Laboratory Rearing of Ascothoracidan Nauplii (Crustacea : Maxillopoda) from Plankton at Okinawa, Japan

Abstract

Seven ascothoracidan nauplii of instars II-IV and one ascothoracid-Iarva were captured in inshore plankton at Sesoko Island, Okinawa, Japan, and the nauplii reared in the laboratory until, in two cases, they metamorphosed into ascothoracid-larvae. Naupliar instars II-VI and the ascothoracid-larvae are described and compared to larvae of Baccalaureus falsiramus Ito & Grygier from Tanabe Bay, Honshu, which they closely resemble. Pigmented structures in the ascothoracid-larvae possibly represent vestigial compound eyes. Competing hypotheses about the claw guard and proximal sensory process of ascothoracidan antennules are discussed in light of new ontogenetic data.