The Sperm Ultrastructure of the Nitidulidae Meligethes flavimanus (Stephens, 1830) and of the Phalacridae Olibrus affinis (Sturm. 1807) (Coleoptera Cucujoidea)

The sperm ultrastructure of two members of Cucujoidea was described. The Nitidulidae Meligethes flavimanus sperm are long cells extending along the cyst cell with a series of helicoidal tracts. Each sperm cell has a bi-layered acrosome, a cylindrical nucleus and two mitochondrial derivatives of unequal sizes, the one on the right side larger than the opposite one. The axoneme has the common 9+9+2 microtubule pattern and is flanked by two accessory bodies. The one on the right side has an extension of electron-dense material (a puff-like body) reaching the smaller mitochondrial derivative. The cytoplasm of the sperm cyst hosts numerous bacteria. The sperm of the Phalacridae Olibrus affinis are very long cells that form numerous foldings throughout the cyst. The sperm cell has a long bi-layered acrosome, a cylindrical nucleus and a conventional 9+9+2 axoneme. As in the previous species, two mitochondrial derivatives of different sizes are present, the one on the right side larger than the second one, only 1/3 of the other. Two accessory bodies are on both sides of the axoneme. That on the right side is very large, triangular shaped, while on the opposite side a small electron-dense dot is present. The study performed on the two species of Cucujoidea confirms a close phylogenetic relationship between this superfamily and those of Chrysomeloidea and Curculionoidea, a finding also supported by molecular data.