Rhodocybe griseonigrella (Vila, Contu, F. Caball. & Ribes) Vizzini, Vila, Picillo & Contu, 2016

Vizzini, Alfredo, Picillo, Bernardo, Ercole, Enrico, Vila, Jordi & Contu, Marco, 2016, Rhodocybe formosa (Agaricales, Entolomataceae): new collections, molecular data and synonymy, and Rhodocybe griseonigrella comb. nov., Phytotaxa 255 (1), pp. 34-46 : 40-41

Rhodocybe griseonigrella (Vila, Contu, F. Caball. & Ribes) Vizzini, Vila, Picillo & Contu , comb. nov.

MycoBank MB 816077

Basionym: Clitopilus griseonigrellus Vila, Contu, F. Caball. & Ribes, Boll. Assoc. Micol. Ecol. Romana 25 (77–78): 4 (2009). Description based on Vila et al. (2009, in Spanish).

Pileus up to 25 mm broad, at first convex to plano-convex, sometimes with a small central umbo, then flattened, umbilicate only in very old specimens; surface mat, not hygrophanous, felty-tomentose, in young specimens covered by a white to light grey pruina overall (which gradually disappears during development) on a grey to brown-grey background, darkening to blackish when old or bruised; margin not striate, incurved when young, then straight, slightly crenulate and exceeding the lamellae, irregular or lobed in old specimens. Lamellae adnate to subdecurrent, not crowded, somewhat arcuate, thick, rarely forked or interveined, at first dark grey, then pale grey or cream-grey, with faint pinkish hues; lamellulae scarce to abundant, l = 1‒5, depending on the degree of development of the basidiome; edge concolorous, entire or somewhat irregular. Stipe central to clearly eccentric, cylindrical, straight or curved, up to 50 × 3 mm, solid; surface mat, felty-tomentose, covered by a white to light grey pruina on a dark grey to brown backround (as occurs in the pileus); base with white rhizomorphs. Context thin, scarce, grey to grey-brown, darkening to blackish when bruised or old; smell indistinct, fungoid; taste faintly bitter, somewhat mealy.

Spores 5.7‒8 × 4.5‒5.9 μm, on average 6.6 × 5.3 μm, Q = 1.1‒1.5, broadly ellipsoid to subglobose, hyaline, thin-walled, in side and face view strongly nodulose-verrucose, gibbous, angular in polar view, hilar appendix evident, walls inamyloid, non-dextrinoid. Basidia 4‒spored, rarely 2‒spored, 26.7‒32 × 8‒10.7 μm, clavate, without basal clamp. Pseudocystidia very numerous, 29.3‒58.7 × 2.1‒9.1 μm, lageniform to fusiform, sometimes sinuose or mucronate at apex, non-septate, filled with refringent granular pigments (in KOH) strongly dextrinoid (in Melzer’s reagent). Hymenophoral trama consisting of cylindrical hyphae with refringent granular contents yellow in KOH and strongly dextrinoid in Melzer’s reagent. Pileipellis made up of cylindrical, sometimes winding hyphae, 2.4‒6.4 μm wide; pigment epiparietal, abundant, dark brown to grey, strongly incrusting the elements of the suprapellis, less evident or absent in the subpellis. Clamp-connections absent.

Holotype: SPAIN, Catalonia, near La Nau, Serra de Marina, Santa Maria de Martorelles (Barcelona), on a slope, under Quercus ilex L., Q. humilis Mill. , Pinus pinea L., Erica sp. and Cistus sp. , on acidic soil (weathered granite), 320 m a.s.l., 04 December 2008, F. Caballero, LIP JVG 1081204 (LIP!).