Morphology of the male reproductive system and seasonality in reproduction in the freshwater crab Arcithelphusa cochleariformis (Brachyura: Gecarcinucidae)

ABSTRACT This study detailed the histomorphology of the male reproductive system and seasonality in the reproduction of a recently described genus and species of freshwater crab Arcithelphusa cochleariformis. Results indicated that the testis and vas deferens underwent correlative changes in accord with the active, inactive and revival phases of spermatogenesis. The spermatogenic activity was at its peak during June evinced from large fully extended acini with full package of mature spermatozoa and low during September–February with decreased acinar dimensions, pycnotic germ cells and residual sperms. Seasonal cyclicity was also observed in the thickness of epithelium, muscle layer, diameter of lumen and the amount of luminal contents of the vas deferens. In June, the anterior and middle vas deferenswere filled with secretions and spermatophores.By September, ruptured spermatophores with freely dispersed pycnotic spermatozoa were perceptible in the anterior and middle vas deferens and lysed spermatophoric debris in posterior vas deferens.