Coprinopsis nivea
Taxon 50(1): 229. 2001.
Common Name: none
Synonym: Coprinus niveu (Pers.) Fr.
Cap at first conic-ellipsoid, 10-15 mm broad, expanding up to 35 mm, in age broadly conic, campanulate to plane with a central umbo; margin incurved when young, weakly striate, tight to stipe, maturing upturned to recurved, often radially split and eroded from deliquescing gills; surface dry, white, ash-grey at the margin, covered with mealy-granulose universal veil fragments; context membranous; odor and taste not distinctive.
Gills crowded, free to narrowly attached, white, soon blackening, the edges first, then the faces; lamellulae in two series.
Stipe 30-90 x 2-5 mm in width, cylindrical, more or less equal, hollow, fragile, sometimes with an enlarged pointed base; surface of apex white, striate-tomentose, lower region with scatted raised fibrils and tomentum; partial veil absent.
Spores 11 x 15.5 x 9-12 µm; smooth, in face-view lemon to heart shaped, sometimes weakly angular, in profile ellipsoid 7.5-9 µm in width; germ pore central to slightly eccentric; pileal sphaerocysts thin-walled, often partially collapsed, globose to ovoid 37-90 µm in width; spores blackish in deposit.
Solitary, scattered, or in small groups on well decayed horse and cow manure; fruiting year-round after periods of moisture; occasional to locally common.
Unknown, probably edible, but unsubstantial.
The striking white color of Coprinopsis nivea sets it apart from numerous other coprinoid fungi found on cow and horse dung. Besides color, important fieldmarks include moderate size and a conic cap covered with mealy-granulose veil fragments. Like most coprinoid mushrooms, the gills and cap of Coprinopsis nivea blacken and deliquesce with age, but not dramatically in this species. Microscopically it is distinguished by thin-walled, globose pileal veil cells that glisten in the proper light much like those of Coprinellus micaceus, (use hand lens) and relatively large spores that are lemon to heart-shaped in face-view. Other dung inhabiting inky caps that are somewhat similar include Coprinus sterquilinus, a look-alike version of the shaggy mane Coprinus comatus but smaller, and members of the Coprinopsis radiata, C. lagopus, C. macrocephala group, all of which have greyish caps adorned with wooly flocks. These species, including Coprinopsis nivea, are cosmopolitan in distribution, not surprising considering their dung habit and the global movement of grazing animals.
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