Family: Arionidae
Some smaller Arion species
There are about seven or more common Arionid slugs under 7 cm. extended length, but they are difficult for the beginner to identify from external features. The most common is Arion hortensis, agg.,which is comprised of three distinct species, but for present purposes we will consider them as an aggregate.
Arion hortensis Férrusac 1819
Description: Extended length 2.5.- 3 (rarely 4) cm. Body blue-black above with paler flanks, with the dark lateral bands high up on the flanks, arching over the pneumostome on the mantle, and with an orange tip to tail Sole yellow to orange. All forms have yellow-orange body mucus.
Habitat: Ubiquitous - gardens, woods, agricultural land (a major pest), with a slight preference for calcareous or neutral soils.
Arion subfuscus (Draparnaud 1805)
Description: Medium slug, extended length 5 - 7 cm. Usually dark brown, with a single darker longitudinal line, which passes above and below the respiratory pore, and with small elongate tubercles. Mantle usually slightly paler than rest of body. Sole yellowish, body mucus bright yellow (often orange), sole mucus colourless. This species cannot contract into a hemispherical shape as other Arion spp. Colour is somewhat variable, with reddish and grey variants quite common.
Habitat: Very ubiquitous - woods, pastures, gardens hedges and dunes.
Arion circumscriptus Johnston 1828
Description: Small to medium slug, extended length 3 - 4 cm. Dark grey or occasionally brown, mantle lightly speckled with black, lighter towards the foot fringe, with one,thin dark longitudinal band on each side. Sole whitish, mucus colourless.
Habitat: Ubiquitous.