Psathyrella calcarea

Fruiting on calcareous soils among leaf litter, with a campanulate to convex pileus 0.5 to 1.5 cm across, strongly hygrophanous, dark brown when moist, fading to pale brown when dry, greyish-brown lamellae from sporulation, and a cylindrical, fragile stipe with whitish superficial fibrils.

Pileipellis composed of a layer of subglobose, clavate to pyriform cells 20 to 35 µm in diameter, overlying parallel filamentous hyphae with short cells, 5 to 20 µm wide.

Caulocystidia present at the stipe apex, predominantly lageniform, arranged in tufts/fascicles.

Cheilocystidia fusiform to lageniform, hyaline, 25 to 60 µm long and 9 to 18 µm wide, intermixed with short, clavate to pyriform hyaline cells.

Pleurocystidia clavate to lageniform, hyaline, 60 to 75 µm long and 13 to 15 µm wide.

Basidia clavate, 20 to 25 µm long, 10 to 13 µm wide, clamped at the base, 4-spored.

Spores ellipsoidal, smooth-walled, very dark brown under the microscope, large, 13 to 19 µm long, 7 to 10 µm wide, with a tiny, slightly eccentric hyaline apiculus at one end and a central germ pore at the other.