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 Nephronaias Crosse & Fischer, 1894
                 1 Subgenus Elliptoideus Frierson, 1927
                 2 Subgenus Martensnaias Frierson, 1927
                 3 Subgenus Nephritica Frierson, 1927
                 4 Subgenus Reticulatus Frierson, 1927
                 5 Subgenus Sphenonaias Crosse & Fischer, 1894