Psathyrella bifrons (Berk.) A.H. Sm

Diagnosis fuente:  PERSOONIA - Suplement - Vol. 2 - THE DUTCH, FRENCH AND BRITISH SPECIES OF PSATHYRELLA - 1985 E. KITS VAN WAVEREN - Rijksherbarium, Leiden, The Nederlands
Cap at first (primordia: cap 3-5 mm) ellipsoid, dark reddish brown (Mu. 5 YR 3/4—4/4) or dark yellowish brown (Mu. 5 YR 4/6), not striate, later (cap 8-10 mm) hemispherical-paraboloid, reddish (Mu. 5 YR 4/4, 4/6) only at centre, for the rest dark brown (Mu. 7.5 YR4/4), paler towards margin, at margin ochraceous. Mature caps 15—45(—50) mm, 11-30 mm high, broadly obtuse, paraboloid, sometimes subhemispherical, in final stages sometimes vaguely lobed, sometimes with grooved surface, very thin slightly revolute extreme margin, dark ochre brown with a faint reddish hue (Mu. 5 YR 5/6, 5/8, 6/6), paler towards margin (Mu. 7.5 YR 7/6, 8/6); finally pale sordid ochre-brown (Mu. 10 YR 5/4, 6/4),sometimes in some areas with a trace of grey or purplish, striate almost up to centre, hygrophanous, drying out to pale alutaceous, very pale yellowish brown or sordid white (Mu. 10 YR 8/4, 8/3), slightly darker at centre, sometimes slightly micaceous, rugulose, without pink. Veil rather strongly developed, in young stages forming white fibrils and bundles of fibrils or even flocci arranged at random on cap, reaching up to 1/2—2/3 from margin and increasing in number towards margin, sometimes appendiculate flocci and denticles, easily detersile, in mature specimens usually absent. Gills 46 mm broad, slightly ventricose near margin of cap, thenstraight and ascending, broadly adnate with tooth, in very young specimens pale brown (Mu. 10 YR 7/2, 7/3) at base, whitish towards and white near edge, at maturity according to Kihner & Romagnesi tobacco brown (see observations); edge white. Stem 70-180 x 2-4 mm, straight, rather firm, cylindrical or slightly thickening towards base, whitish in upper part, isabelline to pale brown in lower 2/3, sordid brown at base, hollow, rooting (pseudorrhiza short, 4-10 mm, easily overlooked); base strongly strigose with white and often long hairs; apex pruinose. Flesh of cap 1.5 mm thick in centre, sordid ochre brown, of stem pale brown, darker at base, white in upper part. Trama of ‘washed’ gill distinctly brown (Mu. 10 YR 6/3, 6/4, 5/6) in a fairly narrow zone along base, for the rest pale brown (Mu. 10 YR 7/3, 7/4) up to edge. Spore print purplish black. Spores 11.5—14.5 x 6.5—7.5 pm (mean values 12.5—12.9 x 6.5—6.8 pm: 5 collections) excluding spores 14.9 ym or longer (37 spores out of a total of 250 spores measured, probably coming from 2- or 1-spored basidia), ellipsoid but adaxially flattened, in water red (Mu. 2.5 YR 3/6), in NHs,OH 10% and KOH 5% dark brown (Mu. 5 YR 4/3, 3/3), opaque; germ pore very distinct, + 2 um; hilar appendix distinct. Basidia 17.5—33.5 x (10.5—)11—12 pm, 4-spored (some 2-spored, very few 1-spored). Pleurocystidia 45-70 x 10—15(—17.5) pm, fairly numerous, lageniform with apex sometimes slightly swollen, thin-walled, colourless. Marginal cells: pleurocystidioid cheilocystidia 20-45(—50) x (S—)7.5-12.5 um, abundant, densely packed, intermixed with a small number of hardly noticeable spheropedunculate and clavate cells, 10-20 x 2.5—7.5 pm, thin-walled, colourless. Hymenophoral trama in NH,OH 10% sub micr. distinctly brownish from base to edge from membranal pigment, strongest in basal half, yellow hyphal septa and some encrustations. Pileipellis a2-4 cells deep layer of subglobose colourless cells, 32-48 ym diam..
HABITAT & DISTRIBUTION. — Gregarious, terrestrial in clayey soil against small pieces of wood, Oct.-Nov. Very rare in the Netherlands. Reported from France and by Berkeley and other early British authors from the British Isles, but not known by present-day British mycologists.