Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Prosobranchia Milne-Edwards, 1848 - prosobranchs see Class Gastropoda Cuvier, 1795
       Order Caenogastropoda Cox, 1960 see Superorder Caenogastropoda Cox, 1960
         Superfamily Rissooidea Gray, 1847
           Family Hydrobiidae Stimpson, 1865
             Subfamily Nymphophilinae Taylor, 1966
               Genus Pyrgulopsis Call & Pilsbry, 1886