Variations in the adult male reproductive system among different groups of Hymenoptera
offer characteristics that help studies on behavior and phylogenetics. The objective of this study was
to describe the adult male reproductive system of three Trypoxylon (Trypargilum) species. For that,
tissues were disseced, fi xed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer, pH 7.2 and
postfi xed in 1% osmium tetroxide. The material was dehydratated and embedded for light and electron
transmission microscopes. The species have similar reproductive systems, which are formed by a pair
of testes, each one with three fusiforme follicles, from which emerges an efferent duct that later joins
forming a deferent duct. The deferent duct opens into an ejaculatory duct. The fi rst half of the deferent
duct is enlarged and differentiated in a region specialized in sperm storage, the seminal vesicle. The
accessory gland fl ows in the post-vesicular region of the deferent duct. The testes and vesicles are both
covered with a conjunctive capsule. Sexually mature individuals have all spermatogenesis stages in their
follicles. Sperms are released from testes in bundles which are disorganized inside seminal vesicles.