Ultrastructural aspects of the sporogony of Aggregata octopiana (Apicomplexa, Aggregatidae), a coccidian parasite of Octopus vulgaris (Mollusca, Cephalopoda) from NE Atlantic coast

Scanning and Transmission Electron Microscopy, and Atomic Force Microscopy techniques were used to study different topographic and cytological aspects of the architecture of the sporogonial stages of the eimeriorin coccidian Aggregata octopiana. Ultrastructural studies concerning the formation of sp oroblast, sporocysts and number of sporozoites were presented for the first time for this coccidian species. Sporocysts are 11 to 15 mu m in diameter, the wall is 0.25-0.35 mu m thickness in tangential section. The sporocyst wall surfaces present projections or spiny which are 0.32 mu m long. Each s porocyst contains probably 8 sporozoites. The microscopic analysis of the s piny sporocyst cover in A. octopiana, a very important diagnostic character for the taxon, makes it possible to clear up the diagnoses of the species, allowing the taxonomic reappraisal of A. spinosa Moroff, 1908 as a synonym y of A. octopiana Schneider, 1875.