New Cenozoic Deep-Sea Genus, <i>Abyssocythere</i> (Crustacea: Ostracoda: Trachyleberididae), with Descriptions of Five New Species

Abstract

The new genus Abyssocythere Benson has been erected to receive five new species and one described species of psychrospheric ostracode ranging in age from the Paleocene to the Recent. These species include Abyssocythere casca Benson, new species (Indian Ocean), herein designated the type species, A. pannucea Benson, new species (eastern Pacific), A. japonica Benson, new species (western Pacific), A. atlantica Benson, new species (Atlantic), A. australis (Southern Ocean), and A. trinidadensis (van den Bold) from the Caribbean region. Modern species are typical of the deep-sea floor and are common to depths below 2,000 meters. Fossils have been found in deep-water Paleocene and Miocene strata in Trinidad and in deep-sea cores in Pleistocene sediments. These species are thought to have descended from a yet unknown form of the complex of species assigned to the Cretaceous genus Cythereis (sensu lato). There seems to be an evolution of finer surface features of the carapace and an increase in size throughout the Cenozoic.