The imagos of some enigmatic members of the Hermanella complex (Ephemeroptera, Leptophlebiidae).

The imago stages of three species of the Hermanella complex are described mostly based on material from Roraima, northern Brazil: Hydrosmilodon gilliesae, Hydromastodon sallesi and Leentvaaria palpalis. Male imagos of Hydrosmilodon gilliesae and Leentvaaria palpalis both have a pair of large, broad projections at the posterior margin of the styliger plate, nearly covering the penis lobes; in Leentvaaria palpalis, however, these projections are fused. The male imago of Hydromastodon sallesi resembles Hydrosmilodon plagatus in that both species have a styliger plate with a robust projection that is curved towards the penis lobes. DNA barcoding is likely to be a powerful investigative tool for identifying and understanding species limits among these Ephemeroptera taxa, especially if it is used within an integrative taxonomic context. An updated identification key to the genera of the Hermanella complex is proposed.