Release, behavior and phylogenetic significance of spermatozoa in bundles in the seminal vesicle during sexual maturation in Aculeata (Hymenoptera)

RESUMO

In this report, we describe how spermatozoa are released in the Aculeata Melipona quadrifasciata (Apidae) and Acromyrmex subterraneus (Formicidae). Immature and sexually mature adult males of both species were dissected and their seminal vesicles, vas deferens and testes were processed for light and transmission electron microscopy. At the end of spermatogenesis, the spermatozoa still formed bundles, with the anterior end of their heads inserted into electron dense material. These bundles migrates to the seminal vesicles and, as the adults matured sexuality, the bundles started to disorganize and the spermatozoa became separeted. At the end sexual maturation, the seminal vesicles contained no bundles, but were completely full of free spermatozoa. In the Symphyta, as in the Aculeata studied here, the spermatozoa leave the testis in bundles. But there is no dissociation of spermatozoa from the bundles during sexual maturation. The Aculeata have been suggested to be derived from parasitic wasps that, in turn, derived from the Symphyta. Hence, the release of spermatozoa in bundles in the Aculeata is reverse characteristic or may indicate that this group is derived directly from the Symphyta.