Entoloma chalybeum (Fr. : Fr.) Noordel. [as‘chalybaeum’]
Index Fungorum number: 528909
Pileus 10—35 mm broad, at first hemisphaerical then expanding to conico-convex, with a slightly depressed centre, with involute then deflexed margin, not hygrophanous, at first entirely velutinose to thinly squamulose, becoming radially fibrillose and almost glabrescent towards margin with age, translucently striate with age, dark blue (19E5—6) to blackish blue (19F5—6) in centre, discolouring with age to brownish grey (5C2) with bluish centre and squamules. Lamellae moderately distant, emarginate-adnate or almost free in old basidiomata, at first bluish then beige-pink with a grayish tint, with entire concolorous edge. Stipe 20—50 _ 1.5—2 mm, cylindrical or slightly broadened towards the base, fistulose, deep blue (19E7—8) in the upper part, paler towards the base, becoming bluish grey with age, smooth, glabrous, polished, with a pruinose apex and white tomentose base. Context concolorous with the surface, paler in the inner part. Odour and taste indistinct. Spores 9.2—11.1 _ 6.1—7.3 μm, Q = 1.4—1.7, heterodiametrical with 6—7 angles in side view. Basidia 26.1—33.9 _ 8.5—11.1 μm, 2—4-spored, clavate, clampless. Lamellae edge sterile. Cheilocystidia clavate to broadly clavate, vesiculose or sphaeropedinculate, often septate, with terminal cells 22.1—44.0 _ 6.5—16.7 μm, colourless. Pileipellis a plagiotrichoderm with transition to a trichoderm in centre, made up of cylindrical hyphae with inflated terminal elements, 8—16 μm wide, without clamp connections. Pigment blue, intracellular. Oleiferous hyphae and brilliant granules absent.
Distribution: Europe (typus); Russian Far East (as Rhodophyllus lazulinus (Fr.) Quél.) (Vassiljeva, 1973); Vietnam.
Collection examined: Vietnam, Lam Dong Prov., Lac Duong Dist., Bidoup-Nui Ba National Park, Giang Ly Ranger Station, 12°11´08´´ N, 108°40´49´´ E, 1450 m alt., on rotten wood in evergreen mixed forest, 3 July 2010, leg. E. Popov, LE 262951.
Notes: Entoloma chalybaeum is recognized by its blue gills with a sterile, non-serrate edge. It has a wide distribution and is rather common in European grasslands, but may occur also in forests. Thus, finding this species in the forest in a montane region in Vietnam was not surprising. However, growth on rotten wood is unusual. Our specimen also differs slightly from European collections by the shape of cheilocystidia. For this reason, comparing of these collections on molecular level could be relevant.