Although the phlebotomine sandfly Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) is generally accepted to be a species complex, it is unclear how many members there are, how they are related and which are the main vectors of leishmaniasis. The vectorial capacity of each sibling species is likely to differ, thus a means of identifying the most important vector species is of critical importance to the epidemiology and control of this debilitating disease in South and Central America. In Brazil four chemotypes have been distinguished by sex pheromone analysis. In this study the sex pheromone extracts of L. longipalpis from six regions of Brazil were analysed in detail. Samples included the sympatric 1-spot, 2-spot and intermediate spot morphotypes from Sobral, Ceará State. The results strongly suggest that members of the complex that produce different sex pheromones are reproductively isolated, thus strengthening the argument that the different chemotypes represent true sibling species. The study also found significant differences in morphology and the amounts of sex pheromone produced by members of each chemotype from different parts of Brazil, which suggests population substructuring that has not previously been recognized. Evidence of a fifth chemotype in Brazil is also presented.