Morfologia do sistema reprodutivo de Scoloplax dolicholophia Schaefer, Weitzman & Britski, 1989

Abstract

The diversity of fishes and aquatic habitats led to adaptations that are reflected in strategies and thus in the morphology of reproductive structures. In the same way, the target species of this study belongs to the order of the Siluriformes, the family Scoloplacidae for which it is suggested the occurrence of sperm insemination and storage by females, a rare condition among fish. With this, the objectives of this work were to characterize the reproductive system of Scoloplax dolicholophia morphologically; to describe the morphological characteristics of the reproductive apparatus of males and females, as well as to relate the development of the reproductive apparatus with the size of the individual and to verify if internal insemination occurs. For this, 56 specimens of the INPA Fish Collection were analyzed, from which biometric information (CP) and external morphology of the reproductive organ were analyzed. Histological analysis of the female gonads was carried out to inspect the spermatozoa and identify the spermatozoa gonadal The results showed that both males and females of S. dolicholophia have genital papilla as copulatory organ, and that this structure is present throughout the life cycle of the individual, however, it develops differently between the sexes. In males the papilla has an elongated and turgid tubular form, in females, this structure is divided into two parts. The analysis of the standard lengths (R² = 0.7285) and the male specimens in relation to the size of the papillae showed that as the males grow their papilla increases in length. In females this relation was not strong considering the size of the structure with standard lengths (R² = 0.3531). Internal insemination was not confirmed for S. dolicholophia, since no spermatozoa were found in any of the females. In short, this species has a marked dimorphism in the reproductive tract which in the male appears to develop along with the growth of the individual, the mode of reproduction of S. dolicolophia not elucidated in this study, indicates that future studies with histological analyzes in a broader sampling in different temporalities and degrees of maturity of females may help.