A Field Guide to the Snails of Lord Howe Island

149 Oxychilus alliarius Family Oxychilidae Oxychilidae is a family of 23 genera distributed in North America and Europe, and including several species that are widely introduced. Oxychilids include snails and semislugs with thin, glossy shells and a long, narrow foot. The family Oxychilidae was previously included within Zonitidae but is currently considered to belong to a separate superfamily, the Gastrodontoidea, along with Gastrodontidae. Oxychilus alliarius (Miller, 1822) Garlic Snail Shell. Size: H = 2.4-3.1 mm, D = 5-6.3 mm. Colour: Golden brown. Shape: Discoidal with a low spire; sutures weakly impressed. Sculpture: Shell glossy, shining, smooth. Aperture: Lunately ovate. Umbilicus: Moderately widely open. Animal. Body blackish blue. Key distinguishing features. Glossy shell, moderately widely open umbilicus, weakly impressed sutures; emits a strong smell of garlic when disturbed. Habitat and occurrence. First recorded in 1999 and known from relatively few sites in the North Bay, Settlement and Intermediate Hill areas. Native to Western and Central Europe. Remarks. Oxychilus alliarius is carnivorous and preys on small snails. It is thought to have had a significant impact on native snail populations where it has been introduced, so should be considered a serious potential threat. 5 mm