ULTRASTRUCTURAL DATA ON THE LIFE-CYCLE STAGES OF MYXOBOLUS-BRAZILIENSIS N-SP, PARASITE OF AN AMAZONIAN FISH

A myxosporidium was found in the gills of Bunocephalus coracoideus, a freshwater fish from the Amazon River near Belem (Brazil) and studied using light and electron microscopy. Sporogenesis follows the usual pa ttern known in polysporic myxosporidians, giving rise to disporic pans poroblasts. The plasmodial wall presents a very sinuous outline with p rojections resembling villosities, unusual for histozoic species. Duri ng valvogenesis, one of the valves in the sutural ridge curves inwards and some microtubule bundles differentiate. The sporoplasm contains n umerous sporoplasmosomes with unique ultrastructural features. Based o n the morphologic aspects and specificity of the host species, we prop ose the creation of a new species, designated Myxobolus braziliensis n . sp.