Closed pileus up to 16 x 12 mm, ochre-brown to cinnamon-brown at centre (Mu. 10 YR 6-7/6, K. & W. 5B5) paler towards margin, up to c. 20 (-25) mm wide when expanded. Lamellae narrowly adnate, almost free, white to blackish; L. 26-38, l= 0-3. Stipe 30-80 x 1-3 mm, whitish, pubescent.
  Spores [20/1/1] 11.6-15.8 x 6.1-7.9 µm, av. L= 13.8, av. B= 6.9 µm, Q= 1.80-2.00, av. Q= 1.90, ellipsoid to ovoid; germ pore eccentric, c. 1.8 µm wide. Basidia 18-40 x 9-13 µm, 4-spored. Pseudoparaphyses 4-6 per basidium. Cheilocystidia 20-60 x 20-30 µm, (sub)globose, (broadly) ellipsoid, obovoid, but some lageniform cheilocystidia are present as well. Pleurocystidia 60-120 x 20-45 µm, subglobose, broadly ellipsoid, obovoid to broadly cylindrical. Pileocystidia 30-110 x 10-21 µm, lageniform with tapering neck and 4-8 µm wide apex. Sclerocystidia absent. Clamp-connections present.

Habitat

  On cow-dung, but also on decaying straw. Gregarious or more or less fasciculate. Rare.

Remarks

  This species is characterized by the combination of pleurocystidia, four-spored basidia, spores with an eccentric germ pore, clamp-connections and its preference for dung. Coprinus congregatus is probably the closest relative. It differs from C. ephemerus in the absence of clamps and the slightly smaller spores.