Arion (Carinarion) circumscriptus Johnston, 1828
Not aggressive (Rollo & Wellington 1979).
Usually secluded in their habitat. Respond strongly to and emerge with rain and moisture gradients, relatively intolerant of dessication and high temperatures (Getz 1959).
Arion fasciatus, A. silvaticus.
External: Dark gray or brown, little speckles of black on mantle, lighter on sides; dark bands on sides of body and mantle; bell-shaped in cross section when contracted; slight keel; white sole; clear mucus (Kerney & Cameron 1979).
Internal: Pigmented epiphallus (Kerney & Cameron 1979); atrium 2x long as wide; spermatheca duct and oviduct equally thick (Wiktor 1983).
Similar to A. fasciatus and A. silvaticus, but darker, and has a much more pigmented epiphallus (Kerney & Cameron 1979). Relative to A. silvaticus, A. circumscriptus has a longer body, spots on mantle, fuzzy lower edge of lateral bands, longer atrium, smaller and pigmented epiphallus (Wiktor 1983).
30-40 mm long (Kerney & Cameron 1979).
Common in NW Europe, to S Scandanavia and E Russia (Kerney & Cameron 1979; Sysoev & Schileyko 2009).
Non-native to: USA and S Canada (Chichester & Getz 1969).
Lowland deciduous forest; valleys, rivers, etc. that provide moist, shady habitat; takes shelter in leaf litter (Wiktor 1996).
In Michigan, adults are present in spring and summer, and they lay eggs in late summer until hibernation. A. circumscriptus may live 2-3 years (Getz 1959).
Feeds on live and decaying plants (Getz 1959).