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• Vertigo (Vertigo) geyeri Lindholm 1925 Whorl Snail

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© Dr Roy Anderson

© Dr Roy Anderson

© Dr Roy Anderson

Shell dextral. Slightly barrel-shaped with strongly tumid whorls. Aperture rounded, with 4 denticles: 1 parietal; 1 columellar; 2 palatal. Shell glossy, nearly smooth (fine growth lines) and pale red-brown but appearing dark because of the very dark animal. Lip with no thickening and lacking a pale callus around the denticles.

Key characteristics

• A tiny dextral, barrel-shaped, red-brown shell
• Aperture rounded, without indent
• Four teeth present: 1 parietal; 1 columellar; 2 palatal
• Lip with no thickening and lacking a pale callus around the denticles
• Shell glossy, appearing smooth, but dark because of the dark animal inside

Size

1.8-2 mm.

World Distribution

Found the Alps, in scattered relict localities across the north European lowlands, and into north and central Scandinavia. Distribution type: Suboceanic Boreal-montane (42).

Irish Distribution

This species is known historically from scattered sites across central and west Ireland (Cos. Offaly, Mayo and Sligo) (Phillips, 1935; Norris & Pickrell, 1972; Cawley, 1996a). In more recent times its range has been extended by field work to Cos Donegal, Leitrim, Fermanagh and Londonderry which suggests a wide distribution in base-rich flushes in the north and west.

Ecology

• The principal habitat appears to be base-rich flushes in ombrogenous bog, with communities isolated from each other by the spontaneous growth of bog following the end of the Boreal period of the Irish Postglacial
• It requires short, mossy vegetation and an alkaline pH to thrive
• Sward height may be critically important

Red List status

• Vulnerable (VU).

Wikipedia link

Wikipedia page for Vertigo geyeri