Entoloma nubilum Manim., Leelav. et Noordel.
Index Fungorum number: IF 374822
Basiomata pleurotoid. Pileus 3–7 mm broad, cupulate then reniform with incurved then lobate margin, not hygrophanous, slightly translucently striate, tomentose to finely squamulose, deep blue to dark blue (20D8, 20E7–8). Lamellae moderately distant intermixed with lamellulae, adnate or slightly emarginate, whitish
to bluish near the cup margin then pinkish with a concolorous entire edge. Stipe 3–4 × 0.5–1 mm, reduced, eccentrical or lateral, curved, pruinose to tomentose, concolorous with the pileus or slightly paler (20D7), with white arachnoid mycelial strands at the base attached to the substratum. Context thin, bluish, under the surface dark blue. Odour indistinct, taste not reported. Spores 7.9–9.1 × 5.4–6.3 μm, Q = 1.3–1.8, heterodiametrical, with 6–8 angles in side view. Basidia 23.0–30.9 × 9.2–12.0 μm, clavate, clampless. Lamellae edge fertile. Cheilocystidia and pleurocystidia absent. Pileipellis a cutis with transition to a trichoderm. Pigment dark blue, intracellular. Clamp connections, oleiferous hyphae and brilliant granules absent.
Distribution: India (typus); Vietnam.
Collection examined: Vietnam, Dong Nai Prov., Tan Phu Dist., Cat Tien National Park, «Lagerstroemia trail» near the Park’s Headquarters, 11°25´36´´ N, 107°25´35´´ E, 125 m alt., on a fallen log in lowland semi-deciduous tropical forest, 14 June 2010, leg. A. Kovalenko, LE 262915.
Comments: Only three blue pleurotoid Entoloma species have been described to the present day. E. cyanomelaenum (Boedijn) Manim., Leelav. et Noordel. Described from Sumatra and E. cyaneum (Murrill) Hesler [non E. cyaneum (Peck) Sacc.] from Florida possess larger (9–11 × 5.5–6.5 and 8–10 × 6–7 μm correspondingly) spores. The second species is characterized also by the moderately well-developed white stipe. We have identified our collection as E. nubilum on account of the small spores in spite of the lignicolous.