Closed pileus up to 18 x 14 mm, cream-coloured with ochre-brown to cinnamon-coloured centre (Mu. 7.5 YR 4/6, K. & W. 6E6) when young, at mature greyish-yellow (Mu. 10 YR 7/6, K. & W. 4A/B4), c. 25 mm in diam. when expanded. Lamellae narrowly adnate to almost free, narrow, white to blackish; L= 18-34, l= 0-3. Stipe 30-80 x 0.5-2.5 mm, whitish, pubescent.
  Spores [40,2,2] 9.8-14.2 x 5.6-7.5 µm, av. L= 11.1-12.4, av. B= 6.1-7.0 µm, Q= 1.55-1.95, av. Q= 1.75-1.85, ellipsoid to ovoid; germ pore strongly eccentric, c. 1.8 µm wide. Basidia 16-36 x 9-12 µm, 4-spored. Pseudoparaphyses (3-)4-5(-6) per basidium. Cheilocystidia 30-90 x 20-45 µm, ellipsoid to broadly utriform. Pleurocystidia 30-140 x 20-50 µm, ellipsoid, oblong to slightly utriform. Pileocystidia 30-120 x 8-18 µm, lageniform with tapering neck and 3-8 µm wide apex. Sclerocystidia absent. Clamp-connections absent.

Habitat

  Gregarious on dung, especially dung mixed with straw. Common.

Remarks

  Coprinus congregatus is very similar to C. ephemerus. It seems to differ from that species practically only in the absence of clamps and the somewhat smaller spores (9.8-14.2 x 5.6-7.5 µm versus 11.6-15.8 x 6.1-7.9 µm).