Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Prosobranchia Milne-Edwards, 1848 - prosobranchs see Class Gastropoda Cuvier, 1795
       Superorder Archaeogastropoda Thiele, 1925
         Order Vetigastropoda Salvini-Plawen, 1980 - archaeogastropods s.l.
           Suborder Neritopsina Cox, 1960 see Order Neritopsina Cox & Knight, 1960
             Superfamily Neritoidea Rafinesque, 1815
               Family Phenacolepadidae Pilsbry, 1895 [monotypic]
                 Genus Plesiothyreus Cossmann, 1888
                   Subgenus Phenocolepas Millard, 1996, orth. inval. see Subgenus Phenacolepas Pilsbry, 1891