MolluscIreland - land and freshwater
  • Vertigo (Vertilla) angustior Jeffreys 1830 Narrow-mouthed Whorl Snail
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Vertigo (Vertilla) angustior
© Dr Roy Anderson
Vertigo (Vertilla) angustior
© Dr Roy Anderson

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A very small sinistral shell. Smaller than V. pusilla, the other sinistral Vertigo. Shell slightly darker, mid-brown, with a more obvious fine, regular radial sculpture. Aperture with 5-6 mainly short denticles: 2 parietal; 2 columellar; 1 palatal, the latter relatively long. Very local.

Key characteristics

  • A very small, sinistral mid-brown shell
  • Faintly glossy with fine, regular, radial sculpture
  • Aperture triangular with 5-6 mainly short denticles: 2 parietal; 2 columellar; 1 palatal
  • Lip thin, barely reflected, with a strong sinuosity or indent

Size

1.6-1.8 mm.

World Distribution

Found across central and northern Europe east to the Caucasus. Distribution type: European Temperate (73).

Irish Distribution

Local and rare in Ireland and the British Isles as a whole although once widespread. A Boreal relict and now restricted to dune slacks and marshes in the west and north and to a few rich marshes across the central plain. In northern Ireland it is known from dune grassland at Ballycramsy near Malin Head (Anderson 1981), Streedagh Estuary, Donegal Bay (pers. comm. of G. A. Holyoak) and along the Giantís Causeway in north Antrim (Stelfox, 1907; Holyoak, 2005). Abundant as a subfossil in dune pockets along the north coasts of Antrim and Londonderry (Standen, 1897; Welch, 1898).

Ecology

  • This species was common before the wide-scale Postglacial investment of landscapes by forest - like other Boreal relicts such as Succinella oblonga, it has survived only where suitable open habitats have survived the millennia
  • Unlike Vertigo geyeri, with a similar history, angustior has never tenanted upland or overly exposed places and sites tend to be low altitude, moderately to heavily grazed with a sparse, low vegetation, and to be calcareous and permanently moist
  • The cessation of grazing on National Trust lands around the Giantís Causeway, however, appears to have had little adverse effect and the species is still abundant in tussocky grassland near the shore

Red List status

  • Vulnerable (VU).

Wikipedia link

Wikipedia page for Vertigo angustior

 Anderson, R., (2016). Vertigo (Vertilla) angustior Jeffreys 1830. [In] MolluscIreland.
http://www.habitas.org.uk/molluscireland/species.asp?ID=188 Accessed on 2017-10-19.