleurotus tuber-regium

Pilei 2.5–19 cm wide, deeply infundibuliform, brownish fuliginous and minutely scurfy squamulose, then pale and minutely, but interruptedly white from the centre outwards, not scaly; margin incurved on maturing, strongly on drying, with small floccose fragments of the veil. Stipe 30–90 x 4–19 mm, central, subcylindric, concolorous and minutely scurfy squamulose as the pileus. Veil minute, attaching to the apex of the stem, to the very young pileus greyish subfloccose, soon rupturing and disappearing. Lamellae deeply decurrent, very crowded, thin, narrow, 0.3–0.8 mm wide, mostly dichotomous, cream-white to subochraceous, with entire fuscous-grey edge, very sinuous on drying; no hyphal pegs. Context 2–4 mm thick in the centre of the pileus, at first cheesy and hard, then coriaceous, white. Smell mushroomy.

Basidiospores 7–10 × 3–4.5 μm, white, smooth, subcylindric, inamyloid and thin walled. Basidia 22–37 × 5–7 μm; 4 sterigmata. Cheilocystidia 22–48 × 4.5–7.5 μm, subcylindric, subclavate, subventricose, projecting, thin-walled, smooth, as a sterile edge. Pleurocystidia and hyphal pegs absent. Hyphae dimitic with skeletal and generative hyphae. Generative hyphae 2–8 μm, not inflating, with a slightly thickened wall, frequently branching with prominent clamp connections. Skeletal hyphae 2–7 μm, hyaline or pale stamineous, with a thickened wall, rarely branched, and a narrow but distinct lumen. Gill-trama with radiate construction. Fruiting bodies are formed from tuber-like, uneven, oblong, dark brown with white context, 12–15 cm diameter sclerotia within rotten wood. (Fig. 1)

Specimen examined: CHINA, Jiangxi Province, Fuzhou City, 6 February 2015; from JingShan mushroom growing company; Jinshan Fang (ZRL-2015304, HMAS: 253940); CHINA, Yunnan Province, Xishuangbanna, Mengsong Village; UTM-N2379744.485281, UTM-E653217.753714; alt. 1600m; 8 July 2013; on rotting wood; Samantha C. Karunarathna (MFLU 14-0743).

Habitat and distribution: on buried rotten wood in rain forest, solitary. Widely distributed in Australia, Chad Republic, China, Ghana, India, Ivory Coast, Kenya, Liberia, Madagascar, Malaysia, Middle Congo, Nigeria, Papua New Guinea, Samoa, Sierra Leone, Solomon Islands, Sri Lanka, Tanzania, Thailand, Uganda, Zaire Republic, Zambia, Zanzibar, and Zimbabwe.