Protobranchia

Not to be confused with Prosobranchia.

Protobranchia
Two views of a left valve of Acila cobboldiae from the early Pleistocene of the Netherlands
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Subclass:	Protobranchia Pelseneer, 1889
Orders
Nuculanida Nuculida Solemyida
Synonyms
Palaeotaxodonta

Protobranchia is a subclass of bivalve molluscs.[1] 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.[2]

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.[3]

Subclass: Protobranchia

Order: Nuculanida[4]

• Superfamily: Nuculanoidea
  • Family: Bathyspinulidae
  • Family: Lametilidae accepted as Phaseolidae
  • Family: Malletiidae
  • Family: Neilonellidae
  • Family: Nuculanidae
  • Family: Siliculidae
  • Family: Tindariidae
  • Family: Yoldiidae

Order: Nuculida[5]

• Superfamily: Nuculoidea
  • Family: Nuculidae
  • Family: Sareptidae

Order: Solemyida[6]

• 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

References

1. Protobranchia Pelseneer, 1889. Retrieved through: World Register of Marine Species on 8 July 2010.
2. Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 340. ISBN 0-03-056747-5.
3. Bieler, R., Carter, J.G. & Coan, E.V. (2010) Classification of Bivalve families. Pp. 113-133, in: Bouchet, P. & Rocroi, J.P. (2010), Nomenclator of Bivalve Families. Malacologia 52(2): 1-184
4. Nuclanoida Carter, D.C. Campbell & M.R. Campbell, 2000. Retrieved through: World Register of Marine Species on 9 October 2010.
5. Nuculida Dall, 1889. Retrieved through: World Register of Marine Species on 20 September 2010.
6. Solemyoida Dall, 1889. Retrieved through: World Register of Marine Species on 9 July 2010.