MolluscIreland - land and freshwater
  • Pisidium lilljeborgii Clessin 1886 Lilljeborg’s pea mussel

Map hosted by the National Biodiversity Data Centre, Waterford
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A fairly tumid, rounded, trapezoidal shell with fairly narrow umbos slightly behind the mid point. Surface fairly glossy, with coarse, irregular concentric striae. Colour grey to brownish white. Widespread in the west.

Key characteristics

  • A moderately tumid shell with a less equilateral shape than P. hibernicum
  • Trapezoidal with umbos slightly behind the mid point
  • Surface glossy with coarse, irregular concentric striae
  • Colour grey to brownish white



World Distribution

A northern and alpine species. Distribution type: Circumpolar Boreal-montane (46).

GBIF distribution map [open in new tab]

Irish Distribution

Largely restricted to western and northern parts and much rarer in lowland habitats than related species. Appears to be declining.


  • The principal habitats of this species are deep, clear lakes in mountain districts
  • It lives in sands or gravels on the margins
  • May also occur locally at low altitudes where larger habitats are available in the west and north.

Red List status

  • Vulnerable (VU).

Wikipedia link

Wikipedia page for Pisidium lilljeborgii

 Anderson, R., (2016). Pisidium lilljeborgii Clessin 1886. [In] MolluscIreland. Accessed on 2024-03-02.