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Mycena austera Aronsen

Persoonia 15 (4): 531 (1994).

Mycena austera

© A. Aronsen 1991 (holotype)


Growing terrestrial among grass and fallen leaves under Salix.

Pileus up to 20 mm across, conical to convex, flattening with age, mostly with a prominent umbo, translucent-striate, sulcate, hygrophanous, fairly dark grey with a darker, greyish brown to almost black centre, the margin paler to whitish. Odour nitrous. Taste not recorded. Lamellae 26-30 reaching the stipe, ascending, narrowly adnate, with or without a short decurrent tooth, somewhat intervenose with age, grey to dark grey, the edge convex, paler. Stipe up to 50 x 3 mm, straight to somewhat curved, terete, hollow, glabrous (at least in older specimens), pale grey at the apex, darker greyish downwards, paler than the pileus, the base densely covered with long, coarse, flexuous, whitish fibrils.

Basidia 29-35 x 8-9 µm, clavate, 4-spored, clampless, with plump sterigmata 9-12 µm long. Spores 9.3-11(-12.5) x 5-6.5 µm, Qav ~ 1.8, pip-shaped, smooth, amyloid. Cheilocystidia 50-103 x 13-24 x 3.5-6.5 µm, clampless, occuring mixed with the basidia, fusiform, smooth. Pleurocystidia numerous, similar. Lamellar trama brownish vinescent in Melzer's reagent. Hyphae of the pileipellis 2.7-6.3 µm wide, clampless, covered with simple to very much branched excrescences 2.5-22.5 x 2 µm which tend to become covered with gelatinous matter; terminal cells 45-70 x 12.5-24 µm, variously shaped, subcylindrical, fusiform, clavate, frequently covered with coarse excrescences 4.5-11 x 2.5 µm. Hyphae of the cortical layer of the stipe 1.8-2.5 µm wide, clampless, smooth to sparsely covered with simple, cylindrical excrescences 1.8-4.5 x 1.8-2.5 µm; terminal cells (caulocystidia) 2.5-10 µm wide, with few to fairly numerous, coarse excrescences.

Mycena austera is a member of sect. Fragilipedes (Fr.) Quél. where it keys out close to the American species M. deceptor Maas Geest. (Maas Geesteranus, 1992). In the latter, however, the pileus is smaller and pale vinaceous brown, dingy brown or greyish brown, 14-22 lamellae are reaching the stipe, the lamellae are whitish, and the odour is indistinctive. In addition the conspicuous, variously shaped terminal cells of the hyphae of the pileipellis in M. austera will separate the two species.

Among the Norwegian species M. austera macroscopically can be mistaken for M. leptocephala (Pers.) Gillet, but it can be told apart from that species on account of the absence of clamp connections, the terminal cells of the pileipellis, and the differently shaped caulocystidia.

It is probably a rare species in Norway, but it may have been confused with other nitrous-smelling species of the section. So far only two collections are known.

Additional images

Collections:

Vestfold, Nøtterøy, Torød, 4 Nov. 1991, A. Aronsen A 16b/91; 5 Nov. 1991, A. Aronsen A 17/91; holotype (O, no. O-F72674), Akershus, Rælingen, Teigen, 13 Oct. 2013, leg. Jørn Langbråten (O)

 

© Arne Aronsen 2002-2016