Gonadal structure and population characteristics of the protogynous goby Coryphopterus glaucofraenum

Samples of Coryphopterus glaucofraenum were collected off the southwest coast of Puerto Rico and examined histologically to determine the sexual pattern. The sex ratios observed were female-biased. Experimental evidence showed that C. glaucofraenum is protogynous, with all-female groups undergoing sex change within 10 to 40 days.Histological studies on immature fish showed that all male fishes pass through a female stage. Ovarian, trnsitional and testis stuctures were similar to C. nichosi and C. personatus. The results indicate that protogyny is an ancestral condition in the genus Coryphopterus.