Macunahyphes zagaia sp. nov. and M. araca sp. nov. are described based on imagines collected from the Amazon biome in Brazil. Specimens belonging to all species of the genus were examined and a diagnosis for each one is provided. Variation seen in the male imago of M. eduardoi is described, as well as the female and egg for the ﬁrst time. Together with M. eduardoi, the two new species share the presence of a basal swelling on segment II of the forceps, which raises important questions concerning the evolution of this character in Leptohyphidae. Finally, a re-deﬁnition of the genus is proposed.
taxonomy, mayfly, South America, Amazon Rainforest, aquatic insect.