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

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L. Watson and M. J. Dallwitz

Milacidae

Morphology. Slugs, with no external shell.

45–75 mm long when fully extended. With a small, totally internal, symmetrical shell. Not slender and worm-like when extended. Contracting protectively when molested, but not assuming the hemispherical or sub-globular form characteristic of Arionidae. The body variable in colour: black, brown or dark-, brownish- or yellowish-grey, sometimes speckled or reticulated with black. The mucous colourless, or milky. The mantle anterior and large; shagreened, and exhibiting a large dorsal island, demarcated by a conspicuous groove. The animal with two pairs of tentacles (the anterior pair short). Eyes at the tips of the posterior tentacles. The jaw not as in Zonitidae and Limacidae (?). The respiratory pore towards the posterior right of the mantle. The tail dorsally sharply keeled, the keel reaching to the mantle.

General biology, ecology. Terrestrial. Lifestyle rather subterranean (T. sowerbyi), or not subterranean. In woods and hedges, gardens and fields, M. gagates, T. budapestensis and T. sowerbyi being notable pests. Herbivorous.

Hermaphrodite.

Classification. Gastropoda; Pulmonata.

British representation. Milax (1, “Jet slug”), Tandonia (3, “Keeled slug, Budapest slug”).

Illustrations. • Milax gagates and Tandonia sowerbyi: assorted varieties (Taylor). • Milax gagates and Tandonia sowerbyi, with other slugs (Ellis). • Milax gagates and Tandonia sowerbyi (Reeve). • Tandonia sowerbyi, with Arionidae, Agriolimacidae and Limacidae (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. http://delta-intkey.com’.

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