Hygrocybe

Hygrocybe
File:Hygrocybe coccinea and Hygrocybe virginea Rosemary Winnall.JPG
The scarlet H. coccinea and Cuphophyllus virgineus, Wyre Forest, UK
Scientific classification
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Hygrophoraceae
Genus:	Hygrocybe (Fr.) P.Kumm. (1871)
Type species
Hygrocybe conica (Schaeff.) P.Kumm. (1871)
Synonyms
Godfrinia Maire (1902) Bertrandia R.Heim (1936) Pseudohygrocybe (Bon) Kovalenko (1988)

Hygrocybe is a genus of agarics (gilled fungi) in the family Hygrophoraceae. Called waxcaps in English (sometimes waxy caps in North America), basidiocarps (fruit bodies) are often brightly coloured and have waxy to slimy caps, white spores, and smooth, ringless stems. In Europe they are characteristic of old, unimproved grasslands (termed waxcap grasslands) which are a declining habitat, making many Hygrocybe species of conservation concern. Elsewhere they are more typically found in woodlands. Most are ground-dwelling and all are believed to be moss associates. Around 150 species are recognized worldwide. Fruit bodies of several Hygrocybe species are considered edible and are sometimes offered for sale in local markets.

Taxonomy

History

Hygrocybe was first published in 1821 by Swedish mycologist Elias Magnus Fries as a subsection of Agaricus and in 1871 was raised to the rank of genus by Kummer. In several papers, Karsten and Murrill used the name Hydrocybe, but this is now taken as an orthographic variant of Hygrocybe. The generic name is derived from the Greek ῦγρὁς (= moist) + κυβη (= head).

Despite its comparatively early publication, the genus Hygrocybe was not widely accepted until the 1970s, most previous authors treating it as a synonym of Hygrophorus, a related genus of ectomycorrhizal agarics.

Hygrocybe itself has been split into subgenera, several of which – notably Cuphophyllus (= Camarophyllus sensu Singer, non Fries) and Gliophorus Herink – have subsequently been raised to generic rank. Some species, such as the mauve splitting waxcap (Humidicutis lewelliniae), have been described in the small genus Humidicutis.

Current status

Recent molecular research, based on cladistic analysis of DNA sequences, suggests that Hygrocybe as currently understood is paraphyletic and does not form a single clade within the Hygrophoraceae. As a result, the genus Cuphophyllus (comprising Hygrocybe pratensis and its allies) was removed from Hygrocybe sensu stricto, together with the genus Gliophorus (comprising Hygrocybe psittacina and its allies).

Description

Fruit bodies of Hygrocybe species are all agaricoid, most (but not all) having smooth to slightly scaly caps that are convex to conical and waxy to slimy when damp. Many (but not all) are brightly coloured in shades of red, orange, or yellow – less commonly pink or green. Where present, the gills beneath the cap are often equally coloured and usually distant, thick, and waxy. One atypical South American species, Hygrocybe aphylla, lacks gills. The stems of Hygrocybe species lack a ring. The spore print is white. Fruit bodies of some species, notably Hygrocybe conica, blacken with age or when bruised. Microscopically, Hygrocybe species lack true cystidia and have comparatively large, smooth, inamyloid basidiospores.

Habitat, nutrition, and distribution

Most species of Hygrocybe are ground-dwelling, though a few (such as Hygrocybe mexicana and H. rosea) are only known from mossy tree trunks or logs. In Europe, species are typical of unimproved (nutrient-poor), short-sward grasslands, often termed "waxcap grasslands", but elsewhere they are more commonly found in woodland.

Their metabolism has long been debated, but recent research shows that they are neither mycorrhizal nor saprotrophic. It seems they may be symbiotically associated with mosses, as suggested by several earlier authors.

Species are distributed worldwide, from the tropics to the sub-polar regions. Around 150 have been described to date.

Conservation

Main article: Waxcap grassland

In Europe, waxcap grasslands and their associated fungi are of conservation concern, since unimproved grasslands (formerly commonplace) have declined dramatically as a result of changes in agricultural practice. As a result, by 1993, 89% of European Hygrocybe species appeared on one or more national red lists of threatened fungi. In several countries, action has been taken to conserve waxcap grasslands and some of the rarer Hygrocybe species. In the United Kingdom, some grasslands have gained a measure of legal protection as Sites of Special Scientific Interest because of their waxcap interest.

Economic usage

Because Hygrocybe species cannot be maintained in culture, none is cultivated commercially. Fruit bodies of a few species are considered edible in eastern Europe, south-east Asia, and Central America and are collected and consumed locally.

Literature

No comprehensive monograph of the genus has yet been published. In Europe, however, species of Hygrocybe have been illustrated and described in a standard English-language guide by Boertmann (2010) and also (together with Hygrophorus) in an Italian guide by Candusso (1997). European species have also been covered, more briefly, in descriptive French keys by Bon (1990). Dutch species were illustrated and described by Arnolds (1990). No equivalent modern guides have been published for North America, the most recent being by Hesler & Smith (1963). There is, however, a guide to Californian species by Largent (1985). In Australia, Hygrocybe species have been illustrated and described by Young (2005) and in New Zealand by Horak (1990).

Species

Main article: List of Hygrocybe species

• 2011-06-17 Hygrocybe cantharellus 69428 cropped.jpg

  Hygrocybe cantharellus
• 2011-03-08 Hygrocybe flavescens 64217.jpg

  Hygrocybe flavescens
• Hygrocybe conica - geograph.org.uk - 240361.jpg

  Hygrocybe conica

External links

• Hygrocybe in Index Fungorum
• WaxCap Website, University of Wales, Aberystwyth