The sperm of Hexagenia (Pseudeatonica) albivittaWalker (Ephemeroptera: Fossoriae: Ephemeridae)

• Published in: Acta zoologica (Stockholm) 2015-04, Vol.96 (2), p.160
• Main Authors: Brito, Pedro, Mancini, Karina, Salles, Frederico Falcão, Rizzi, Evandro Apolinario, Dolder, Heidi
• Format: Article
• Language: English
• Subjects: Entomology; Insects; Morphology; Sperm
• ISSN: 0001-7272; 1463-6395
• DOI: 10.1111/azo.12063

This study describes the sperm morphology of the mayfly Hexagenia (Pseudeatonica) albivitta (Ephemeroptera). Its spermatozoon measures approximately 30 µm of which 9 µm corresponds to the head. The head is composed of an approximately round acrosomal vesicle and a cylindrical nucleus. The nucleus has two concavities, one in the anterior tip, where the acrosomal vesicle is inserted and a deeper one at its base, where the flagellum components are inserted. The flagellum is composed of an axoneme, a mitochondrion and a dense rod adjacent to the mitochondrion. A centriolar adjunct is also observed surrounding the axoneme in the initial portion of the flagellum and extends along the flagellum for at least 2 µm, surrounding the axoneme in a half-moon shape. The axoneme is the longest component of the flagellum, and it follows the 9+9+0 pattern, with no central pair of microtubules. At the posterior region of the flagellum, the mitochondrion has a dumb-bell shape in cross sections that, together with the rectangular mitochondrial-associated rod, is responsible for the flattened shape of the flagellum. An internal membrane is observed surrounding both mitochondrion and its associated structure.