A new pelagic Polyconchoecia Xiang, Chen and Du, 2018 (Ostracoda: Myodocopa: Halocyprididae) fromthe South China Sea

Halocyprid ostracods are appreciable part of ostracods floating through virtually everywhere in marine environment. In this study, we describe a new species of genus Polyconchoecia Xiang, Chen and Du, 2018, tribe Conchoeciini Chavtur and Angel, 2011, family Halocyprididae Dana, 1853 from the middle of the South China Sea. Polyconchoecia chenii sp. nov. is very close to P. commixtus Xiang, Chen and Du, 2018. But it differs from P. commixtus by the distinctions of locations of major glands of carapace and the characteristics of appendages:more posteriorly situated left asymmetric gland of carapace, no right asymmetric gland; segmented frontal organ;the endopod 2 of the first antenna with a very small seta; a- and c-setae of the first antenna with long end joint have long end joint, the b- and d-setae have no end joint, spinose e-seta without end joint; the e-seta of the second antenna is present; teeth side is distinctive; the setal counts of the mandible, maxilla, fifth limb, and sixth limb are individual. The locations of the major glands on carapace and the characteristics of the first antenna can be the key of the new species. This work is the second discovery of the genus Polyconchoecia from the world.