Polyconchoecia commixtus gen. et sp. nov.(Ostracoda:Myodocopa:Halocyprididae) from the South China Sea

Planktonic ostracods are small crustaceans abundant in marine ecosystem worldwide as appreciable part of marine zooplankton.Family Halocyprididae is a large group of halocyprid ostracods,and the tribe Conchoeciini has contained 21 genera previously.We described a further genus with a species Polyconchoecia commixtus gen.et sp.nov.from the middle of South China Sea in this study.The new species can be distinguished from related genera and species in having a unique combination of these characteristics:a lateral gland placed over right asymmetric gland and open near posterior margin;dense edge glands placed along ventral margin of carapace in line;shape of frontal organ;e-seta of first antenna is bare;endopod of second antenna has one small oval hump with central concave on mid-ventral margin,instead of processus mamillaris,exopod 1 has a small disto-dorsal spine,exopod 1 and 2 are fused,exopod 3 and 4 are bare;endopod 1 of mandible has one long ventral seta,endopod 2 has one ventral seta;maxillary endopod 1 has two basal setae;endopod 1 of fifth limb has only one ventral seta;endopod 1 of sixth limb and endopod 2 have no ventral seta.The definite distinctions in locations of major glands are the key characteristics of the new genus.