Complete life cycle of the ostracod Euphilomedes nipponica (Myodocopida, Philomedidae)

Abstract

We describe the complete life cycle of the ostracod Euphilomedes nipponica Hiruta, 1976. This was completed by collecting individuals from the sea once a month over the course of a year and through the parallel rearing of individuals under laboratory conditions. Females developed their first brood in mid-April, with 20–40 first instar offspring being released in early May. Because adult males did not live long, adult females produced subsequent broods without re-exposure to males, producing up to four broods in total by releasing juveniles at 1-month intervals. First instar individuals reached the fourth instar stage in less than 2 months during which time they molted three times. Molting paused at the fourth instar stage; thus, all offspring from the first to fourth broods reached the fourth instar stage by October. All individuals that have reached the fourth instar stage resume molting to the fifth instar stage in mid-January in response to unknown environmental cues, such as photoperiod and water temperature. Adult males appeared in March slightly earlier than females, with females initiating brooding again in April. This detailed information is expected to contribute toward improving our understanding of the life history strategies and reproductive modes of ostracod crustaceans.