Sperm ultrastructure of Podocotyloides magnatestis (Digenea, Opecoeloidea, Opecoelidae) a parasite of Parapristipoma octolineatum (Pisces, Teleostei)

The mature Podocotyloides magnatestis spermatozoon exhibits two axonemes of the 9 + “1” pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, spine-like bodies, an external ornamentation of plasma membrane, glycogen granules and an antero-lateral electron-dense material. These ultrastructural characteristics have already been described in the Opecoeloidea species studied so far. However, P. magnatestis spermatozoon is distinguished by the fact that its electron-dense material is laterally located on the side of the second axoneme. Moreover, the posterior spermatozoon extremity, characterized by the presence of the nucleus, is observed for the first time in the Opecoelidae.