Coprinellus heptemerus (M. Lange & A.H. Sm.) Vilgalys, Hopple & Jacq. Johnson

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

Coprinellus heptemerus forma parvisporus, New Forest, Hampshire

The fine details of small inkcap mushrooms require close examination, and with species that grow on dunga close encounter is not something that everyone wants to experiemce. An alternative strategy is to carry with you a pair of binoculars - as many people interested in butterflies and mohts do - and to focus in from a distance of a mtre or two. With Coprinellus hepteremus the distinguishing features require far more magnification than can be achieved with binoculars, however, and so a fairly high-powered microscope is nessary.

Distribution

Uncommon in Britain and Ireland, this little inkcap occurs throughout most of mainland Europe; it is also reported to occur in some countries in northern Asia including Japan, as well as in many parts of North America.

Coprinellus heptemerus, cap rim, New Forest, Hampshire

Taxonomic history

This inkcap mushroom was described scientifically in 1952 under the name Coprinus heptemerus by Danish mycologist M. Lange (1919 - 2003) and Americanmycologist Alexander Hanchett Smith (1904 - 1985). That name remained in general use until 2001 when, as a result of molecular (DNA) analysis, the Coprinus genus was shown to contain groups of fungi with only distant relationships to one another, and the earlier Coprinus group was dismantled with this little Inkcap being moved into the genus Coprinellus. (Coprinus comatus, the Shaggy Inkcap, plus three other rare fungi are all that remains in the formerly large Coprinus genus.)

Synonyms of Coprinellus heptemerus include Coprinus curtus f. macrosporus Romagn., Coprinus heptemerus M. Lange & A.H. Sm., and Coprinus heptemerus f. heptemerus M. Lange & A.H. Sm.

Etymology

The generic name Coprinellus indicates that this mushrooms genus is (or was thought to be) closely related to or at least similar to fungi in the genus Coprinus, which literally means 'living on dung' - that's true of quite a few of the inkcaps but not particularly apt for this and several other Coprinellus species. The suffix -ellus indicates fungi that produce rather smaller fruitbodies than those of Coprinus species. The specific epithet impatiens comes directly from the Latin word for 'impatient' or 'intolerant' and may refer to the texture of these fungi which crumble easily if touched.

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 Coprinellus heptemerus

Cap

Initially oval to conical or cylindrical, 5-9 x 3-9mm, expanding to campanulate and becoming radially grooved; buff at first, turning grey or black from the margin.

Gills

Adnexed or free; moderately spaced to distant; initially whitish, turning black and sometimes deliquescing.

Stem closeup, Coprinellus heptemerus

Stem

1 to 5cm long and 0.5 to 1mm in diameter; translucent or white; downy.

Pileocystidia of Coprinellus heptemerus

Pileocystidia

Show larger image

Spores of Coprinellus heptemerus

Spores

Ellipsoidal, smooth, 12.5-16.5 x 7-8.5µm; with an eccentric germ pore.

Note: The spores shown here correspond to what some authorities refer to as Coprinellus heptemerus f. parvisporus, whose spores fall within the range 10-12 x 6-8μm; this small-spored form is recorded from Britain, Spain and Italy.

Show larger image

Spore print

Very dark brown, almost black.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic, appearing on dung.

Season

Mainly spring to autumn, but these coprophilous inkcaps can fruit at any time of year except during heavy frosts.

Similar species

Coprinopsis nivea occurs in similar habitats; it is a more common and significantly larger inkcap.

Culinary Notes

Coprinellus heptemerus grows on dung and should therefore be treated as 'suspect'. It is much too small to be considered as one for the pot!

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.

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

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.

Acknowledgement

Pictures on this page were kindly contributed by David Kelly.

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