Abstract
The reproductive system of Mothocya renardi (Bleeker, 1857), a protandrous hermaphroditic cymothoid that infects the belonid fish Strongylura leiura Bleeker, 1850, is characterized using light and electron microscopy. Three protandrous hermaphroditic adult phases are identified: male, transitional and female. Each phase includes a paired reproductive system, one on either side of the gut. Each consists of three lobed testes, followed by an ovary, then a vas deferens that opens into a penis on the same side. During the male phase, all testis lobes are filled with germ cells at various stages of spermatogenesis and spermeogenesis. Primary and secondary spermatogonial cells are confined to the peripheral side of the testis lobe. The ovary shows peripheral germarium and a large number of yolkless oocytes encircled by follicle cells. The oviduct emerged from the ovary mid laterally and its distal end was found to be sealed. The exceptionally elongated spermatozoon consists of a head and a long filamentous tail. The spermatozoa are found organized into characteristic bundles to form spermatophores, and these are also packed in the vas deferens during the male phase. During the transitional phase, on the other hand, testes appear to be withered, but the vas deferens contains spermatophores. The ovary shows yolky oocytes encircled by follicle cells. During the female phase, the testis lobes appear as thin, empty, and sac like, and the extremity of the vas deferens is closed. Ovaries contain yolky oocytes and more prominent oviducts than male and transitional phases. The present paper also discusses the pattern of correlation between 1) the ovarian and brood cycles and 2) the ovarian and molt cycles.