Closed pileus up to 10 x 8 mm, first red-brown (Mu. 5 YR 2.5/2, 3/4, K.& W. 6E6), than somewhat more dull brown (Mu. 7.5 YR 4/6 to 5-6/4, K.& W. 6D/E6), finally more greyish brown (Mu. 10 YR 5-6/3-4) to greyish; expanded pileus up to 20 mm wide. Veil present on pileus visible as small, whitish, radial fibrillose flocks. Lamellae narrowly adnate, relative distant, first white, soon dark brown to blackish; L = 9-18, l = 0-3. Stipe 20-50 x 0.5-1.5 mm, at base up to 2 mm wide, whitish, pubescent from setulae.
  Spores [180,9,9] 8.5-10(-12) x 5-6 µm, av. L= 8.8-9.6, av. B= 5.3-5.6 µm, Q= 1.55-1.80, av. Q= 1.65-1.70, ovoid; germ pore slightly eccentric to almost central, c. 1.5 µm wide. Basidia 16-30 x 6-9 µm, 4-spored. Number of pseudoparaphyses 3-5 per basidium. Cheilocystidia 20-45 x 9-13 µm, lageniform with rather thick, tapering to cylindrical neck and in part somewhat enlarged apex, 3-6 µm wide. Pleurocystidia absent. Pileocystidia lageniform, 50-110 x 11-20 µm, usually with slightly enlarged, subclavate, 6-11 µm wide apex. Sclerocystidia absent. Veil on pileus consisting of cylindrical, somewhat diverculate, thin-walled, in part slightly thick-walled (< 1 µm, seldom up to 1.5 µm thick) hyphae with often clavate, up to 7 µm thick terminal cells, usually with granular incrustations. Clamp-connections present.

Habitat

  On naked, often mossy soil and on mossy branches. Subgregarious. Rather common.

Remarks

  This species can be distinguished from C. hiascens and C. spec. Uljé 926 by its spores with a slightly eccentric germ pore. C. hiascens has tapering pileocystidia whereas C. heterotrix has not and Uljé 926 posseses vesiculose cheilocystidia, by which character also C. velatopruinatus deviates from C. heterothrix. Coprinus spec. Uljé 952, another species with cylindrical velar elements differs in subcylindrical, more slender spores and differently shaped velar elements. The lamellae are rather distant in C. heterothrix; this is probably a useful taxonomic character.