The families of British non-marine molluscs (slugs, snails and mussels)


L. Watson and M. J. Dallwitz


Morphology. Slugs, with no external shell.

35–200 mm long when fully extended. With a small, totally internal, asymmetrical shell. Contracting protectively when molested, but not assuming the hemispherical or sub-globular form characteristic of Arionidae. The body variable in colour: cream, ashy-black to grey or greenish-grey, yellow or pale brown, sometimes mottled or longitudinally dark-banded or striped. The mucous colourless, or milky, or colourless from the foot, and yellow or orange from the body (e.g., in Limax flavus and L. tenellus). The mantle anterior and large; with a fingerprint-like pattern of fine, concentric rings; with the concentric rings centred on its mid-line. The animal with two pairs of tentacles (the anterior pair short). Eyes at the tips of the posterior tentacles. The jaw arcuate, with a vertical central keel ending in a median projection on the lower edge (cf. Zonitidae). The respiratory pore towards the posterior right of the mantle. The tail dorsally bluntly keeled, but the keel falling short of the mantle.

General biology, ecology. Terrestrial. Mainly naturally woodland ground dwellers or climbers, or especially in places associated with human activities (gardens, rubbish tips, roadsides, ploughed fields, etc.), in moist ground litter and herbage; nocturnal, hiding by day under logs, stones, bark, etc. Seemingly feeding mostly on algae, fungi and deacaying vegetable mater, rather than on living plants.


Classification. Gastropoda; Pulmonata.

British representation. Lehmannia (2, “Tree slug, Greenhouse slug”), Limax (4, “Great Grey, Ash-black, and Yellow slugs”), Malacolimax (1, “Slender slug”).

Illustrations. • Limax maximus: typical form and varieties (Taylor). • Limax cinereoniger: typical form and varieties (Taylor). • Lehmannia marginata, Limax flavus, Macrolimax tenellus, Tandonia sowerbyi: typical forms and varieties (Taylor). • Lehmannia marginata, Limax flavus, L. maximus, L. cinereoniger, Macrolimax tenellus (Ellis). • Lehmannia marginata, Limax flavus and Limax maximus, with other slug families (Adams). • Lehmannia marginata, Limax flavus, Limax maximus, Malacolimax tenellus (Reeve).

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of British non-marine molluscs (slugs, snails and mussels). Version: 4th January 2012.’.