Tephrocybe rancida

Under broadleaf trees or conifers, preferring acidic soils, with a hemispherical to convex pileus retaining a central umbo, 2 to 4 cm in diameter, fibrillose greyish-brown surface, virtually free ochre-grey lamellae, cylindrical greyish stipe with whitish pruina, strong rancid-farinaceous odor, and farinaceous taste.

Cuticle filamentous, composed of thin-walled hyphae arranged more or less parallel to only very slightly interwoven, 3 to 7 µm wide, with slight greyish pigment inside, septate and with septa partially clamped.

Lamellar edge fertile, without elements differentiated from basidia or basidioles.

Lamellar trama regular to parallel.

Basidia cylindric-clavate, 25 to 30 µm long, 5 to 7 µm wide, with abundant siderophilous granulation inside, basal clamp connections, mostly 4-spored.

Spores ellipsoid, smooth, hyaline, thin-walled, slightly pointed at the end bearing the apiculus, 6 to 8.5 µm long, 3.5 to 4.5 µm wide, with oil droplets of various sizes inside, inamyloid in Melzer's reagent.