Class Bivalvia Linnaeus, 1758 - bivalves Subclass Autobranchia Grobben, 1894 Superorder Heteroconchia Gray, 1854 Clade Palaeoheterodonta Newell, 1965 Order Unionida Gray, 1854 Superfamily Etherioidea Deshayes, 1832 Family Mycetopodidae Gray, 1840 Subfamily Monocondylaeinae Modell, 1942