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

Abstract

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 sporoblast, sporocysts and number of sporozoites were presented for the first time for this coccidian species. Sporocysts are 11 to 15 μm in diameter, the wall is 0.25-0.35 μm thickness in tangential section. The sporocyst wall surfaces present projections or spiny which are 0.32 μm long. Each sporocyst contains probably 8 sporozoites. The microscopic analysis of the spiny 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 Moroif, 1908 as a synonymy of A. octopiana Schneider, 1875.