Molecular taxonomy of members of the Anopheles hyrcanus group from Thailand and Indonesia

Abstract

During studies of malaria vectors in Indonesia and Thailand, several specimens identified by field staff as members of the Anopheles barbirostris group (Diptera: Culicidae) were found to belong to the Anopheles hyrcanus group, as shown by marked differences in the size of the nuclear rDNA second internal transcribed spacer (ITS2) between the barbirostris (~1500 bp) and hyrcanus (~600 bp) groups. Identification of the species concerned required a more detailed study of ITS2 sequences and subunit I of the mitochondrial DNA cytochrome oxidase gene (COI). A phylogenetic analysis, based on Bayesian methods, revealed that the hyrcanus group specimens comprised five distinct clades, two of which corresponded with known species, Anopheles peditaeniatus and Anopheles sinensis. The remaining specimens formed three additional clades, for which there are no similar sequences in GenBank and which cannot be linked to previously described species. The misidentification of hyrcanus group species has important implications for malaria vector control; more comprehensive studies employing gene sequences are required to clarify the number of species in the group, their distribution and vector status.