Ultrastructure of the microsporidian Inodosporus octospora (Thelohaniidae), a parasite of the shrimp Palaemon serratus (Crustacea, Decapoda).

A parasite of the muscle of the shrimp Palaemon serratus has been examined by light and electron microscopy. Development occurs among myofibrils and induces ultrastructural alterations of the muscle fibers causing white discoloration. This microsporidian is characterized by uninucleate, later diplokaryotic and di-diplokaryotic meronts. The mother cell develops by rosette-like budding into 8 uninucleate sporoblasts, each containing 3 tape-like filaments attached to the wall that is enclosed in a persistent sporophorous vacuole. Each sporoblast gives rise to a uninucleate spore that possesses 3 elongated tape-like filaments attached to the spore wall, like spore tails. The morphological characters of the spores, redescribed in the present study, suggested that the spores belonged to Inodosporous octospora. The possibility that in the future members of Inodosporus sp. may be considered a new parasite group is discussed.