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 24 hr. 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 209 oocytes/g (126 ± 42) for specimens from the coast and from 52 to 203 oocytes/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.

Recent Findings on Spawning Patterns and Recommendations for the Fishery Management of the Southern Red Snapper—Lutjanus purpureus (Poey, 1866)—On the Amazon Continental Shelf of Brazil

“…The POF is the remnant membrane of the oocyte that persists after spawning, which is an important indicator of the spawning period, and provides a measure of the age of the follicles, based on the degree of degeneration of this structure, which lasts 24 h, on average. During this period, it changes shape as it shifts from spawning to the total degeneration of the follicle [19][20][21][22]. The phases of this degeneration are classified as recent, intermediate, and old (Table 2; Figure 3).…”

“…Stages in the degeneration of the postovulatory follicle and their duration. Adapted from [19][20][21][22].…”

“…The characteristics of the POF and the timing of its degeneration phases have been analyzed in a number of different aquatic organisms [19][20][21][22][23][24][25][26][27][28][29], reinforcing the importance of understanding this cell phase to ensure the accurate delimitation of the spawning period. Given the lack of studies that have focused on the reproductive patterns of L. purpureus, and the urgent need for effective management measures for the stocks of this species, especially considering the commercial focus on the smaller individuals, the present study provides new insights into its reproductive parameters.…”