Nyssomyia umbratilis (Ward & Frahia) is the main vector of Leishmania guyanensis in the Brazilian Amazon region, where it is widely distributed. Studies have hypothesized that this phlebotomine is part of a cryptic species complex, spatially delimited by the Amazonian river systems, and with different transmission potential of L. guyanensis. In the present study, the immature stages of N. umbratilis are described from laboratory-reared specimens originating from the states of Amazonas and Pará, Brazil. Based on scanning electron and optical microscopy examinations, fine morphological structures (eggshell, setae, and mouthparts of larvae and pupae) are presented. A new form of sandfly pupae sexing (non-invasive) is also provided. The correct identification of insect is extremely important for the epidemiology of certain diseases. However, only the morphological characters of adult can be insufficient to separate accurately the closely related species. It is expected that the present description may contribute to solve the taxonomic problem involving N. umbratilis.
Keywords: Taxonomy; chaetotaxy; cutaneous leishmaniasis; scanning electron microscopy.