| Abstract: | The first aflagellate and immotile Coleopteran spermatozoon is described in a group of species belonging to the family Ptiliidae. The mature spermatozoon is devoid of flagellum, centrioles and mitochondria, includes a three-layered acrosomal complex (extraacrosomal layer, acrosome and perforatorium) and a long nucleus made up of two regions of different densities. A compact submembranary capsule and a thick glycocalyx are also present. Motility organelles are absent during the whole spermiogenesis, which is not regressive. The new structures peculiar for this type of sperma are designed for protection. No other sperm models with these characteristics have been described so far. |
