Pygocentrus ternetzi, originally described by Steindachner in 1908 from the Rio Paraguay near Descalvados, Mato Grosso, Brazil, is currently considered a synonym of Pygocentrus nattereri by most ichthyologists. The scientific community acknowledges that P. ternetzi is synonymous with P. nattereri; however, the name P. nattereri is often incorrectly applied to both red-breasted Amazonian piranhas and yellow-breasted species from the drainage of the Rio Paraguay.
