Structure and ultrastructure of spermatozoon in six species of Drosophilidae (Diptera)

Abstract

The Drosophilidae family is formed by Brachycera Diptera distributed widely across different regions of the planet. It is composed of about 4000 species, 304 of which are found in Brazil. The objective of this work was to characterize morphologically the structure of the male internal reproductive apparatus and the ultrastructure of the spermatozoon in four Neotropical (Drosophila cardini, D. mercatorum, D. nebulosa and D. sturtevanti) and two invasive (D. simulans and Zaprionus indianus) species of drosophilids. The structural aspect of the internal reproductive apparatus corresponds with that described for other drosophilids; however, there are differences in the size and coloration of the structures, such as the testes, in each species analyzed. The spermatozoon of these species was seen to be long and fine, presenting morphological variation. The ultrastructure of the spermatozoon revealed that the morphological pattern is similar to that found in the majority of insects. The head region presents a nucleus with condensed chromatin and the acrosome positioned laterally to the nucleus. In the tail region, the axoneme presents the 9+9+2 pattern commonly described for other species of Diptera. The species presented differences regarding the shape and size of the mitochondrial derivatives. Cytochemical analysis using EPTA also revealed differences in terms of the location of the basic proteins in the mitochondrial derivates. The results obtained contribute to expanding the database for the Drosophilidae family, providing information that may contribute to intra- and inter-specific identification and supplying phylogenetic analyses.

Keywords: Drosophila cardini; Drosophila mercatorum; Drosophila nebulosa; Drosophila simulans; Drosophila sturtevanti; Morphology; Zaprionus indianus.