Northern Ireland's Priority Species

Porpoloma metapodium – mealy meadowcap

 
Porpoloma metapodium

Porpoloma metapodium (Fr.) Singer
Family: Tricholomataceae

This species is a distinctive fungus found in old unfertilised grasslands. It is large and fleshy but is identified by its thick gills, strong taste and smell of flour, white spore print and by all parts of the fungus blackening with age.

In brief

  • Only found twice in Northern Ireland, one of which was in 1930
  • Found in old semi-natural grasslands, usually upland acidic grassland
  • Fruiting bodies have been recorded from September and October in Northern Ireland, but also in November in Great Britain
  • This is a rare fungus and its presence indicates that the site is likely to be rich in other fungi of conservation concern
  • As well as being rare, it has also declined and Northern Ireland is the Irish stronghold for this species
  • The main threats are from agricultural intensification (especially the application of fertilisers), habitat neglect, reduction of habitat and lack of awareness.

Species description
In the past, this species has been called Hygrocybe metapodia due to its similar appearance to many waxcaps. It has the thick waxy gills of a waxcap, but microscopically, it is quite different. Its white spores are amyloid (stain blue/black in a reagent called Meltzer’s Reagent) compared to the non-amyloid spores of the waxcaps. It is a very robust species with a cap to 15cm wide and a stem up to 10cm tall. It is thick-fleshed and bulky with a smooth brown cap that breaks up with age. Its gills are grey to vinaceous buff and its smell is usually strongly of flour. If bruised when handling or if the fruiting body is cut, it will turn black which is a very distinctive characteristic.

Life cycle
The earliest fruiting body recorded in Northern Ireland was found on 27 September and the latest on 17 October, although its true fruiting period is probably much longer.

Similar species
This is a very distinctive species marked by its robust, bulky stature, its blackening flesh and amyloid spores. This distinguishes it from any Hygrocybe and the only species that it might be confused with belong to the genus Dermoloma. D. magicum also has amyloid spores and blackens. However, it is much smaller in stature and, microscopically, the cells in its cap are ellipsoid rather than filamentous as in P. metapodium. D. josserandii var. phaeopodium has the same colours but does not blacken and also has the ellipsoid cap structure. Due to the size difference, it is only young specimens of P. metapodium that should be checked against these Dermoloma species which have yet to be recorded in Northern Ireland but might be found.

How to see this species
This species was recorded from Montalto Estate in Ballynahinch in 1930. It has not been refound, but it is difficult to interpret where the record originated. It could have been the lawn in front of the main house, but also could have been the fields where the Spa Golf Club is now. The modern record from 2000 was from grassland by Goles Forest in the Sperrins. This habitat is more typical of where it is found in the British Isles although it is also known from estate lawns in Wales. Like most ‘waxcap grassland’ species, it is usually found where the grass sward is short and no fertilisers have been applied. Relevant access permissions should be sought prior to visiting any site.

Current status
This is a widespread but rare species across Northern Ireland and the British Isles although records are more concentrated in upland hill pastures of the north and west.

Why is this species a priority in Northern Ireland?

  • It is rare and declining with Northern Ireland being the Irish stronghold for the species.

It is an excellent indicator of old unfertilised grasslands. This habitat is known from the Northern Ireland Countryside Survey to be 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 if this affects the organism under the ground.

Conservation of this species

Current action

  • 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 and Lowland Dry Acid Grassland.

Proposed objectives/actions

  • Publicise conservation value and management requirements of this species amongst site owners and other 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 [at] nifg.org.uk.

Further information

Links
Northern Ireland Habitat Action Plan Lowland Meadow

Northern Ireland Habitat Action Plan Lowland Dry Acid Grassland

Northern Ireland Fungus Group

Waxcaps and other Grassland Fungi

NBN Gateway

British Mycological Society

Waxcaps

Literature
Watling, R. and Turnbull, E. (1998). British Fungus Flora Vol. 8 Royal Botanic Gardens, Edinburgh.

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

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): 225-242. (download as pdf from RIA website 650kb).

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