A new genus of large Vesicomyidae (Mollusca, Bivalvia, Vesicomyidae, Pliocardiinae) from the Congo margin, with the first record of the subfamily Pliocardiinae in the Bay of Biscay (northeastern Atlantic)

A new genus in the subfamily Pliocardiinae (Vesicomyidae), Christineconcha n. gen., is established for “Calyptogena” regab Cosel & Olu, 2009. The most characteristic features of Christineconcha n. gen. are a rather thin and elongate shell up to 122 mm in length, a pallial line starting from the ventral margin of the anterior adductor scar, the presence of the inner demibranch only and the absence of the pallial fusion between the pedal gape and the inhalent siphon. Morphologically, Christineconcha is closest to the genus Abyssogena Krylova & Sahling, 2010. The monospecific new genus occurs in the Atlantic on the continental margin of Africa and Europe, from the Gulf of Guinea to the southern Bay of Biscay, at depths of 2820-4017 m. In the Gulf of Guinea, Christineconcha n. gen. is recorded from cold seeps; in the Bay of Biscay, the record of C. regab n. comb. indicates the likely presence of reducing biotopes. Morphological basis for the slightly different ecological niches of the co-occurring species Christineconcha regab n. comb. and Laubiericoncha chuni (Thiele & Jaeckel, 1931) is discussed.