The male imago of Americabaetis longetron Lugo-Ortiz & McCafferty is described based on nymphs reared on field in the municipality Alfredo Chaves, Espírito Santo state, Brazil. The species can be distinguished from the others male imagos of the genus by the following combination of characters: 1) turbinate eyes uniformly separated from each other, upper surface ellipsoidal; 2) terga with a light yellowish brown band along midline; 3) genitalia with first segment distinctly constricted medioapically; 4) length of body relatively long (6.3 mm). The first key to the male imagos of the genus is also proposed.
Taxonomy; identification key; Espírito Santo; Neotropics
