Background Reduvius iopterus Perty 1834 was first described from the Rio Negro, Brazil. It was then included in Zelus Fabricius 1803 as Z. iopterus (Perty 1834) without critical examination of this action (Stål 1872).The Neotropical genus Aristathlus Bergroth 1913 was described to include two species from the Amazon basin: A. imperatorius Bergroth 1913 and A. regalis Bergroth 1913.New information Based on the original description and illustration of Reduvius iopterus, Aristathlus imperatorius is considered to be its junior synonym, with the resulting new combination: Aristathlus iopterus (Perty 1834).