MolluscIreland - land and freshwater
  • Boettgerilla pallens Simroth 1912 Worm slug
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Boettgerilla pallens
© Dr Roy Anderson
Boettgerilla pallens
© Dr Roy Anderson
Boettgerilla pallens
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
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Boettgerilla pallens
© Dr Roy Anderson

A very slender medium-sized keeled slug, pale grayish-yellow in colour, sometimes with a bluish tinge and with a slightly darker head, back and keel. A soil species from south-east Europe, accidentally introduced to Ireland in the 1970s.

Key characteristics

  • A very slender greyish or bluish-grey keeled slug with slightly darker head and back and translucent sides with yellowish internal organs showing through
  • The keel is full length between the back of the mantle and the tail and is the same colour as the back
  • Rear of the mantle comes to a broad point
  • Mantle with a deep V-shaped groove, but also marked by 'finger-print' concentric grooves
  • Sole pale, mucus colourless


35-55 mm.

World Distribution

Originally south-east European but spread via human activities to most of western Europe within the last century.

GBIF distribution map [open in new tab]

Irish Distribution

Very local but increasingly widespread in disturbed sites. First recorded in Ireland in 1973 from Mount Stewart on the Co. Down coast (Anderson & Norris, 1974). Reported from Britain in the previous year and now very widespread there (Kerney, 1999). It appears to be commoner in the southern counties of Ireland than in the north.


  • This distinctive, worm-like slug is predominantly soil-dwelling
  • Most recorded sites are in rubbishy or waste places but there are records for rough pasture and woodland
  • Usually seen only when deeply embedded stones are turned over

Red List status

  • Not applicable

Wikipedia link

Wikipedia page for Boettgerilla pallens

 Anderson, R., (2016). Boettgerilla pallens Simroth 1912. [In] MolluscIreland. Accessed on 2024-06-24.