- Source: Protobranchia
Protobranchia is a subclass of bivalve molluscs. It contains the extant orders Nuculanida, Nuculida, and Solemyida.
These are deep water clams of a small and primitive order with a taxodont hinge (composed of many similar, small teeth), generally with a central ligament pit, large labial palps which are used in deposit feeding and the gills used only for respiration, the anterior and posterior adductor muscles are nearly equal in size, a foot which is divided sagittally and longitudinally with papillate margins. The foot in Protobranchia clams is without a true byssus gland, although they frequently have a nonhomologous byssal gland in the heel. The byssal gland in these clams does not produce threads as in Pteriomorphia.
2010 Taxonomy
In 2010 a new proposed classification system for the Bivalvia was published in by Bieler, Carter & Coan revising the classification of the Bivalvia, including the subclass Protobranchia.
Subclass: Protobranchia
= Order: Nuculanida
=Superfamily: Nuculanoidea
Family: Bathyspinulidae
Family: Lametilidae accepted as Phaseolidae
Family: Malletiidae
Family: Neilonellidae
Family: Nuculanidae
Family: Siliculidae
Family: Tindariidae
Family: Yoldiidae
= Order: Nuculida
=Superfamily: Nuculoidea
Family: Nuculidae
Family: Sareptidae
= Order: Solemyida
=Superfamily: Manzanelloidea
Family: Manzanellidae
Family: Nucinellidae
Superfamily: Solemyoidea
Family: Solemyidae
= Order: † Praecardiida
=Family: † Butovicellidae
Genus: † Butovicella
Family: † Praecardiidae
Genus: † Slava
Genus: † Cardiola
Family: † Antipleuridae
Genus: † Dualina
Genus: † Hercynella