PLATYCOPIAORIENTALIS, NEW SPECIES (COPEPODA: PLATYCOPIOIDA), FROM THE NORTH PACIFIC, WITH DESCRIPTIONS OF COPEPODID STAGES

Abstract

ABSTRACT A hyperbenthic copepod, Platycopia orientalis, new species (Platycopioida), collected from sandy bottom off Okinawa, southern Japan, is described together with its copepodid stages III― V. This is the first record of the order Platycopioida in the Indo-Pacific region. The paired gonopores are located ventromedially on the genital somite in females and ventrodistally in males. The developmental patterns of the antennules and legs 1-5 are unique compared with the common pattern in copepods. The distal 14 segments of the antennules are constant from CIII-CVI in the female, whereas fusion of segments in the male occurs at the molt from CV to adult. The addition of segments to the endopod and exopod of leg 1 and to the endopods of legs 2-4 is suppressed during the last molt. The proximal spine on the first exopod segment of legs 3, 4, and 5 appears at CIV, CV, and CVI, respectively, one molt after the separation of the segment which carries it.