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• Vallonia cf. excentrica Sterki 1893 Excentric grass snail

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© Dr Roy Anderson

Shell flattened-depressed, whitish translucent, smooth and only irregularly striate, mainly at the umbilicus. Aperture oblique and inclined downwards. Lip expanded smoothly outwards but without a noticeable rim outside. Widespread in dry grassland.

Key characteristics

• A very small, flattened, ivory-white shell
• Sculpture consists of irregular striations which are visible mainly around the umbilicus
• Aperture oblique and inclined downwards
• Lip expanded smoothly outwards but without a distinct rim
• Last whorl expands rapidly giving the umbilicus an excentric appearance

Size

2-2.3 mm.

World Distribution

Found across the temperate northern hemisphere. Distribution type: Circumpolar Wide-temperate (66).

GBIF distribution map [open in new tab]

Irish Distribution

With a similar distribution and constraints as V. costata but more widespread in northern areas and less strongly thermophilic.

Ecology

• Locally common on limestone or other basic grassland
• Also in dry places along the coast, gradually decreasing northwards

Taxonomy

The phylogenetic analysis of Korte & Armbruster (2003) indicates that V. excentrica comprises two paraphyletic taxa which are difficult or impossible to distinguish on shell morphology. As it is impossible to identify which of the taxa occurs Ireland, the excentrica complex is given here as Vallonia cf. excentrica pending further investigations.

Red List status

• Least concern (lc).

Wikipedia link

Wikipedia page for Vallonia excentrica