Generally gregarious on fallen needles of coniferous trees, but occasionally on litter of deciduous trees. Autumn. Widespread but possibly often overlooked. Widely distributed in Southern Norway but not common.

Pileus 5-25 mm across, conical, obtusely conical, campanulate or parabolical, at age sometimes somewhat depressed centrally, pruinose, glabrescent, shallowly sulcate, translucent-striate, hygrophanous, pale grey to greyish brown, somewhat darker (often reddish) at the centre, the margin often very pale, pallescent when drying. Lamellae 12-20 reaching the stipe, ascending, narrowly adnate, dorsally intervenose with age, whitish, cream to grey, the sides densely punctate with minute, dark red-brown dots (seen under hand lens, but not always easily seen), the edge dark reddish brown. Stipe 20-70 x 1-1.8 mm, hollow, straight to curved, terete, fragile, glabrous except for the pruinose apex, becoming shiny, grey, greyish brown, darker below, the apex whitish to grey; the base covered with white fibrils. Odour nitrous.

Basidia 27-30 x 7-9 µm, clavate, 4-spored, with sterigmata 4-6 µm long. Spores 8-11.5 x 4.5-6 µm, Q 1.5-2, Qav ~1.8, pip-shaped to almost cylindrical, smooth, amyloid . Cheilocystidia 35 - 77 x 10 - 16 µm, smooth, fusiform or clavate, apically generally passing into a simple neck, but also with rounded apex; with reddish contents. Pleurocystidia numerous, similar, but sometimes without coloured contents. Lamellar trama dextrinoid. Hyphae of the pileipellis 2-8 µm wide, covered with simple to branched excrescences 1-30 x 1-3 µm which may form dense masses. Hyphae of the cortical layer of the stipe 2.5-3.5 µm wide, smooth to sparsely covered with simple, cylindrical excrescences 2-8 x 1-2 µm, terminal cells 4-7 µm wide, coarsely diverticulate. Clamp connections present in all tissues.

Microphotos of cheilocystidia

Microphotos of cheilocystidia and hyphae of the pileipellis

The nitrous smell is quite strong and reliable as an identification character. I have not seen the dark red-brown dots on the sides of the lamellae in all collections. They can only be seen under a hand lens and even then they sometimes are hard to discover. The colour of the lamellar edge is not as dark and distinct as in M. rubromarginata, but is always visible. Besides from the smell M. rubromarginata differs in having more broadly pip-shaped spores, and usually it grows on decaying wood.

One should also notice a possible confusion with Mycena olivaceomarginata, which sometimes has a greyish brown pileus with a reddish brown centre as well as a stipe with a dingy whitish apex and greyish brown colours below, and a nitrous smell. The two species can be told apart on account of the cheilocystidia. In M. capillaripes they are smooth while they are more varied in M. olivaceomarginata, often with two or three necks or with several coarse excrescences. The latter also lacks pleurocystidia.

Go to Sect. Rubromarginatae.