REPRODUCTIVE-BIOLOGY OF THE GUITARFISH, RHINOBATOS-HYNNICEPHALUS

Reproductive biology of the guitarfish, Rhinobatos hynnicephalus, from Xiamen coastal waters is described. Males have two functional testes. Spermatogenic cells in different seminiferous follicles are at differ ent developmental stages while those in the same follicle are at the s ame stage. The development of claspers suggests that males mature at 3 80-400 mm TL. Females mature at 390-440 mm TL. Both ovaries are functi onal. The first generation of ovarian eggs reach mature size when 22-2 4 mm in diameter in April or May. The subsequent crop of eggs is ready for ovulation when the intrauterine embryos reach full term. The guit arfish is aplacentally viviparous. Longitudinal folds were observed on the internal wall of the uterus. Gestation takes one year and parturi tion takes place in June or July. Fecundity ranges from 2 to 9, with t he large females usually being more fecund. Of 29 embryos ranging from 52-157 mm TL, there were 15 females and 14 males indicating an embryo nic sex ratio 1:1.