Whole body of male Argulus japonicus. A, Light micrograph. Note the melanophores patches (circles) scattered over dorsal surface of carapace lobes and abdomen. Compound eyes (square). Seminal vesicle (sv). Testis (ts). Note the rounded end of abdomen (arrows); B, Scanning electron micrograph of dorsal view. Compound eyes (circle in square). Abdomen separated by sinus (arrow); C, Scanning electron micrograph of ventral view. Not the pre-oral spine; D, Accessory copulatory projections on third leg (circle). a, abotomen; an, antennule; ant, antenna; c, carapace; l, swimming leg; max, maxilla; maxl, maxillule; p, proboscis; ps, preoral spine; sv, seminal vesicle; t, thorax; ts, testis.