Pileus 15-30 x 6-18 mm when still closed, 45 mm when expanded, oblong, often somewhat conical, first covered with a layer of white, woolly-felty veil, breaking up in patches, later often cream or ochre-brown coloured. Lamellae, L = 60-80, l = 1-5, free, first white to beige, then grey-brown to dark grey, finally black. Stipe up to 120 x 2-6 mm, white, greyish white, minutely fibrillose-floccose, later glabrous; base slightly bulbous and white felty.
Spores [80,3,4] 9.0-12.7 x 8.2-11.7 µm, subglobose or broadly ellipsoid, sometimes with slightly apical papilla, slightly narrower in side view (c. 0.5 µm), rounded at apex, dark red-brown, with central to slightly eccentric, c. 1.6 µm wide germ pore, which is often difficult to observe; Q = 1.00-1.25, av. Q = 1.05-1.15; av. L = 10.9-11.3, av. B = 9.5-10.7 µm. Basidia 16-32 x 9-13 µm, 4-spored, surrounded by 5-7(-8) pseudoparaphyses. Pleurocystidia 60-200 x 20-26(-40) µm, (narrowly) utriform, (sub)cylindrical, lageniform or conical. Cheilocystidia 50-120 x 20-32 µm, (narrowly) utriform, (sub)cylindrical, (narrowly) conical or sublageniform. Elements of veil thin-walled, diverticulate, 3-10(-18) µm wide. Clamp-connections absent.
Habitat & distribution
In small groups, a few together on straw (gh), rice-straw (Japan) and on rotting material made up of natural materials like coconut mattings, lime ceilings mixed with straw, cotton textiles, etc. Rare. Europe, Canada, Japan. In Western Europe in most cases indoors and in greenhouses.
Coprinus kimurae can be recognised by the subglobose to broadly ellipsoid spores, the absence of clamp-connections, the rather large basidiocarps, the veil breaking up in patches (similar to C. picaceus) and the habitat.
Considering the occurrence indoors in (heated) greenhouses, and outdoors in places like compost heaps and on rotten coconut-fibre fabric, it is likely that Coprinus kimurae is a thermophilic fungus. In the Netherlands it is found in greenhouses, although the species has been found outdoors on a coconut matting (in a sheltered garden) and there is one recording from a compost heap, which probably was in a greenhouse.
In earlier publications (Uljé, 1995: 11 and Arnolds et al., 1995: 119) the first author considered that C. kubickae was synonymous with C. kimurae, but further study has indicated that this opinion was wrong. Coprinus kubickae is a very small species with veil breaking up in very small flocks and not in patches, with on average somewhat smaller spores, narrower elements of veil, presence of clamp-connections and a habitat which is clearly different.