Cap 4.0-9.0 cm broad, convex, expanding to plano-convex at maturity, sometimes with a broad umbo; margin decurved when young, frequently decorated with veil fragments; surface moist, disc matted-tomentose, dull-tawny-brown, becoming fibrillose, squamulose to squamose near the margin, the ornamentation buff to dark-brown; context cream-white, firm, up to 1.0 cm thick at the disc, unchanging or darkening slightly; odor aromatic, pungent, like that of Suillus pungens.
Gills adnate with a descending tooth, seceding in age, relatively broad, dark-brown at maturity, edges fimbriate, lighter than the faces, (use hand lens); lameullae 3-4 seried.
Stipe 6.0-13.0 cm long, 0.8-1.6 cm thick, more or less equal, sometimes with a basal bend, hollow at maturity; apex white fibrillose-striate (remnants of gill edges), lower portion covered with buff to dark-brown scales over a pallid background; partial veil forming a fibrillose annular zone high on the stipe.
Spores 7.0-8.5 x 4.0-4.5 µm, broadly ellipsoid in face-view, strongly inequilateral in profile (shaped like an orange wedge), smooth to occasionally very minutely roughened, germ pore present, hilar appendage indistinct; spore print blackish-brown.
Solitary to clustered in mixed hardwood-conifer woods; fruiting from after the fall rains to mid-winter; uncommon.
Psathyrella echiniceps is recognized by a scaly cap, often hung with veil fragments, and squamose stipe. Also found in California are Psathyrella longistriata and P. velutina, two species which are similar in size and stature. Psathyrella longistriata is distinguished by a well developed striate annulus, while P. velutina has a dull reddish-brown to ochre-brown, more fibrillose cap, and larger, roughened spores.