Description: A more oval shell than A. cygnea, with umbos nearly central. Periostracum glossy, more often green than brown. The shell is thicker in front than behind and becomes thicker still towards the lower margin. The shell of A. cygnea is of a fairly even thickness throughout. Mainly found where bottom sediments are coarse. 70 -130 mm.

World Distribution: Extends across central Europe south to the Mediterranean countries and east to Siberia. Range Eurosiberian Southern-temperate (84).

Irish Distribution: Overlooked in Ireland for many years but now recognized as widespread in most lowland counties, except in the extreme west and north. It was discovered comparatively late in Lough Erne (Anderson, 1983) and Lough Neagh (Anderson, 1992c).

Ecology:

• Ellis (1969) indicates that it has a preference for flowing water and sandy bottoms in Britain
• In Ireland, both sandy and muddy bottoms may be occupied and large mixed aggregations with A. cygnea have been encountered in Upper Lough Erne and other places
• In general, associated more with moving water and sandy bottoms

Key Identification Features:

• A very large oval, relatively thin, shell
• Umbos nearly central
• Periostarcum glossy and usually with green tints
• Irish populations of this species are notoriously variable and individual animals may be difficult to name with certainty, especially when they occur mixed with A. cygnea which happens not infrequently
• Shell thicker in front than behind and becomes thicker still towards the lower margin - can be seen by holding shells in front of a strong light source

Red list status:

• Vulnerable (VU).

Distribution Map from NBN: Anodonta anatina at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Anodonta anatina at iNaturalist World Species Observations database.

GBIF data for Anodonta anatina | Classification: Bivalvia, Unionida, Unionidae, Anodonta

Thumbnails for genus Anodonta