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• Clausilia (Clausilia) bidentata (Ström 1765) Common door snail

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© Dr Roy Anderson

© Dr Roy Anderson

A dark brown, rather slender fusiform shell with dense surface sculpturation and only a weakly glossy to dull surface. Aperture pear-shaped, with strong parietal and weak columellar lamellae. Colour typically dark brown to reddish-brown but often bleached grey with algal stains. Finely and regularly ribbed with delicate, cross-cutting, spiral striation. Generally abundant but mainly in woodland.

Key characteristics

• A slender fusiform shell, not evenly narrowed but of more even width near the apex and blunt-topped
• Surface a rich dark brown, slightly glossy, with dense spiral sculpturation crossed by radial striae
• Aperture roughly pear-shaped with strong parietal lamellae and weak columellar lamellae
• Very variable in size with populations of miniature forms, little over half the height of normal shells, occurring here and there e.g. basalt rocks and dunes on the north coasts of Cos Antrim and Londonderry

Size

7-12 mm.

World Distribution

Ranging from France and the British Isles through Switzerland and the low countries to Denmark, Germany and southern Scandinavia. Distribution type: Suboceanic Temperate (72).

GBIF distribution map [open in new tab]

Irish Distribution

Ubiquitous except on peaty soils or in wetlands.

Ecology

• Abundant throughout on tree boles and fallen timber in broadleaf woodland
• Also common on rocks, screes and lime-mortared walls
• Often in gardens

Red List status

• Least concern (lc).

Wikipedia link

Wikipedia page for Clausilia bidentata