Mycena obtecta Maas Geest.

Proc. K. Ned. Akad. Wet. 96(3): 343 (1993)

Basidiomata cespitose on a stump of a deciduous tree. Only recorded fromt the type locality.

Pileus 15 - 28 mm across, conical to campnulate, umbonate, finally convex, translucent-striate, subtomentose, matted when dried, pale greyish brown, darker at the centre, becoming spotted with vinaceous brown stains. Flesh c. 1 mm broad, pallid. Odour absent. Lamellae c. 22 reaching the stipe, tender, ascending, up to 2 mm broad, ventricose, adnate to somewhat sinuate, whitish with some pinkish tint, becoming spotted with vinaceous stains, the edge convex, concolorous. Stipe 50 - 80 x 1 - 2 mm, hollow, not fragile, equal, terete, straight to somewhat curved, apically minutely puberulous, glabrescent farther below, finely innate-striate, at first watery whitish, then turning pale greyish brown from base upwards, becoming spotted with vinaceous red stains, the base covered with long, coarse, whitish fibrils.

Basidia 27-36 x 7-9 µm, clavate, 4-spored, clamped, with sterigmata 6.5-7 µm long. Spores 8.8-9.4 x 5.8-6.7 µm, pip-shaped, smooth, weakly amyloid. Cheilocystidia 30-70 x 5.5-9 x 2-5 µm, fusiform, sublageniform, subcylindrical, clamped, apically either narrowed into a slender and frequently torulose neck and moreover smooth towards the middle of the lamella, or variously and more or less strongly branched near the margin of the pileus, with the excrescences 6.5-16 x 1.8-2.5 µm. Pleurocystidia absent. Lamellar trama brownish vinescent in Melzer's reagent. Hyphae of the pileipellis 2-4.5 µm wide, clamped, thickly covered with much branched excrescences 2-45 x 1.3-2 µm which form intricately entwined, dense masses. Hyphae of the cortical layer of the stipe 0.9-2.7 µm wide, clamped, smooth for the greater part but towards the apex of the stipe sparsely covered with scattered, detersile, cylindrical excrescences 4.5-13.5 x 0.9-1.5 µm.

The description is adopted entirely from Maas Geesteranus (1993: 343-345), who claimed that the present species possesses a combination of characters that is unique in sect. Fragilipedes: vinaceous spots, cheilocystidia with a torulose neck, and hyphae of the pileipellis whose excrescences form an uncommonly thick layer. In my opinion, it could represent a deviating form of M. polygramma, which was confirmed by a recent ITS-sequence of the holotype obtained in the Norwegian Barcode Project (NorBOL) from material kindly put to our disposal from the herbarium in Leiden (L).

TELEMARK: BAMBLE, Gjømle 23 Sept. 1982, Ø. Weholt M51/82 (No. 982.329-934; L) (holotype).

Reference: Maas Geesteranus (1993: 343- 345).


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