The sperm of Matsucoccus feytaudi (Insecta, Coccoidea): Can the microtubular bundle be considered as a true flagellum?

In the present work the spermiogenesis and sperm structure of Matsucoccus feytaudi, a primary pest of the maritime pine in southern eastern Europe, is studied. In addition to the already known characteristics of coccid sperm, such as the absence of the acrosome and mitochondria, and the presence of a bundle of microtubules responsible for sperm motility, a peculiar structure from which the microtubule bundle takes origin is described. Such a structure - a short cylinder provided with a central hub surrounded by several microtubules with a dense wall - is regarded as a Microtubule Organizing Centre (MTOC). During spermiogenesis, quartets of fused spermatids are formed; from each spermatid, a bundle of microtubules, generated by the MTOC, projects from the cell surface. Each cell has two centrioles, suggesting the lack of a meiotic process and the occurrence of parthenogenesis. At the end of the spermiogenesis, when the cysts containing bundles of sperm are formed, part of the nuclear material together with the MTOC structure is eliminated. Based on the origin of the microtubular bundle from the MTOC, the nature of the bundle as a flagellum is discussed.