Abstract
One new species and two new records of diastylid cumaceans (Crustacea: Cumacea) are described from the Yellow Sea, North West Pacific. The new species Diastylis inplicata sp. nov. resembles D. nitens Gamo, 1968, but it is characterized by a smooth antero-lateral margin of the carapace without ridges or spines. It is widely distributed either in the intertidal mud flats of the Korean West coast or in shallow waters of the eastern Yellow Sea. The other two diastylids are newly recorded in the faunal inventory of the Yellow Sea: Diastylis loricata Lomakina, 1955 and Diastylis paratricincta Kang and Lee, 1996.