Pileus up to 20 x 14 mm when still closed, 20-50 mm when expanded, ellipsoid-ovoid at first, later campanulate, finally applanate or even revolute at deliquescence. Cap cuticle whitish at first, soon with a brown or dark grey-brown disc, then cream-hazelnut coloured, progressively greying, pronouncedly grooved up to the centre, covered with a fibrous-woolly whitish veil, which appears more crowded at the centre, split up toward the periphery in small upturned browning scales. Lamellae fully deliquescent, ascending, free, narrow, very crowded, 2-5 mm high, white at first, then grey and finally blackish, with a lighter, whitish but turning to pink, scurfy edge. Stipe 20-80 x 3-5 mm, up to 8 mm at the base, cylindrical or slightly tapering towards the apex, at first bulbous-clavate, later slightly bulbous, solid, becoming hollow, fully white, thinly striate and vaguely flocculose, provided with a thoroughly differentiated median annulus, white above, cream ochraceous on the lower surface. Context white, quite firm, fibrous, devoid of particular smell and taste.
  Spores [100,5,2] 6.7-9.3 x 5.3-6.8 x 4.7-5.4 µm (L x B x W); Q = 1.20-1.45; av. Q = 1.35; av. L = 8.0-8.4, av. B = 6.0-6.3 µm, submitriform, rhomboid or ovoid and somewhat truncate in frontal view, ellipsoid in side view, dark red-brown, with conspicuous hilar appendage and a distinct, central or slightly eccentric, 1.5-1.8 µm wide germ pore. Basidia 24-43 x 8-10 µm, 4-spored, present in three forms: claviform and short-stalked, cylindrical-clavate or elongated cylindrical with a distinct median narrowing. Each basidium is surrounded by (3-)4-6(-8) pseudoparaphyses. Pleurocystidia and caulocystidia absent. Cheilocystidia 30-65 x 15-23 µm, abundant (edge sterile), polymorphous: (sub)globose, ovoid, ellipsoid, oblong, utriform, subcylindrical. Veil made up of elongate elements in chains, cylindrical or somewhat inflated, often constricted at septum, 30-125 x 6-25 µm, with fusiform, ovoid or cylindrical terminal cells. Pileipellis a cutis, made up of cylindrical, more or less parallel, repent hyphae. Clamp-connections absent. Pseudoclamps present, difficult to observe because of the very thin walls.

Habitat & distribution

  Very rare. Solitary or fasciculate on dung of fallow deer. Only known from the type locality (State of Washington, U.S.A.) and one find from Europe (Italy).

Remarks

  Coprinus spadiceisporus was described by Van De Bogart (l.c.) from Western North America. Recent the species is found in Italy and therefore added to this paper. The given description is based on the Italian material.
  Although the spores are slightly larger in the American material (8.2-10.3 x 5.8-7.3 µm), the other macroscopical and microscopical features are similar in all collections.