A Noteworthy New Species of the Family Vesicomyidae from the South China Sea (Bivalvia: Glossoidea)

Abstract

"Calyptogena" marissinica n. sp. is described from the Haima cold seep on the northwestern slope of the South China Sea, China, at depths of 1,372 m and 1,398 m. Phylogenetic reconstruction using the cytochrome oxidase c subunit I (COI) gene shows that it is sister to Calyptogena similaris but distinct from that species by a pairwise distance of 3.9%, larger than the average intraspecific variation within the genus Calyptogena sensu lato. Morphologically, the new species is distinguished from C. similaris in having a less elongate shell, with nearly straight ventral margin, and no apparent anterior lateral tooth.