Molecular evidence for the occurrence of a new sibling species within the Anopheles (Kerteszia) cruzii complex in south-east Brazil

BACKGROUND: Anopheles cruzii (Diptera: Culicidae) has long been known as a vector of human and simian malaria parasites in southern and south-eastern Brazil. Previous studies have provided evidence that An. cruzii is a species complex, but the status of the different populations and the number of sibling species remains unclear. A recent analysis of the genetic differentiation of the timeless gene among An. cruzii populations from south and south-east Brazil has suggested that the population from Itatiaia, Rio de Janeiro State (south-east Brazil), is in a process of incipient speciation. METHODS: A ~180 bp fragment of cpr, a gene encoding the NADPH-cytochrome P450 reductase, an enzyme involved in metabolic insecticide resistance and odorant clearance in insects, was used in this study as a molecular marker to analyse the divergence between five An. cruzii populations from south and south-east Brazil. RESULTS: Analysis of the genetic differentiation in the cpr gene revealed very high F(ST )values and fixed differences between Itatiaia and the other four populations studied (Florianópolis, Cananéia, Juquitiba and Santa Teresa). In addition, the data also provided preliminary evidence that seems to indicate the occurrence of two sympatric sibling species in Itatiaia. CONCLUSIONS: Population genetics analysis of An. cruzii samples from different localities using a fragment of the cpr gene suggests that the Itatiaia sample represents at least one new sibling species in this complex.