Class [Mammalia] Linnaeus, 1758 - mammals
   Order Rodentia Bowdich, 1821 - rodents
     Family Muridae Batsch, 1788 - rats, mice, hamsters, voles, lemmings, and gerbils
       Subfamily Arvicolinae Gray, 1821 - voles
         Genus Arvicola Lacépède, 1799 - water voles
           1 Arvicola sapidus Miller, 1908 - southwestern water vole
           2 Arvicola terrestris (C. Linnaeus, 1758) - European water vole