GONAD STRUCTURE AND HERMAPHRODITISM IN THE GOBIID GENUS CORYPHOPTERUS (TELEOSTEI, GOBIIDAE)

Protogynous hermaphroditism has been demonstrated in three species of Coryphopterus (Gobiidae). Based on an examination of sexual patterns in seven additional congeners, protogyny appears to be widespread in this genus. Female-to-male sex change was experimentally confirmed in the three species: Coryphopterus lipernes, C. hyalinus and C. dicrus. A histological examination of gonad structure was carried out in another four species: C. alloides, C. eidolon, C. thrix and C. urospilus. Protogyny was indicated in all four by the presence of tissue masses associated with the ovary, which, in protogynous congeners, develop into testis-associated structures during sex change. Coryphopterus exhibits considerable geographical, morphological and ecological diversity. The apparent prevalence of protogyny in this genus suggests that hermaphroditism is an ancestral, rather than a recently derived, condition. In experimental C. hyalinus examined in this study, secondary testis development showed some differences from that seen in other Coryphopterus. This suggests that the separate species status currently given to C. hyalinus, and the similar-appearing congener, C. personatus, is valid.