Deroceras

Deroceras is a taxonomic genus of small to medium sized air-breathing land slugs in the family Agriolimacidae. Most species reach only 30–35 mm in length (max 45 mm). Coloration varies considerably within and between species but common patterns are pale cream, with or without darker flecks (never stripes), and a more uniform light gray or brown to black-brown. Mucus is usually colourless but in some species includes a white deposit when the slug has been disturbed. No keel continues from the tail along the back. The mantle is large (up to half the body length), containing a shell plate internally. The pneumostome lies in the posterior half of the mantle. Generally external appearance does not reliably distinguish one species from certain others, so species identification requires dissection to reveal the genitalia, unless the local species diversity is known to be low. The taxonomy, anatomy and other aspects of the biology of this genus were reviewed in 2000, and the diverse mating behaviors were reviewed in 2007. In 2000, in the most recent monograph on the genus, Wiktor rejected earlier attempts (including his own) at a subgeneric (Agriolimax Mörch, 1865, Plathystimulus Wiktor, 1973) classification, because there appeared to be so many convergences and reversals. The only exception was that he split off Liolytopelte as a subgenus because of its distinctive hard plate within the penis; all other species were included in the subgenus Deroceras. There are at least 123 species in the genus Deroceras. Subgenus Deroceras Rafinesque, 1820 Subgenus Liolytopelte Simroth, 1901 Several species in this genus are recognised as pests of agriculture and horticulture, including Deroceras reticulatum, Deroceras invadens, Deroceras agreste, and Deroceras laeve.