FEMALE REPRODUCTIVE-BIOLOGY AND OOCYTE DEVELOPMENT OF THE RED FROG CRAB, RANINA-RANINA, OFF HACHIJOJIMA, IZU-ISLANDS, JAPAN

Specimens of the red frog crab, Ranina ranina. examined in this study were collected off Hachijojima. Japan from 1987-1988 and 1990-1991. Ov igerous females occurred from May to September, and their carapace len gth ranged from 61.8 to 102.1 mm. Minimum size at the maturity was est imated to be 50 to 60 mm carapace length. The lobule-type ovary had a longitudinal ovarian cavity at the center. Germinal zones were located along the sides of the cavity. Oogenesis was divided into five main a nd ten detailed stages: proliferation (oogonium); previtellogenesis (b ouquet, early chromatin nucleolus, late chromatin nucleolus); primary vitellogenesis (oil globule and yolk granule); secondary vitellogenesi s (primary yolk platelet, secondary yolk platelet and prematuration); and maturation (maturation) stages. Vitellogenesis started at the oil globule stage when weakly positive periodic acid-Schiff granules appea r in the cytoplasm. Based on the gonadosomatic index and histological changes in ovary, the reproductive cycle was divided into five stages: multiplication, from December to January; developing, from February t o March; ripe in April and early May; spawning, from late May to Augus t; and recovery, from August to November. Each crab spawned more than once during the spawning season.