ULTRASTRUCTURE AND DEVELOPMENT OF AGMASOMA-PENAEI (MICROSPORA, THELOHANIIDAE) FOUND IN PENAEUS-NOTIALIS (CRUSTACEA, DECAPODA, PENAEIDAE) FROM SENEGAL

The microsporidium Agmasoma penaei is found in the shrimp Penaeus noti alis from Senegal. It attacks the gonads, hepatopancreas, heart, intes tine, nervous system and the muscles forming white cysts (xenomas). It is partly responsible for high mortality in Senegal shrimp farming. I ts merogonic stages are diplokaryotic and in direct contact with the c ytoplasm of the host cell. All sporogonic stages have unpaired nuclei. The sporogony is usually octosporoblastic. Sporoblasts and spores are contained within a sporophorous vesicle. The formation of sporoblasts does not occur by budding. The sporoblasts are segragated by fragment s of plasma membrane within the sporogonial plasmodium. Synaptonemal c omplexes are apparently absent. The spores have an anisofilar polar fi lament and a polaroplast with a finely lamellar anterior region and a vesicular posterior part.