| | The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels) |
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.
Hermaphrodite.
Classification. Gastropoda; Pulmonata.
Representation in Britain and Ireland. 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). LIMACIDAE. Limax maximus Linn., "Great Grey Slug". Animals 100–160(-200) mm long when extended. From Taylor (1903). • Limax cinereoniger: typical form and varieties (Taylor). LIMACIDAE. Limax cinereoniger Wolf, "Ash-black Slug". Animals 100–200 mm long when extended. From Taylor (1903). • Lehmannia marginata, Limax flavus, Macrolimax tenellus, Tandonia sowerbyi: typical forms and varieties (Taylor). LIMACIDAE. 1–4, Macrolimax tenellus (Müller), "Slender Slug" or "Tender Slug", animals 35–50 mm long when extended. 5–9, Limax flavus Linn., "Yellow Slug", animals 80–130 mm. 10–17, Lehmannia marginata (Müller), "Tree Slug", animals 70–80 mm. From Taylor (1905). • Lehmannia marginata, Limax flavus, L. maximus, L. cinereoniger, Macrolimax tenellus (Ellis). LIMACIDAE. 1, Limax maximus; 2, Limax cinereoniger Wolf, "Ash-black Slug", 100–200 mm.; 3, Limax flavus L., "Yellow Slug", 80–130 mm.; 4, Lehmannia marginata (Müller), "Tree Slug", 70–80 mm.; 5, Malacolimax tenellus (Müller), "Slender Slug" or "Tender Slug", 35–50 mm. AGRIOLIMACIDAE: 6, Deroceras reticulatum (Müller), 35–45 mm.; 7, Deroceras laeve (Müller), "Marsh Slug", 15–25 mm. From Ellis (1926). • Lehmannia marginata, Limax flavus and Limax maximus, with other slug families (Adams). ARIONIDAE. 1, Arion ater (Linn.), "Large Black Slug"; 2, Arion intermedius Normand, "Hedgehog Slug"; 3, Arion hortensis agg., "Garden Slug"; 5, Geomaculus maculosus Allman, "Kerry Slug". LIMACIDAE. 6, Limax maximus Linn., "Great Grey Slug"; 7, Limax flavus Linn., "Yellow Slug"; 8, Lehmannia marginata (Müller), "Tree Slug". AGRIOLIMACIDAE: 4, Deroceras laeve (Müller), "Marsh Slug"; 9, Deroceras reticulatum (Müller), "Field or Milky Slug". MILACIDAE: 10, probably Tandonia sowerbyi (Férussac), "Sowerby's Keeled Slug". From Adams (1896). • Lehmannia marginata, Limax flavus, Limax maximus, Malacolimax tenellus (Reeve). LIMACIDAE. 1, Limax maximus L., "Great Grey Slug". 2, Limax flavus L., "Yellow Slug". 3, Lehmannia marginata (Müller), "Tree Slug". 4, Malacolimax tenellus (Müller), "Tender Slug", "Slender Slug". From Reeve (1863, with approximte 2cm scale added).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, 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. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels). Version: 5th August 2019. delta-intkey.com’.
