Gonadal development and non-functional protogyny in a coral-reef damselfish, Dascyllus albisella gill

In gonads of the Hawaiian daseyllus Dascyllus albisella, irrespective of the final sex of individuals, developed an ovarian lumen and primary-growth-stage oocytes after an initially undifferentiated slate. From this ovarian state or from more differentiated ovaries, some gonads redifferentiated into testes. None of 117 individuals examined had a gonad containing degenerating vitellogenic oocytes and proliferating spermatogenic tissue. Eleven individuals had gonads containing degenerating cortical-alveolus-stage oocytes and developing spermatogenic tissue. nle size of these individuals overlapped with the female size range in which the majority of the females were still in the middle of the maturation process. They were absent fi om the larger size range where the majority of females had vitellogenic oocytes. This indicated that the transition toward maleness is likely to have occurred after the onset of cortical-alveolus stage, but before final oocyte maturation and spawning as females. Therefore the protogynous pattern of gonadal development was non-functional. There was no dimorphism in the sperm duct configuration, and all the testes were secondary testes reported for diandric, protogynous species with undelimited gonads. Very early development of an ovarian lumen appeared to have resulted in a secondary-male configuration in all testes, although redifferentiation into males appeared to have occurred before sexual maturity and spawning as Females. (C) 2001 The Fisheries Society of the British Isles.