Coprinopsis nivea (Pers.) Redhead, Vilgalys & Moncalvo - Snowy Inkcap

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Psathyrellaceae

Coprinellus nivea - Snowy Inkcaps

Coprinopsis nivea (syn. Coprinus niveus) is a rather fragile inkcap species with a chalky coating (velar remains) on the caps and stems of young specimens. Initially white, the gills autodigest as the fruitbody ages.

The Snowy Inkcap is a dung-loving mushroom, and most often it is found on old horse dung or on cow dung, particularly where dung and straw from stables or from cow sheds has been piled up and left to rot.

Toxicity

The Snowy Inkcap is variously reported as either poisonous or at least 'suspect'. Because it has toxic close relatives - for example the Magpie Inkcap, Coprinopsis picacea - it seems unwise to take risks with what are, after all, insubstantial toadstools that rarely occur in large numbers. Need further convincing? They grow on animal dung... and if you believe that the maxim 'you are what you eat' applies to fungi, then... enough said, surely!

Distribution

An infrequent but far from rare find in all parts of Britain and Ireland, the Snowy Inkcap occurs throughout Scandinavia and many other northern countries of mainland Europe but is reported only rarely from southern European countries. This inkcap is also found in some parts of North America.

Taxonomic history

The Snowy Inkcap was described scientifically in 1801 by Christiaan Hendrik Persoon, who named it Agaricus niveus. (Most gilled fungi were initially dumped into a gigantic Agaricus genus.) 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.

Etymology

The generic name Coprinopsis indicates that this mushrooms genus is similar to the genus Coprinus, which literally 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.

Identification guide

Cap of Coprinopsis nivea - Snowy Inkcap, by Dave Kelly

Cap

As in the immature specimen illustrated here, the cap is initially egg-shaped, like many of the inkcap mushrooms. Later it expands to become bell shaped, sometimes opening out like an umbrella and occasionally splitting at the margin.

A distinctive white, mealy covering of tiny veil fragments adheres to the cap, which is 2 to 5cm in diameter at maturity.

Gills

The free gills of the Snowy Inkcap are initially white, becoming grey and eventually black as they begin deliquescing (turning into a black inky liquid).

Stem

4 to 7mm diameter and up to 9cm tall, the white stems are cylindrical with a slight thickening at the base, which is covered in cottony fibres.

 

Spores

Ellipsoidal to lemon shaped, smooth, 14-19 x 11-13µm.

Spore print

Black.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic, on cow dung, horse dung and manured rotting straw.

Season

May to November in Britain.

Similar species

Coprinopsis atramentarius is larger and lacks the white granular cap covering.

Coprinellus micaceus has a granular cap but is reddish-brown and grows on buried wood and at the base of tree stumps.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Orton, P.D. & Watling, R. (1979). British Fungus Flora: Agarics and Boleti. Vol 2. Coprinaceae: Coprinus. Royal Botanic Garden: Edinburgh.

Redhead SA, Vilgalys R, Moncalvo J-M, Johnson J, Hopple JS Jr.; Vilgalys, Rytas; Moncalvo, Jean-Marc; Johnson, Jacqui; Hopple, Jr. John S (2001). 'Coprinus Pers. and the disposition of Coprinus species sensu lato.'. Taxon (International Association for Plant Taxonomy (IAPT)) 50 (1): 203–41.

English Names for fungi; British Mycological Society, 2013.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

Acknowledgements

This page includes photographs that are shown with the kind permission of David Kelly.

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