Abstract
Twelve late-stage phyllosoma larvae of Chelarctus cultrifer (Ortmann, 1897) were collected in the offshore area northeast of Yonaguni Island on 23 November 1998, transported to the laboratory, and reared individually in circular acrylic chambers on a diet of fresh clam meat. Two final-stage phyllosomas metamorphosed into the nisto stage after 14 and 30 days, and these nistos then molted to the juvenile stage after 10 and 11 days, respectively. The morphology of the late-stage phyllosomas collected off Yonaguni Island, other phyllosomas from the Northwestern Pacific, and the nisto and juvenile stage exuvia of the reared larvae are described and illustrated in detail.