Relationship of ovarian and marsupial development to the female molt cycle in Acanthomysis robusta (Crustacea: Mysida)

In the present study, the relationship of ovarian development and marsupial develop-ment to the female molt cycle was examined in Acanthomysis robusta (Crustacea: Mysida). Yolk accumulation in ovaries started at stage C and advanced during stages D sub(0)-D sub(2) of the female molt cycle. As females at stages A-B exhibited newly spawned eggs in their marsupia and non-developed ovaries, oviposition likely occurred at stage A of the molt cycle. Larvae in the marsupia were at the egg-shaped embryonic stage during the female molt stages A-C. Larval hatching occurred at stage C, and the larvae were at the nauplioid stage during stages C-D sub(1) of the female molt cycle. Larvae at the postnauplioid phase appeared at stage D sub(1), indicating that naupliar molting occurred in stages D sub(0)-D sub(1) of the female molt cycle. At stage D sub(2), empty marsupia were observed, and any remaining brood were at the postnauplioid phase, suggesting that young are released at stage D sub(2) of the female molt cycle. The brood size (8-53 embryos and larvae) was significantly correlated to female carapace length. These results indicate that ovarian development and marsupial development are closely related to the female molt cycle of A. robusta.