Anatomy and histology of the male reproductive tract in giant water bugs of the genus Belostoma Latreille, 1807 (Heteroptera, Belostomatidae)

Abstract

Giant water bugs (Belostomatidae) are widespread in the tropical and subtropical regions and have important ecosystem functions. This study describes the structure of the male reproductive tract in three species of Belostoma Latreille, 1807. The reproductive systems of sexually mature males of B. plebejum, B. stollii and B. testaceopallidum have a pair of globular testes, deferent ducts, seminal vesicles, an ejaculatory duct and an aedeagus. Each testis has five folded follicles, and each follicle is continuous with an efferent duct (0.72 cm in length on average), which opens together in the deferent duct (0.85 cm in length on average). Inside the testis follicles, germ cells develop synchronously in cysts with seven mitotic and two meiotic cycles. The deferent ducts have a dilated portion for the storage of spermatozoa, the seminal vesicles. Accessory glands were absent. The morphological characteristics of the male reproductive tract in these three species of Belostoma and their similarities with other aquatic Heteroptera are discussed.