Pileus 20-30 x 15-25 mm when still closed, more or less narrowly conical, expanding to conical and then up to 50 mm wide, at first greyish ochre to ochre-brown, fibrillose-squamulose at centre, later grey-brown and almost smooth. Lamellae, L = > 50, l = 3-7, first white, then greyish-brown to black. Stipe 60-130 x 3-5 mm, white; base clavate.
  Spores 6.0-8.9(-10.6) x 4.1-5.3(-5.7) µm, Q = 1.40-1.85(-2.10), av. Q = 1.55-1.60(-1.90, av. L = 7.4-7.7(-9.3) µm, av. B = 4.4-5.0(-5.2) µm, ellipsoid or ovoid, with rounded base and apex, dark red-brown; germ pore central, 1.1-1.2 µm wide. Basidia 14-26 x 6.5-8 µm, 4-spored, surrounded by 3-5(-6) pseudoparaphyses. Pleurocystidia 80-140 x 18-28 µm, rather narrowly cylindric or slightly utriform. Cheilocystidia 60-100 x 18-28 µm, similar to pleurocystidia. Elements of veil not studied. Clamp-connections present.

Habitat & distribution

  On stumps of broad-leaved trees or wood-chips, fasciculate. Distribution indistinct, rather rare in the Netherlands.

Remarks

  Characters to differ C. acuminatus from C. atramentarius are the ochre-brown colour, the more conical shape of the usually smaller basidiocarps and the somewhat narrower spores.