MolluscIreland - land and freshwater
  • Anisus (Anisus) leucostoma (Millet 1813) White-lipped ramshorn
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Anisus (Anisus) leucostoma
© Dr Roy Anderson
Anisus (Anisus) leucostoma
© Dr Roy Anderson

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A tightly coiled flat shell of 6-6 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.

Key characteristics

  • Shell small and a tight, flat coil of 6-6 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

Size

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

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).

Wikipedia link

Wikipedia page for Anisus leucostoma

 Anderson, R., (2016). Anisus (Anisus) leucostoma (Millet 1813). [In] MolluscIreland.
http://www.habitas.org.uk/molluscireland/species.asp?ID=9 Accessed on 2017-12-11.