A new myxoporean species is described from a freshwater fish in Brazil. Myxobolus absonus sp. n. was found infecting Pimelodus maculatus captured in the river Piracicaba, State of Sao Paulo, Brazil. Cysts were found free in the opercular cavity. The spores are large (length-15.7 +/- 1.5 mum, width-10.2 +/- 0.7 mum; mean +/- S.D.) and oval in shape, with the anterior end slightly pointed. The spore valves are relatively thin, smooth, and asymmetrical in a frontal view. The polar capsules are pyriform in shape, and unequal in size; the largest are 6.4 +/- 0.7 mum long and 3.6 +/- 0.5 mum wide, while the smallest are 4.2 +/- 0.6 mum long and 2.5 +/- 0.5 mum wide.9717980