Gregarious among needles under Juniperus communis or on open lawns. Autumn. M. parca has been found at three localities in the South East of Norway. Robich (2003: 277-280) reported it from Italy. Recently it has also been recorded from Denmark. See records in The Norwegian Mycological Database.

Pileus 7-30 mm across, conical, parabolical, convex to plane, often with recurved margin with age, usually with a prominent, obtuse umbo, sulcate, translucent-striate, hygrophanous, at first pruinose, glabrescent, brownish black to dark brownish grey with a blackish centre, fading to grey, margin grey to whitish. Odour indistinctive, raphanoid or experienced as nitrous. Taste strong, nitrous or somewhat rancid. Lamellae 17-26 reaching the stipe, ascending, narrowly adnate, with or without a short tooth, somewhat rugulose and dorsally intervenose with age, grey to dark grey with pallid to white edge. Stipe up to 60 x 3 mm, straight to somewhat curved, terete, with age sometimes flattened, and occasionally somewhat fissured lengthwise, hollow, equal or somewhat broadened below, fragile, glabrous, becoming shiny, apically pale grey, brown to grey-brown below, becoming entirely grey, the base covered with long, coarse, flexuous, whitish fibrils.

Basidia c. 27 x 7 µm, clavate, 4-spored, clamped, with sterigmata c. 7 µm long. Spores 7-9 x 4.5-6 µm, Q 1.3-1.7, Qav ~ 1.6, pip-shaped, smooth, amyloid. Cheilocystidia 38-68(-80) x 0-16 x 2.5-5 µm, forming a sterile band, lageniform, smooth. Pleurocystidia similar, not numerous. Lamellar trama dextrinoid, brownish vinescent in Melzer's reagent. Hyphae of the pileipellis 2.7-4.5 µm wide, not very densely covered with cylindrical, curved to flexuous excrescences 4.5-18 x 1.8-2.2 µm. Hyphae of the cortical layer of the stipe 1.6-3.5 µm wide, smooth, terminal cells scarce, 45-65 x 5.5-7 µm, clavate. Clamp connections present at all tissues (but clamps sometimes hard to detect).

Microphotos of cheilocystidia

Microphotos of hyphae of the pileipellis

Mycena parca is a member of the large and complex section Fragilipedes (Fr.) Quél. It is closely related to the widely distributed species Mycena leptocephala (Pers.: Fr.) Gillet, from which it can be distinguished only by a close microscopic examination. The type is described as a non-smelling, grey species. That was probably influenced by dry weather. Later records have shown that it is a much darker species, more or less with a nitrous odour. It can normally be separated from M. leptocephala by the stipe, which is conspicuously glabrous. The large, lageniform cheilocystidia should also be a good character.