Description: A tightly coiled flat shell of 6-6½ whorls. Whorls are convex and the aperture nearly circular, sometimes with a whitish rib inside (leucostoma). Although flattened on the lower side it does not have a keel. Maximum width of last whorl about 18-20% of shell width. Widespread. 5.5-9 mm.

World Distribution: Widespread in Europe. Distribution type: Eurosiberian Wide-temperate (64).

Irish Distribution: Widespread throughout Ireland, even in coastal habitats in the extreme west and north, but local in most areas because of its predilection for minimally-disturbed temporary habitats.

Ecology:

• A characteristic species of temporary water-bodies in the floodplains of lakes and rivers
• Often found with Aplexa hypnorum

Key Identification Features:

• Shell small and a tight, flat coil of 6-6½ whorls
• Whorls are convex and the aperture nearly circular
• A white rib is sometimes present inside the lip
• Flattened on the lower side but lacking a keel
• Maximum width of last whorl 18-20% of shell width

Taxonomy:

• There are two commonly recognized forms of this species in Europe. The narrow-whorled form A. leucostoma is general throughout Ireland whereas the broad-whorled form A. spirorbis seems to be very local and rare and has not been recorded recently.

Red list status:

• Least concern (lc).

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

iNaturalist: Anisus leucostoma at iNaturalist World Species Observations database.

GBIF data for Anisus leucostoma | Classification: Gastropoda, incertae sedis, Planorbidae, Anisus

Thumbnails for genus Anisus