Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848
       Order Cephalaspidea Fischer, 1883
         Superfamily Bulloidea Gray, 1827
           Family Retusidae Thiele, 1925
             Genus Retusa Brown, 1827
               1 Subgenus Retusa Brown, 1827
               2 Subgenus Coleophysis Fischer, 1883
               3 Subgenus Decorifer Iredale, 1937
               4 Subgenus Semiretusa Thiele, 1925