The two UK species in this genus cannot be clearly separated on visual characters. Ambigolimax valentianus is the commoner, and probably most of the images below are of this species, but without dissection this cannot be proven. A. valentianus (Greenhouse Slug) is generally paler with less prominent dark 'tramlines' but there is overlap with A. nyctelius (Balkan Three-band Slug).

Both species are 55-80mm extended and are pale brown with 2-3 dark lines on the mantle which extend as tramlines along the body. Mature specimens have a translucent, watery appearance. Both have a small keel at the tip of the body and the sole is pale and the mucus colourless.

Unless the species has been confirmed by dissection then please record as Ambigolimax.

Often found near greenhouses, plant nurseries, allotments, under dead wood and in compost bins.

Peak time is summer.

Widespread in England, fewer records from elsewhere in Britain.

Very common in Leicestershire and Rutland.