|The scarlet H. coccinea and the white H. virginea, Wyre Forest, UK|
(Fr.) P.Kumm. (1871)
(Schaeff.) P.Kumm. (1871)
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.
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) – have subsequently been raised to generic rank. As of 2011, however, most standard authorities place these split genera in synonymy with Hygrocybe. Some species, such as the mauve splitting waxcap (Humidicutis lewelliniae), have been described in the small genus Humidicutis.
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, it has been suggested that at least the genus Cuphophyllus (comprising Hygrocybe pratensis and its allies) should be recognized and removed from Hygrocybe sensu stricto, together with the genus Gliophorus (comprising Hygrocybe psittacina and its allies). As yet, however, only a few species of Hygrocybe have been sequenced and though these suggestions have been accepted in principle (e.g. by Boertmann, 2010), they have not yet been widely implemented.
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.
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.
Fruit bodies of one of the commoner European waxcap species, Hygrocybe pratensis, are edible and widely collected, sometimes being offered for sale in local markets. Because Hygrocybe species cannot be maintained in culture, none is cultivated commercially. Fruit bodies of a few additional species are considered edible in eastern Europe, south-east Asia, and Central America and are collected and consumed locally.
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).
- Rea C. (1922). British Basidiomycetaceae: A Handbook of the Larger British Fungi. Cambridge, UK: Cambridge University Press. p. 799.
- Cornelis, Schrevel (1826). Schrevelius' Greek lexicon, tr. into Engl. with numerous corrections. pp. 184–186. Retrieved 2011-10-04.
- Hesler LR, Smith AH. (1963). North American species of Hygrophorus. University of Tennessee Press. p. 416.
- "Hygrocybe (Fr.) P. Kumm.". Index Fungorum. CAB International. Retrieved 2011-09-22.
- "Hygrocybe (Fr.) P. Kumm.". MycoBank. International Mycological Association. Retrieved 2011-09-22.
- Boertmann D. (2010). The genus Hygrocybe (2nd ed.). Copenhagen: Danish Mycological Society. p. 200. ISBN 978-87-983581-7-6.
- Kovalenko AE, Moncalvo J-M, Vilgalys R, Petersen RH, Hughes KW, Lodge DJ. (2002). "Recent advances in molecular phylogeny of temperate Hygrophoraceae and concordance with morphology and ecology (abstract)". IMC7 Abstracts (146).
- Matheny PB, Curtis JM, Hofstetter V, Aime MC, Moncalvo JM, Ge ZW, Slot JC, Ammirati JF, Baroni TJ, Bougher NL, Hughes KW, Lodge DJ, Kerrigan RW, Seidl MT, Aanen DK, DeNitis M, Daniele GM, Desjardin DE, Kropp BR, Norvell LL, Parker A, Vellinga EC, Vilgalys R, Hibbett DS. (2006). "Major clades of Agaricales: a multilocus phylogenetic overview" (PDF). Mycologia 98 (6): 982–95. doi:10.3852/mycologia.98.6.982. PMID 17486974.
- Babos M, Halász K, Zagyva T, Zöld-Balogh Á, Szegő D, Bratek Z. (2011). "Preliminary notes on dual relevance of ITS sequences and pigments in Hygrocybe taxonomy". Persoonia 26: 99–107. doi:10.3767/003158511X578349.
- Læssøe T, Boertmann D. (2008). "A new alamellate Hygrocybe species from Ecuador". Mycological Research 112: 1206–1209. doi:10.1016/j.mycres.2008.04.002.
- Lodge DJ, Matheny PB, Cantrell SA, Moncalvo J-M, Vilgalys R, Redhead S. (2006). "Delineating the Hygrophoraceae: character myths vs. gene trees (poster)" (PDF). Inoculum 57 (4): 27.
- Rotheroe M, Newton A, Evans S, Feehan J. (1996). "Waxcap-grassland survey". The Mycologist 10: 23–25. doi:10.1016/s0269-915x(96)80046-2.
- Seitzman BH, Ouimette A, Mixon RL, Hobbie EA, Hibbett DS. (2011). "Conservation of biotrophy in Hygrophoraceae inferred from combined stable isotope and phylogenetic analyses". Mycologia 103 (2): 280–290. doi:10.3852/10-195.
- Kirk PM, Cannon PF, Minter DW, Stalpers JA. (2008). Dictionary of the Fungi (10th ed.). Wallingford, UK: CABI. p. 446. ISBN 978-0-85199-826-8.
- Griffith GW, Easton GL, Jones AW. (2002). "Ecology and diversity of waxcap (Hygrocybe spp) fungi". Botanical Journal of Scotland 54: 7–22. doi:10.1080/03746600208685025.
- Boa ER. (2004). Wild edible fungi: a global overview of their use and importance to people. Food and Agriculture Organization of the United Nations. p. 147. ISBN 92-5-105157-7.
- Candusso M. (1997). Fungi Europaei 6: Hygrophorus s.l.. Alassio, Italy: Libreria Basso. p. 784.
- Bon M. (1990). Flore mycologique d'Europe 1: Les Hygrophores (in French). Amiens Cedex: CRDP de Picardie. p. 99.
- Arnolds E. (1990). Genus Hygrocybe in Flora Agaricina Neerlandica 2. Lisse, Netherlands: AA Balkema. pp. 71–111. ISBN 90-6191-971-1.
- Largent DL. (1985). The Agaricales (Gilled Fungi) of California 5: Hygrophoraceae. Eureka, California: Mad River Press. p. 220. ISBN 0-916422-54-2.
- Young AM. (2005). Fungi of Australia: Hygrophoraceae. Collingwood, Victoria: CSIRO Publishing. p. 188. ISBN 978-0-643-09195-5.
- Horak E. (1990). "Monograph of the New Zealand Hygrophoraceae (Agaricales)". New Zealand Journal of Botany 28: 255–309. doi:10.1080/0028825x.1990.10412313.