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
           1 Family Margaritiferidae Henderson, 1929 (1910), nom. cons. [monotypic] - freshwater pearl mussels
           2 Family Unionidae Rafinesque, 1820 - pearly mussels
           3 Family Hyriidae Swainson, 1840