Sperm ultrastructure of the bees Exomalopsis (Exomalopsis) auropilosa Spinola 1853 and Paratetrapedia (Lophopedia) sp. Michener & Moure 1957 (Hymenoptera, Apidae, Apinae).

Abstract

The spermatozoa of Exomalopsis auropilosa and Paratetrapedia (Lophopedia) sp. are long and slender, measuring about 374 microm and 370 microm in length of which the head region measures approximately 25.8 and 28.3 microm, respectively. The head consists of an acrosome formed by an acrosomal vesicle covering a perforatorium, which presents a paracrystalline organization in Paratetrapedia (Lophopedia) sp. and a nucleus. This latter measures about 24 microm in Exomalopsis auropilosa and 27 microm in Paratetrapedia (Lophopedia) sp., and has compact chromatin. The nucleus is attached to the flagellum by an electron dense material and centriolar adjunct is observed between it and smaller mitochondrial derivative. In this flagellar region only one accessory body is observed, which occurs between the larger mitochondrial derivative and the axoneme. The flagellum consists in a typical axoneme, 9+9+2 microtubules, two mitochondrial derivatives and two accessory bodies. The two mitochondrial derivatives are asymmetric in both length and diameter, and paracrystalline material appears only in the larger mitochondrial derivative. The structure and ultrastructure of the spermatozoa of the bee species here described are similar to the majority of sperm found in the other Hymenoptera and may be a contribution for future phylogenetic analysis of Apidae.