Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Bivalvia Linnaeus, 1758 - bivalves
     Subclass Palaeoheterodonta Newell, 1965 see Clade Palaeoheterodonta Newell, 1965
       Order Unionida Gray, 1854
         Superfamily Unionoidea Rafinesque, 1820
           Family Unionidae Rafinesque, 1820 - pearly mussels
             Subfamily Ambleminae Rafinesque, 1820
               Tribe Amblemini Rafinesque, 1820
                 Genus Parreysia Conrad, 1853
                   1 Subgenus Nyassunio Haas, 1936
                   2 Subgenus Radiatula Simpson, 1900