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


L. Watson and M. J. Dallwitz


Morphology. Snails, with a conspicuous, spiral, univalve shell.

The animal with one pair of tentacles only. Eyes at the bases of the tentacles (slightly behind them).

The shell inoperculate; rising-spiral; 4.5–5 whorled (Carychium), or 5–7 whorled (Ovatella and Leucophytia); typically dextral; higher than wide; 1.6–2.5 mm high (Carychium), or 5–8 mm high (Leucophytia, Ovatella); 0.8–0.9 mm wide (Carychium), or 2.5–3.8 mm wide (approximately, in Leucophytia and Ovatella); height about 1.8–2.1 x the width; high-spired and tapered gradually from the body whorl. The height of the spire about 0.3–0.47 x that of the shell. The spire acute to obtuse. The shell tear-shaped (in Ovatella and Leucophytia), or ovoid-symmetric (Carychium); shallowly sutured to deeply sutured (more deeply so in Carychium). The body whorl moderately convex. The whorls of the spire feebly convex to very strongly convex. The whorls neither shouldered nor keeled. The aperture lunate (or auriculate); bearing teeth. The columella folded, or twisted. The shell without an umbilicus. The shell thick-lipped; thin and translucent (Carychium), or opaque (Ovatella and Leucophytia); colourless and semi-transparent when fresh in Carychium, and white, brown or yellowish in Leucophytia and Ovatella; plain.

General biology, ecology. Terrestrial, or terrestrial to freshwater aquatic (Carychium minimum being more or less amphibious, common in moist places under rotting logs or in leaf litter), or semi-marine (Ovatella and Leucophytia, living around high tide mark, but terrestrial rather than aquatic). Breathing air directly via the lung-like mantle cavity.

Hermaphrodite (but individuals acting as either male or female when mating).

Classification. Gastropoda; Pulmonata.

British representation. Carychium (2, “Herald snails, Sedge snail”), Leucophytia (1), Ovatella (1, “Mouse-eared snail”).

Illustrations. • Carychium minimum, Leucophytia bidentata, Ovatella myosotis (Reeve). • Carychium minimum, with Aciculidae, Clausiliidae, Cochlicopidae, Ferussaciidae (Adams).

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.’.