MolluscIreland - land and freshwater
  • Arion (Carinarion) circumscriptus Johnston 1828 Forest slug
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Arion (Carinarion) circumscriptus
© Dr Roy Anderson
Arion (Carinarion) circumscriptus
© Dr Roy Anderson
Arion (Carinarion) circumscriptus
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
To view the species profile on Biodiversity Maps and access the live map, please click on the map.


A 'keeled' roundback slug, grey or brown on the back with darker spots, thin lateral bands, grey sides below the bands and white sole. The 'keel' consists of a line of tubercles on the back i.e. not a real keel. Widespread in woodland.

Key characteristics

  • A roundback slug with grey back flecked with darker grey, thin lateral bands, and grey sides with white sole
  • The 'keel' consists of pale, raised tubercles along the back; these are evident in both adults and young, but more conspicuous in the young
  • Mucus sticky, clinging, colourless to yellowish
  • Contracts to a bell shape


30-38 mm.

World Distribution

Mainly middle and northern latitudes in Europe. Distribution type: European Temperate (73).

GBIF distribution map [open in new tab]

Irish Distribution

Widespread and locally common.


  • A characteristic species of leaf litter and dead wood in woodlands
  • Can occur in open woodland with Arion silvaticus
  • Also found occasionally in gardens but not on agricultural land
  • More localised and less common towards the west

Red List status

  • Least concern (lc).

Wikipedia link

Wikipedia page for Arion circumscriptus

 Anderson, R., (2016). Arion (Carinarion) circumscriptus Johnston 1828. [In] MolluscIreland. Accessed on 2024-03-02.