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.

Molecular phylogeny of Anopheles hyrcanus group (Diptera: Culicidae) based on mtDNA COI

“…Thus, it is important to devise an efficient and accurate method to identify members of the Hyrcanus Group [15], which is a prerequisite for malaria vector surveillance in practice [16, 17]. However, it is difficult to distinguish cryptic species in the Hyrcanus Group by morphological features [5, 18] because there of 1) the scarcity of trained morphologists in the field [19] and 2) the loss of taxonomic traits during daily surveillance activities, such as wing scales [15, 20]. …”

“…Combined with morphological characteristics and molecular evidence [19, 21–23], the accuracy of mosquito identification has recently improved, both in fieldwork and scientific research. This was caused by 1) the rapid growth of molecular marker sequences in the GenBank database (http://www.ncbi.nlm.nih.gov/genbank/), 2) the consistency between barcoding results and traditional morphology-based taxonomy [24] and 3) the ability to extract enough deoxyribonucleic acid (DNA) for species identification by molecular methods from any life stage of individual mosquito [15, 25].…”

“…High divergence of intraspecific distance is probably caused by recent geographic isolation, suggesting the presence of cryptic species [28, 33]. Thus, more complete sampling of the geographic range, greater distance among sample locations, and more diversified the sampled individuals, the more accurate the genetic divergences within and among species [19, 27, 30, 34]. As such, it will be easier to distinguish cryptic species from studies based on large geographic range, especially cryptic species with short historical divergence [27, 35, 36].…”

Phylogenetic study of six species of Anopheles mosquitoes in Peninsular Malaysia based on inter-transcribed spacer region 2 (ITS2) of ribosomal DNA

“…Since the An. peditaeniatus ITS2 rDNA sequences from other countries that are archived in GenBank are too short [54], phylogenetic comparison of the An. peditaeniatus population could not be conducted.…”

Cytogenetic, hybridization and molecular evidence of four cytological forms ofAnopheles nigerrimus(Hyrcanus Group) in Thailand and Cambodia

“…Bayesian phylogenetic relationships among the 13 isolines of An. nigerrimus from Thailand and Cambodia based on ITS2 sequences compared with nine species of the Hyrcanus Group and three Hyrcanus‐group specimens from Kalimantan, Indonesia (Paredes‐Esquivel et al ). Numbers on branches are bootstrap values (%) of NJ analysis and Bayesian posterior probabilities (%).…”