Arion distinctus Mabille, 1868 Darkface Arion
Arionidae, Stylommatophora, Gastropoda, Mollusca, Animalia
Dorsal surface varies from dark brown to black; mantle bands black, close to mantle edges; slender, 30 to 40 mm long; native to northwestern Europe; very common in gardens and fields in lowlands in western Washington; herbivorous; eggs transparent, becoming yellow opaque, up to three dozen per cluster, 2.5 x 2 mm. The similar looking Arion hortensis Férussac, 1819 has also been introduced to North America and is separable from A. distinctus only by dissection or molecular analysis. Dissection has not confirmed the presence of A. hortensis in the Pacific Northwest.