Gametogênese e período de desova de Fossula fossiculifera (d’Orbigny, 1835) (Bivalvia : Mycetopodidae)

Abstract

Fossula fossiculifera (d’Orbigny, 1835) is a threatened freshwater mussel. The aim of this study is to describe the aspects of life history related to their reproduction. We tested the hypothesis that the variation among biometric parameters of female gametic elements is different among maturation stadiums of gametogenesis. The freshwater mussels were collected in the Córrego Baixo, Nobres, MT, from November 2016 to October 2017 and from January 2019 to October 2019. Histological techniques were used in to analyze of the gametogenesis and quantitative methods were used to test the hypothesis. The total length and the total weight of shells were measured to determine the categories of length and weight and the fecundity was estimated. The total length ranged between 47.49 mm and 98.02 mm and the total weight ranged between 11.90 g and 170.60 g. The population of F. fossiculifera is predominantly dioecious with a single specimen hermaphrodite. The sex ratio in the population did not significantly differ from 1:1. Four acini developmental stadiums were recognized: in maturation, mature, spawning and spent. The statistical analysis showed significant differences in perimeter variation and oocyte size among the stadiums. The gametogenesis is continuous with picks of spawning and gametes maturation between July and October. The mean fecundity was 1,207,258 embryos/individual. The findings of this study contribute to knowledge of reproductive and life history characters of the Mycetopodidae.