Densely cespitose on fern rhizomes, mainly of Athyrium filix-femina. Autumn. Known from Austria, Belgium, Finland, Germany (rare and threatened), Norway, Sweden and Switzerland. It is nowhere connom and is rarely recorded. Rare in Norway but probably overlooked. See also Redhead (1984).

Pileus 3-7 mm across, parabolical, campanulate, broadly conical, with a small papilla or somewhat truncate, shallowly sulcate, translucent-striate, glabrous, pale brown to whitish, often with a dark brown centre and pallid to white margin. Lamellae 14-17 reaching the stipe, ascending, broadly adnate to somewhat decurrent, white, the edge concave to horizontal, concolorous. Stipe 20-50 x 0.5-1 mm, equal or somewhat broader at the apex, straight to curved, glabrous, cartilaginous, pale yellow-brown, whitish apex and darker below, the base covered with long, coarse fibrils. Odour none. Taste none (Ludwig 2012).

Basidia 16-27 x 7-9 µm, clavate, 4-spored. Spores 7.5 - 9.8 x 4.5 -5.7 µm, Q 1.3-1.8, qav = 1.5, broadly pip-shaped, smooth, amyloid. Cheilocystidia 15-33 x 8-17 µm, forming a sterile lamellar edge, clavate to obpyriform, apically covered with cylindrical excrescences 0.5 - 7 x 0.5-0.8 µm. Pleurocystidia absent. Hyphae of the pileipellis 1-12 µm wide, densely covered with cylindrical excrescences 1-7 x 0.5-0.8 µm, terminal cells clavate, diverticulate. Hyphae of the cortical layer of the stipe 1 - 5 µm wide, smooth to sparsely covered with minute warts to cylindrical excrescences 0.5-4 x 0.5 µm, terminal cells clavate, diverticulate. Clamp connections present but not always easy to detect.

See further microscopic figures.

The macroscopic description is based on one Norwegian collection (Aronsen A 59/94), and the microscopic description refers to one Swedish and some Norwegian collections.

Mycena lohwagii is a member of sect. Polyadelphia where it occupies an unique position in the way the stipe is attached to the substratum, that is, neither by radiating mycelial filaments nor by being insititious, but by long and coarse fibrils (Maas Geesteranus, 1982: 268). It is readily identified by the occurence on fern rhizomes, the pale colour of the pileus, the broadly adnate attachment of the lamellae, and the cheilocystidia with fairly short cylindrical excrescences.

Mycena pterigena, also growing on ferns, where it can be found together with M. lohwagii, is a more diminutive species with reddish to pink colours of the pileus, the lamellar edge and the stipe. It may, however, occur in white, albino forms. The differences between M. lohwagii and albino M. pterigena are tabulated below.

Go to key to sect. Polyadelphia.