Northern Ireland's Priority Species

Hygrocybe ovina – the blushing waxcap

 
Hygrocybe ovina

Hygrocybe ovina (Bull.) Kühner
Family: Tricholomatales

This is another distinctive ‘Waxcap’ fungus, typical of old unfertilised grasslands, a habitat that is greatly under threat. Waxcaps have been called the orchids of the fungi world due to their bright colours, but this species is one of the dullest of the group. It is, however, also one of the rarest.

In brief

  • Only two recent records in Northern Ireland – Binevenagh NNR and Altnahinch Burn

  • Found in old semi-natural grasslands of high conservation value

  • Fruiting bodies can be seen from August to October, although it has also been recorded in November in Great Britain

  • It is one of the rarest species of this important group of fungi and is only found on sites of rich fungal diversity

  • The main threats are agricultural intensification (especially the application of fertilisers), habitat neglect, reduction of habitat and lack of awareness.

Species description
The fruiting body can be quite large, up to 9cm wide and 12cm tall and often grows in small groups. The colours of the cap and stem are grey brown to dark grey, becoming blackish when old. The gills are also grey to dark grey but turn distinctly red if bruised, as does the flesh if the fruiting body is cut. The cap is convex, smooth when young but can be distinctly rough and scurfy when old. The stem can be grooved but is usually smooth. It can also have a distinctive nitrous smell if cut. These field characteristics mean that it is possible to identify this species with confidence without microscopic examination. It is thought to be a saprotroph, breaking down dead grass and moss, thus playing an important role in the nutrient cycle.

Life cycle
The earliest fruiting body recorded in Northern Ireland was found on 5 August and the latest on 20 October. Both these records are from the same site (Binevenagh NNR) so it seems that it can produce fruiting bodies at the one site for long periods.

Similar species
There are two other Hygrocybe species with a nitrous smell, H. nitrata and H. ingrata. However, H. nitrata does not redden and is much more slender. H. ingrata does redden, but it has a smooth cap, has more red brown colours on the cap and a paler stem that is usually white at the base. The only other species of Hygrocybe that can be so dark is H. conica, blackening waxcap, which turns from a yellow, red or orange colour to black with age or bruising. This species is often more conical and has a fibrillose stem, not a smooth stem.

How to see this species
This species has only been found in Northern Ireland at Binevenagh NNR, County Londonderry and Altnahinch Burn near Slievenorra in North Antrim. As it has been found over a wide range of dates at Binevenagh NNR, if a wide range of other waxcaps are present on the site, there is a good chance of finding it. These modern sites are both acidic grasslands on basalt so there may be diverse soil types with base rich flushes. The grass sward is usually short, moss rich and poor in nutrients. Fruiting bodies can be seen from August to October. Relevant access permissions should always be sought prior to visiting any sites.

Current status
There are only two recent records in Northern Ireland, from Binevenagh NNR, County Londonderry and Altnahinch Burn near Slievenorra in North Antrim. This is a genuinely rare species across the British Isles although records are well spread and there seems to be no north/south or east/west bias.

Why is this species a priority in Northern Ireland?

  • This species is rare and declining, with Northern Ireland being the Irish stronghold.

It is an excellent indicator of old unfertilised grasslands. Data from the Northern Ireland Countryside Survey would indicate that this habitat is decreasing in extent.

Threats/Causes of decline
The main reasons for decline are agricultural intensification (primarily the application of phosphorus and other nutrients) and habitat loss. Grassland neglect where the sward becomes rank also restricts fruiting, although it is not clear whether this affects the organism under the ground.

Conservation of this species

Current action

  • One of the two sites is covered by several statutory designations – Binevenagh is an ASSI, SACand NNR

  • A grassland fungi survey funded by EHS for the whole of Northern Ireland 2002-04 produced a good overview of the distribution of the species

  • Production of Grassland Fungi conservation leaflet by Fungal Conservation Forum

  • Implementation of the Northern Ireland Habitat Action Plans for Lowland Meadow, Lowland Dry Acid Grassland and Calcareous Grassland.

Proposed objectives/actions

  • Maintain the number of viable populations of this species

  • Publicise conservation value and management requirements of this species amongst managers of existing / potential sites

  • Research into ecological requirements.

What you can do
This is a distinctive species that indicates that any site where it is found will be particularly rich in grassland fungi. Any new records should be reported to the Northern Ireland Fungus Group. Records can be sent in using online recording forms or by contacting david.mitchel@nifg.org.uk.

Further information

Links
Northern Ireland Fungus Group

Information on waxcaps

NBN Gateway

British Mycological Society

British Waxcap website

Northern Ireland Habitat Action Plans

Binevenagh ASSI

Literature
Boertmann, D. (1995). The Genus Hygrocybe. Copenhagen, The Danish Mycological society. This is the best identification guide for the group.

Evans, S. (2004). Waxcap-grasslands – an assessment of English sites. English Nature Research Report No 555

Griffith, G.W., Easton, G.L. and Jones, A.W. (2002). Ecology and Diversity of Waxcap (Hygrocybe spp.) Fungi. Botanical Journal of Scotland 54(1), pp. 7-22. (download)

McHugh, R., Mitchel, D., Wright, M and Anderson, R. (2001). The fungi of Irish grasslands and their value for nature conservation. Proceedings of the Royal Irish Academy 101B (3), pp. 225-242. (download).

Newton, A.C., Davy, L.M., Holden, E., Silverside, A., Watling, R. and Ward, S.D. (2002). Status, distribution and definition of mycologically important grasslands in Scotland. Biological Conservation 111, 11-23.

Text written by:
David Mitchel