Desenvolvimento ovocitário e testicular de Rhamdia voulezi e Steindachneridion melanodermatum, espécies endêmicas do rio Iguaçu, Paraná-Brasil

Abstract

The aim of this study was to verify the oocyte and testicular development of two species Rhamdia voulezi and Steindachneridion melanodermatum. For R. voulezi, 500 fish with four months old and average weight of 11.70 g were stocked in cages (TR) and collected monthly, for S. melanodermatum, 170 fish with four years old and average weight of 799.06 g were distributed into two cropping systems, pond (VE) and TR, and collected bimonthly. The collected animals were euthanized, weighed, measured and gonads evaluated macro and microscopically. We calculated the gonadosomatic (GSI) and hepatosomatic index, abdominal fat and condition factor &#916;K. The gonads fixed in Bouin solution were dehydrated, diaphanized and embedded in paraplast. The sections of 5&#956;m, stained by technique HE. In both species, gonads are pairs structures located dorsally in region of the abdominal cavity and fused in posterior extremity forming the oviduct and sperm duct. In R. voulezi, the ovarian development was classified in phases such as immature, development (initial, intermediate and final), capable to spawning and regression, and testicular development in phases such as immature, development, capable to release sperm and regeneration, with females in the capable spawning phase in the months from December to March, period with the highest values of IGS and &#916;K. For S. melanodermatum, females and males collected in VE showed the highest values of weight and total length on collection period (p<0.05), however it was not verified macro and microscopic difference in the ovaries and testicles of animals on VE or TR, being determined four phases for gonadal development (immature, developing, capable spawning/release sperm and regeneration). Females and males of S. melanodermatum capable to spawning were collected from October to December, period with the highest values of IGS and &#916;K. In testicle of S. melanodermatum was evidenced ovarian follicles in primary growth.