Psathyrella casca (Fr.) Konrad & Maubl

Diagnosis fuente: PERSOONIA - Suplement - Vol. 2 - THE DUTCH, FRENCH AND BRITISH SPECIES OF PSATHYRELLA - 1985 E. KITS VAN WAVEREN - Rijksherbarium, Leiden, The Nederlands
Cap 20-30 mm, at first paraboloid or hemispherical, then spreading to convex, dark reddish brown (Mu. 5 YR 3/4), rapidly changing into dark warm brown (Mu. 5 YR 4/4), not striate but finely rugulose, hygrophanous, drying out to very pale brown (Mu. 10 YR 7/4) at centre, still paler (Mu. 10 YR 8/3) elsewhere, without pink, not micaceous but regulose in peripheral 2/3. Veil very strongly developed, white, in early stages forming a thick velar pelt of radially arranged fibrils and fascicles of fibrils up to 10 mm from margin, in places also forming a 1 mm broad appendiculate belt along margin, at maturity leaving dense wickerworks of fibrils on marginal zone and on stem many scattered fibrils. Gills 3~5 mm broad, ventricose, broadly adnate, at first very pale brown (Mu. 10 YR 7/3), towards edge paler ventricose, broadly adnate, at first very pale brown (Mu. 10 YR 7/3), towards edge paler (Mu. 10 YR 7/2), at maturity dark sordid brown (Mu. 7.5 YR 3/2, 4/2), with purplish hue, with white fimbriate edge. Stem tall and very hollow (cavity 3—S mm wide, penetrating into flesh of cap), 70-75 x 3-4 (apex) . . . 5—7 (near base), not rooting, firm, snow-white, cream coloured below, in upper half finely longitudinally striate with apex very finely pruinose, in lower half finely fibrillose, at base covered by whitish down. Flesh of cap 1—2 mm thick in lower half finely fibrillose, at base covered by whitish down. Flesh of cap 1—2 mm thick in centre, dark reddish brown (+ Mu. 5 YR 3/2), of stem white, cream alongside cavity. Trama of ‘washed’ gill at base very pale brown (Mu. 10 YR 7/4), paler towards edge. Spore print purplish black. Spores 7-8 x 4.5—5 pm (mean values 7.7 x 4.5 ym: 1 collection), shape variable, most spores in face view ellipsoid, but some ellipsoid-ovoid, in profile usually ellipsoid, adaxially spores in face view ellipsoid, but some ellipsoid-ovoid, in profile usually ellipsoid, adaxially flattened, but some slightly phaseoliform, in water warm brown with reddish hue (Mu. 5 YR4/6), in NH,OH 10% dark brown (Mu. 5 YR 4/4), in KOH 5% dark sordid brown (Mu. 10 YR 4/2), not opaque, with fairly distinct germ pore (+ 1 ym) and small hilar appendix. Basidia 17.5—24 x 8—9.5 um, clavate, 4-spored. Pleurocystidia 35—45(—55) x 10-12 pm, fairly numerous, utriform-pedicellate, thin-walled, colourless. Marginal cells: exclusively rather large spheropedunculate and clavate cells, mostly 15-30 x 9—15 jum but a fair number even 30-40 x 15-17.5(—20) pm; pleurocystidioid cheilocystidia practically absent (see observations); all cells thin-walled and colourless. Hymenophoral trama in NH,OH 10% sub micr. very pale yellowish brown from membranal pigment, without yellow septa or encrustations. Pileipellis a 2—3 cells deep layer of colourless subglobose cells, 25—40 um diam.
HABITAT & DISTRIBUTION. — Terrestrial against piece of wood in clayey soil of deciduous wood. Aug. Very rare in the Netherlands. Reported from France, not from the British Isles.