No abstract

The sand fly, Lutzomyia longipalpis (Lutz & Neiva) reputedly is a complex of cryptic species; however, there is currently no consensus as to the number of species in the complex or their geographic distributions. We conducted phylogenetic analyses of 31 populations from throughout the species range, using seven isozyme loci and genes in the mitochondrial genome. Analyses of these two independent sets of markers were largely concordant and revealed four distinct clades that support the existence of four species. The four clades have distinct geographic ranges: (1) Brazil (Species A = Lu. longipalpis sensu stricto), (2) Laran (Species B = Lu. pseudolongipalpis), (3) cis-Andean (Species C), and (4) trans-Andean (Species D). The cis-Andean clade may be subdivided further into two groups, one in Colombia and one in northwestern Venezuela, but their taxonomic status remains unresolved. Knowledge that Lu. longipalpis is a complex of species may ultimately shed light on anomalies in the epidemiology of visceral leishmaniasis in the New World.

Lutzomyia pseudolongipalpis, the first new sand fly species within the longipalpis complex, is described based on females and males from La Rinconada, Curarigua, Lara State, Venezuela. Similar to Lutzomyia longipalpis sensu lato, females of the new species show spermathecae with 8-10 annulations and cibarial armature with 8-12 horizontal teeth. However, L. pseudolongipalpis females show conspicuous vertical cibarial teeth, large stipites and wing vein sections, round cerci, and short and broad valvifers that separate them from L. longipalpis s. l. females. L. pseudolongipalpis and L. longipalpis s. l. males are isomorphic, both having parameres with two curved setae on a simple tubercle. The analysis of morphometric characters and their diagnostic value is in progress.

Lutzomyia longipalpis (Lutz & Neiva) is the primary vector of visceral leishmaniasis in Venezuela. An analysis of alleles at seven enzyme-encoding loci among four populations from different geographic and epidemiological regions revealed strong genetic substructuring. Isozyme analysis indicated that L. longipalpis in Venezuela is a complex of at least two subspecies. Possible differences in population size during their evolutionary histories, varying colonization histories and geological events may explain discrepancies in the patterns of variation observed at genetic markers between these four populations.