RESUMEN
BACKGROUND The Nyssomyia genus and Lutzomyia subgenus include medical important species that are Latin American leishmaniases vectors. Little is known about the phylogenetic relationships of closely-related species in each of these taxonomic groups that are morphologically indistinguishable or differentiated by very subtle details. OBJECTIVES We inferred the phylogenetic relationships of closely-related species within both the Nyssomyia genus and the Lutzomyia subgenus using a cytochrome c oxidase subunit I (COI) fragment. METHODS The sampling was carried out from 11 Argentinean localities. For genetic analyses, we used GenBank sequences in addition to our sequences from Argentina. Kimura 2-parameter (K2P) genetic distance and nucleotide divergence (Da) was calculated between closely-related species of Nyssomyia genus, Lutzomyia subgenus and between clades of Lutzomyia longipalpis complex. FINDINGS The K2P and Da values within species of Nyssomyia genus and Lutzomyia subgenus were lower than the divergence detected between clades of Lu. longipalpis complex. The haplotype network analyses within Lutzomyia subgenus showed shared haplotypes between species, contrary to Nyssomyia genus with none haplotype shared. Bayesian inference within Nyssomyia genus presented structuring by species. MAIN CONCLUSIONS This study evidences the phylogenetic proximity among closely-related species within Nyssomyia genus and Lutzomyia subgenus. The COI sequences of Nyssomyia neivai derived from the present study are the first available in GenBank.