Two new species of the genus Heteropsyllus (Crustacea, Copepoda, Harpacticoida) from Jeju island, Korea and Devon, England

During a study of the harpacticoid copepods from off Jeju Island, in the South Sea of Korea, a new species of the genus Heteropsyllus was discovered. Heteropsyllus coreanus sp. nov. differs from its congeners in the following combination of characters: a pointed apex of rostrum; areolated ornamentation of the cephalothorax; a single basal seta on the maxillule and the shape of the fifth thoracopod in the female. This is the first record of the genus Heteropsyllus from Asia. The second new species is described from specimens in the Norman collection in the Natural History Museum, London (NHM). Heteropsyllus celticus sp. nov. was originally identified as H. curticaudatus by Norman, however this new species is distinguishable from H. curticaudatus T. Scott (1894) by having reticulated ornamentation on the cephalothorax, a strong seta on the proximal endite of the maxilla, only one seta on the exopod of the mandibular palp, and a different armature formula of the swimming legs. This study reveals that the mouthpart structures of Heteropsyllus can be important in identifying the species of this genus, and should be re-examined in all other species of Heteropsyllus.