MolluscIreland - land and freshwater
  • Sphaerium nucleus (S. Studer, 1820)
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Sphaerium nucleus
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
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Very similar to the widespread Sphaerium corneum but with a shell which is more distinctly inflated, and possessing dense accumulations of glassy pores around the umbo. Probably widespread but much under-recorded and so far known mainly from shallow, calcareous and sometimes temporary water bodies in Ireland.

Key characteristics

  • A small, very broadly oval and very tumid bivalve
  • Surface silky with fine, concentric growth ridges
  • Coloured shades of brown to greyish
  • Umbos rounded, more or less central
  • With high concentrations of very fine glassy pores near the umbos (!microscope, x40)


9-11 mm.

Irish Distribution

With only a few confirmed records in Ireland. Locally common in turloughs in Clare/south-west Galway (Williams et al., 2010)


  • Little known but suggesting a preference for base-rich lentic water bodies
  • Prefers shallow but richly vegetated places, sometimes temporary habitats
  • Often found with a rich molluscan fauna


Not recognised in the British Isles before about 2001 so little known to British and Irish conchologists.

Red List status

  • Vulnerable (VU).

Wikipedia link

Wikipedia page for Sphaerium nucleus

 Anderson, R., (2016). Sphaerium nucleus (S. Studer, 1820). [In] MolluscIreland. Accessed on 2024-03-02.