Growing terrestrial among grass and fallen leaves under Salix and in pastures and grasslands. Autumn. So far, only found in Norway. Rare or overlooked.

Pileus 7-30 mm across, conical to convex, flattening with age, and +/- recurved margin, mostly with a prominent umbo, pruinose, glabrescent, sulcate, translucent-striate, hygrophanous, black to brownish black to dark sepia brown, or fairly dark grey with a darker, greyish brown to almost black centre, the margin paler to whitish, drying towards grey. Odour nitrous or rancid, but sometimes weak and fugacious. Taste strongly nitrous or rancid. Lamellae (17-)22-30 reaching the stipe, ascending, narrowly adnate, with or without a short decurrent tooth, somewhat rugulose and dorsally intervenose with age, grey to dark grey, the edge convex, paler, grey to whitish. Stipe 30-50 x 1-3(-5) mm, fragile, straight to somewhat curved, equal or somewhat broadened below, terete, hollow, with age often somewhat flattened and occasionally somewhat fissured lengthwise, glabrous (at least in older specimens), becoming shiny, pale grey at the apex, darker greyish or pale brown or grey-brown downwards, paler than the pileus, the base densely covered with long, coarse, flexuous, whitish fibrils.

Basidia (21-)24-35(-39) x (7-)8-9(-12) µm, clavate, 4-spored, with plump sterigmata 2-5(-12) µm long. Spores (7.5-)9-11(-12.5) x 4.3-6.5 µm, Q 1.4-2.3, Qav 1.8-1.9 (n=170), pip-shaped, smooth, amyloid. Cheilocystidia 24-86(-103) x 6-24(-30) x 3.5-6.5 µm, occuring mixed with basidia, but partly forming a sterile band, fusiform to lageniform, neck 10-35 µm long, occasionally with a furcate neck, more rarely clavate or subcylindrical, long- or short-stalked, smooth. Pleurocystidia similar. Lamellar trama dextrinoid, brownish vinescent in Melzer's reagent. Hyphae of the pileipellis 1.2-6.3 µm wide, covered with straight to curved, simple to very much branched excrescences 1-22.5 x 1-3 µm which tend to become covered with gelatinous matter and forming dense masses; 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 1.5-3 µm wide, smooth to sparsely covered with simple, cylindrical excrescences 1-6 x 1.8-2.5 µm; terminal cells (caulocystidia) 2.5-10 µm wide, smooth or with few to fairly numerous, coarse excrescences. Clamps either present or absent.

Spores up to 14 µm long have been observed, probbly coming from a few 2-spored basidia that were seen in one collection together with the 4-spored basidia. In one collection there were numerous cystidia-like, smooth terminal cells of the hyphae of the pileipellis near the pileus margin, in addition to the large diverticulate terminal cells.

Microphotos of the hyphae of the pileipellis

Microphotos of pileipellis and cheilocystidia

More microphotos

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 terminal cells of the pileipellis, and the differently shaped caulocystidia.

The holotype was devoid of clamps, but recent collections confirmed by ITS sequences have proved that this species also can possess clamp connections. This phenomenon is not unknown in sect. Fragilipedes, see for instance M. leptocephala and M. niveipes.

Aronsen & Læssøe (2016) confused clamped collections of M. austera with M. parca. In fact, their photo of M. parca represents M. austera.

Mycena austera is probably a rare species in Norway, but it may have been confused with other nitrous-smelling species of the section. I have seen 14 collections from five different localities.

Additional images