Phylum Mollusca Linnaeus, 1758 - molluscs Class Bivalvia Linnaeus, 1758 - bivalves Subclass Protobranchia Pelseneer, 1889 Order Nuculida Dall, 1889 Superfamily Nuculanoidea Adams & Adams, 1858 (1854) Family Yoldiidae Dall, 1908 Subfamily Yoldiellinae Allen & Hannah, 1986 Genus Portlandia Mörch, 1857