Diplectrum radiale (Quoy \& Gaimard, 1824) (Serranidae): A rare case of simultaneous hermaphroditism in a teleost fish

Abstract

This study generates, for the first time, information on the reproductive traits of the simultaneous hermaphrodite Diplectrum radiale. The specimens were captured bimonthly in two distinct ecosystems along the south-eastern Brazilian coast. The mature ovotestes were removed, preserved in formalin and examined using histological techniques. The results revealed indeterminate fecundity with asynchronous ovarian organization. All spermatogenesis occurs within cysts, and the spermatogonial distribution indicated an unrestricted testicular type. The testicular and ovarian tissues were separated from each other by different ducts, indicating no possibility of internal self-fertilization. The hydrated oocytes were stored in the accessory reproductive structure for at least 24hr. The presence of atretic hydrated oocytes within this structure and the positive periodic acid-Schiff reaction of the villi-like projections revealed the function of the ovary sinus as absorbing unspawned oocytes. The relative batch fecundity ranged from 62 to 209oocytes/g (126 +/- 42) for specimens from the coast and from 52 to 203oocytes/g (113 +/- 57) for those sampled in the estuary. The potential batch fecundity was linearly related to size, weight, and the gonadosomatic and hepatosomatic indices, revealing that these parameters significantly affect the reproductive potential of D.radiale.