Macroscopic features

  Closed pileus ellipsoid to cylindrical-ellipsoid, up to 5 x 3 mm, expanding up to 7 mm broad, in buds dark grey or mouse-grey, becoming paler with age, entirely powdery but at margin somewhat hairy-floccose. Lamellae, L = 8-16, l = 0-1, free, rather distant, first white but soon grey to spotted blackish. Stipe up to 20 x 0.5 mm, vitreous, subbulbous at base. Smell absent.

Microscopic features

  Spores [140,7,6] 6.3-10.3 x 3.8-6.2 µm, Q = 1.34-1.95, av. Q = 1.55-1.80, av. L = 7.4-9.3, av. B = 4.5-5.7 µm, cylindrico-ellipsoid, ellipsoid or ovoid, red-brown under microscope, with central, 1.3 µm wide germ pore. Basidia 12-28 x 7-9 µm, 4-spored, surrounded by (3-)4-5(-6) pseudoparaphyses. Pleurocystidia 50-120 x 21-38 µm, ellipsoid, utriform or subcylindrical. Cheilocystidia 40-90 x 18-32 µm, similar to pleurocystidia. Pileipellis consisting of roundish elements covered by narrow hyphae, passing upwards into velar tissue. Velar elements (sub)globose to ellipsoid, up to 50 µm wide, connected by 10-75 µm long and 3-7 µm wide, cylindrical, sometimes fusiform hyphae, hyaline, greyish in part, thin-walled, granular. Velum at margin of pileus and on stipe made up of cylindrical to fusiform or clavate elements for the most part. Clamp-connections absent.

Habitat & distribution

  Solitary or in groups; on pure dung, especially of cow.

Remarks

  The type of C. poliomallus is lost (H. Romagnesi pers. comm.) Therefore, coll. Uljé 1181 is selected here as neotype.
  Coprinus coniophorus, the only other species in subsect. Nivei with greyish veil, differs from C. poliomallus by the larger basidiocarps, amygdaliform spores, gregarious growth, and the habitat, being on and round rotten wood.