Entoloma griseorhodopolium Montanez, Noordeloos & Guzmán-Dávalos, 2016

Montañez, Diego, Noordeloos, Machiel E., Rodríguez, Olivia, Vargas, Ofelia & Guzmán-Dávalos, Laura, 2016, Notes on the genus Entoloma (Basidiomycota, Agaricales) in two volcanic areas of Jalisco, Mexico, Phytotaxa 277 (3), pp. 211-236 : 215-216

2. Entoloma griseorhodopolium Montanez, Noordeloos & Guzmán-Dávalos , sp. nov., FIGURE 2 .

Mycobank No. 817353

Etymology:—griseus = grey, referring to the grey pileus of this species, which otherwise is similar to E. rhodopolium .

Diagnosis:—Pileus up to 70 mm diam. and stipe up to 70 × 8 mm; pileus hygrophanous, dark greyish brown or dark grey; stipe whitish, some with brownish or greyish fibrils at the apex; odour imperceptible to farinaceous. Pileipellis an ixocutis, hyphae with yellowish brown both plasmatic and vacuolar pigment.

Description:— Pileus 13–70 mm broad, convex-campanulate, convex, plano-convex to plane, some umbonate or subumbonate, hygrophanous, dull or translucent-striate at the margin, glabrous to slightly fibrillose, smooth, dark greyish brown to dark grey. Lamellae adnate to emarginate, some with decurrent tooth, subdistant, ventricose, whitish then pink, edge entire, crenate, or eroded, concolourous. Stipe 19–70 × 2–8 mm, central, cylindrical, equal or broadening towards the base, fibrillose, occasionally with pruinose apex, longitudinally striate, whitish, some with pale brown, grey, or whitish fibrils at the apex. Context fleshy, white to whitish. Odour none to farinaceous. Taste farinaceous.

Basidiospores 7.2–10.4 × 6.4–8.8 μm, Lm = 8.8, Wm = 7.6, Q = 1.0–1.3, isodiametrical to subisodiametrical, rarely heterodiametrical, 5–7 angled, colourless. Basidia 26–48 × 8–13 μm, 4-spored, clavate to cylindro-clavate, colourless, clamped. Pleurocystidia absent. Cheilocystidia absent. Pileipellis an ixocutis, terminal elements 24–28 × 8–12 μm, clavate to cylindro-clavate and difficult to distinguish, without a differentiated subpellis, with scarce to abundant yellowish brown plasmatic and vacuolar pigment. Caulocystidia 18–65 × 5–12 μm, cylindro-clavate to slightly lageniform, colourless or yellowish, scarce to abundant at the stipe apex, sometimes absent. Clamp-connections present, abundant on the hymenophoral trama.

Habit and habitat:—Solitary or gregarious, on soil, in Pinus - Quercus forest and cloud forest.

Material studied:— MEXICO. Jalisco, Municipality of Tequila, volcán de Tequila, 14 October 1990, L. Guzmán-Dávalos 5239 (Holotype, IBUG!). Municipality of Zapotlán el Grande, slopes of Nevado de Colima, El Floripondio, 10 August 1991, O. Vargas 528 (IBUG!).

Comments:—Both collections are characterized by a grey to greyish brown pileus and white, pale brown, or pale grey stipe, and fit well in Entoloma subgen. Rhodopolia sect. Rhodopolia , also on account of the microscopic characters. In many ways, our collections are similar to E. griseum Peck (1904) and are in agreement with the type studies by Noordeloos (2008) and Kokkonen (2015). Largent (1994) did not record it. A modern description of Peck species can be found on the Internet ( Kuo 2014). Interestingly, Kuo states that clamp-connections are absent, which is in contradiction with the type studies. Entoloma rhodopolium differs by the paler pileus that is translucent-striate at margin up to half the radius, and E. nigrobrunneum Hesler (1967) is much darker and has a well-differentiated subpellis ( Noordeloos 1988). None of the species described in Noordeloos (2004) match our material. Considering the rather confusing situation in the Rhodopolia (see also Kokkonen 2015), it seems best to describe the Mexican specimens as a new species.

Figures

FIGURE 2. Entoloma griseorhodopolium. a. Basidiospores. b. Basidia. c. Pileipellis. d. Caulocystidia. All 1000×, except basidiospores 3000×. Drawings by Diego Montañez and Machiel Noordeloos.