Pileus 7-10 x 4-5.5 mm when still closed, up to 18 mm when expanded, subglobose, ellipsoid, ovoid, first white with somewhat greyish centre, soon more grey. Veil white to grey, radially splitting up in small, hairy floccose scales. Lamellae, L = 26-28, l = 0-3, rather crowded, free, first white, then greyish, finally blackish; Stipe up to 100 x 1-1.5 mm, whitish, at base somewhat clavate.
  Spores [40,2,1] 6.7-8.7 x 4.8-6.3 µm, cylindrical-ovoid, rounded rectangular in most cases, rather truncate, very dark red-brown, with central, c. 1.8 µm wide germ pore; Q = 1.30-1.60, av. Q = c. 1.45; av. L = 7.9-8.3, av. B = 5.5-5.6 µm. Size of basidia not noted, 4-spored. Pleurocystidia 80-135 x 20-30 µm, subcylindrical or oblong, often conical. Cheilocystidia 50-100 x 15-25 µm, similar to pleurocystidia. Elements of veil thin-walled, diverticulate, 2-7(-10) µm wide, slightly incrusted. Clamp-connections probably present.

Habitat & distribution

  In small groups on dung of herbivores. Very rare. Not known from the Netherlands. Recorded from England, Ireland and Scotland according to Orton & Watling (1979: 51).

Remarks

  The presence of clamp-connections could not be verified with certainty because of the bad condition of the type material. Coprinus filamentifer can readily be recognized by the subcylindrical spores and coprophilous habitat.