Coprinopsis nivea
Description
Coprinellus niveus (Coprinus nivea) is a species of fungus from the family Psathyrellaceae. Cap is conical, expanding with age, becoming flattened, whitish, and covered with white floccules when young, to about 3 cm across.
This medium to medium-large mushroom grows on dung, primarily of cattle. The white veil material is powdery due to the spherical shape of many of the cells that make it up. Other dung-loving ink-caps are either not white or are smaller, so this is an easy species to identify. Although C. nivea is edible and is substantial enough to be a candidate for the table, it rarely is found in quantity and its substrate is off-putting to many.
The striking white color of Coprinopsis nivea sets it apart from numerous other coprinoid fungi found on cow and horse dung.
Besides color, important field marks 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.
Common names: Snowy Inkcap.
Mushroom Identification
Pileus
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 the stipe, maturing upturned to recurved, often radially split and eroded from deliquescing gills; surface dry, white, ash-gray at the margin, covered with mealy-granulose universal veil fragments; context membranous; odor and taste not distinctive.
Lamellae
Gills crowded, free to narrowly attached, white, soon blackening, the edges first, then the faces; lamellulae in two series.
Stipe
Stipe 30-90 x 2-5 mm in width, cylindrical, more or less equal, hollow, fragile, sometimes with an enlarged pointed base; the surface of apex white, striate-tomentose, a lower region with scatted raised fibrils and tomentum; partial veil absent.
Spores
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.
Habitat
Solitary, scattered, or in small groups on the well-decayed horse and cow manure; fruiting year-round after periods of moisture; occasional to locally common.
Look-Alikes
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Is larger and lacks the white granular cap covering.
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Has a granular cap but is reddish-brown and grows on buried wood and at the base of tree stumps.
History
The Snowy Inkcap was described scientifically in 1801 by Christiaan Hendrik Persoon, who named it Agaricus niveus. The great Swedish mycologist Elias Magnus Fries transferred this species to the genus Coprinus in 1838, and there as Coprinus niveus it rested largely undisturbed until DNA analysis by Redhead, Vilgalys & Moncalvo resulted, in 2001, in the genus Coprinus being reduced to very few species. Most of the inkcaps, including the Snowy Inkcap, are now in new genera sited within the family Psathyrellaceae.
Synonyms of Coprinopsis nivea include Agaricus niveus Pers., Coprinus niveus (Pers.) Fr., and Coprinus latisporus P.D. Orton.
The generic name Coprinopsis indicates that this mushroom genus is similar to the genus Coprinus, which means 'living on dung' - that's true of quite a few of the inkcaps and particularly apt for this species. The specific epithet nivea comes from the Latin word for snowy - niveus.
Common names change with time and location. In America, the terms Inky Cap or Inky-cap are most commonly used, while in many older field guides published in Britain you are likely to see Ink Cap or Ink-cap rather than Inkcap.
Photo sources:
Photo 1 - Author: Kathleen Dobson (CC BY-SA 4.0)
Photo 2 - Author: Chaz (chazwt@gmail.com) (CC BY-SA 3.0)
Photo 3 - Author: Michel Langeveld (CC BY-SA 4.0)
Photo 4 - Author: Ron Pastorino (Ronpast) (CC BY-SA 3.0)
