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

Abstract

In the present study, the relationship of ovarian development and marsupial development to the female molt cycle was examined in Acanthomysis robusta (Crustacea: Mysida). Yolk accumulation in ovaries started at stage C and advanced during stages D0-D2 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-D1 of the female molt cycle. Larvae at the postnauplioid phase appeared at stage D1, indicating that naupliar molting occurred in stages D0-D1 of the female molt cycle. At stage D2, empty marsupia were observed, and any remaining brood were at the postnauplioid phase, suggesting that young are released at stage D2 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.