MolluscIreland - land and freshwater
  • Pisidium conventus Clessin 1877 Arctic-alpine pea mussel

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A thin, fragile shell with broad and flattened with umbos near the mid point. Surface silky with fine, concentric striation. Very rare as a relic of colder climatic periods in deep, cold, upland lakes.

Key characteristics

  • A small, thin, laterally compressed shell
  • Almost oval in shape
  • With flattened umbos near the mid-point
  • Colour yellowish-white
  • Periostracum slightly silky/glossy

Size

2.2-2.8 mm.

World Distribution

Widely distributed in the far north of both the Palaearctic and Nearctic regions. Distribution type: Circumpolar Boreo-arctic montane (26).

Irish Distribution

Recorded only from Brandon Mountain, Kerry, Lough Barra in Donegal and Lough Aquire in Fermanagh. The only recent record is for a loughan on Brandon Mountain (Moorkens, 2005).

Ecology

  • Confined to cold mountain lakes above 300m asl
  • Lives in fine muddy sediments with Littorella on the margins of a loughan on Mount Brandon

Red List status

  • Critically endangered (CR).

Wikipedia link

Wikipedia page for Pisidium conventus

 Anderson, R., (2016). Pisidium conventus Clessin 1877. [In] MolluscIreland.
http://www.habitas.org.uk/molluscireland/species.asp?ID=80 Accessed on 2017-10-18.