Abstract
The present paper deals with gonadal formation and sex succession based on histological observations in the wrasse, Cirrhilabrus temmincki Bleeker, from Suruga Bay. Gonads of the present species are in the undifferentiated stage in young fish ranging from 11.4 to 19.5mm TL. In fish ranging from 21.1 to 40.4mm TL, gonads begin to differentiate initially into ovaries, forming an early ovarian cavity of the parovarian type and no evidence is found for the existence of any primary male. Reproduction takes place from June to September. The minimal size of sexual maturation is thought to be about 50mm TL for females and about 88mm TL for males. The androgenic transformation generally starts after the completion of female's reproductive function and these females thus change sex rather slowly. Several intersexual gonads are found both before and after the reproductive season. Although the intersexual form which shows the normal course of protogynous sex succession is found after the reproductive season, a few fish change sex previous to the reproductive season from female to male but their gonads seem to function only as female during this season. On the other hand, a group which is formed only of young or small transitionals and secondary males is obtained in April. The role and significance of this occurrence in hermaphroditism are discussed. C. temmincki is established as a monandric and dimorphic species. All the fish which show the terminal phase are secondary males, but the others which show the initial phase form a complex consisting of females, transitionals, and secondary males. A marked elongation of the second ventral ray is seen only in males as the result of a positive correlation with body growth.
