Cap 0.7-3.0 cm broad, conic becoming bell-shaped, often with a distinct umbo; margin faintly striate at first, conspicuously so in age, often slightly radially furrowed; surface dry, smooth, dark-purple at the disc shading to lilac-brown at the margin; flesh thin, pallid, sometimes pale-vinaceous below the cuticle, unchanging; odor and taste mild.
Gill adnate, moderately broad, close to crowded, white, pallid to pale grey in age, the edges vinaceous-purple.
Stipe 3-7 cm tall, 1-4 mm thick, fragile, thin, hollow; equal to tapering to a slightly enlarged base; sparsely pruinose, especially at apex, soon smooth or polished, occasionally faintly longitudinally striate, pale vinaceous-brown above, darker at the base; cortex flesh lilac-brown, unchanging; veil absent.
Spores 7-10 x 5-6 µm, broadly elliptical, smooth, nonamyloid; spore print white.
Several to clustered on partially buried cones of pines, especially Monterey pine (Pinus radiata); occasional on woody debris; fruiting from late fall to mid-winter.
Unknown; too small to be of culinary value.
This cone-dwelling Mycena is characterized by a purple-brown, bell-shaped cap, vinaceous-purple, marginate gills, and non-bleeding stipe. Look-alike Mycenas with marginate gills include a form of Mycena haematopus which can be distinguished by a lignicolous habit (but rarely cones), stipe that bleeds a reddish juice, and a cap with a scalloped margin. Another species, Mycena californiensis (formerly known locally as M. sanguinolenta) is found in oak duff, has a brighter colored cap (orange-brown), a stipe that bleeds a reddish juice, and a oak duff habit. Mycena elegantula, a name that has been used in the past for cone-inhabiting Mycenas is a synonym of Mycena californiensis.