MolluscIreland - land and freshwater
  • Pisidium moitessierianum Paladilhe 1866 Pygmy pea mussel

Map hosted by the National Biodiversity Data Centre, Waterford
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A very small, long-oval, obliquely wedge-shaped shell with prominent umbos slightly behind the mid point. Umbos demarcated by a shallow furrow. Surface silky, with regular concentric striae. Rare, in central canals.

Key characteristics

  • A very small, long-oval shell with a characteristic wedge-shaped appearance
  • Umbos prominent and slightly behind the mid point; demarcated by a shallow furrow
  • Surface dull or silky, with regular concentric striae
  • Colour grey or cream



World Distribution

Found mostly in southern half of Europe and extending as far east as western Siberia. Distribution type: Eurosiberian Southern-temperate (84).

GBIF distribution map [open in new tab]

Irish Distribution

Rare in Ireland. There is an old record for the Lagan Canal at Moira (Stelfox, 1919), a site which Kerney (1969) visited but in which he failed to re-find the species. He was of the opinion that the habitat had become unsuitable in the half century which had elapsed since the original record. It is also known from Dublin, Galway, Roscommon, Kilkenny and Tipperary. Thought to be extinct at one time but re-discovered along the Royal and Grand Canals by Moorkens & Killeen (2005) and probably also still in the Suir/Nore catchment.


  • Characteristic of slow-flowing, moderately calcareous rivers
  • Probably not very tolerant of enrichment

Red List status

  • Endangered (EN).

Wikipedia link

Wikipedia page for Pisidium moitessierianum

 Anderson, R., (2016). Pisidium moitessierianum Paladilhe 1866. [In] MolluscIreland. Accessed on 2024-03-02.