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 Unioninae Rafinesque, 1820
               Genus Unio Philipsson, 1788
                 1 Subgenus Eolymnium Prashad, 1919