The ITS2 ribosomal DNA of Anopheles beklemishevi and further remarks on the phylogenetic relationships within the Anopheles maculipennis group of species (Diptera: Culicidae)

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Anopheles beklemishevi specimens from Russia were analysed by their ITS2 ribosomal DNA sequence to amend and to specify the phylogenetic tree of the Anopheles maculipennis species complex. Surprisingly, with 638 base pairs, the ITS2 regions of all the 34 An beklemishevi specimens examined were considerably longer than those of all their sibling species. Sequence alignment with GenBank derived sequences of the other siblings was only possible in the beginning (for approx. 335 bp) and at the end (for approx. 150 bp) of the PCR-amplified DNA fragment, whereas in the middle, the An beklemishevi DNA sequence found no counterpart in sequences of the other siblings. Closer analysis of this intermediate part suggests a duplicated insertion of about 140 bp that has undergone subsequent mutational changes. Due to this large putative insertion, computerized phylogenetic analysis by the Bayesian inference method locates An beklemishevi in a closer relationship to the nearctic than to the palaearctic sibling species. However, when only ITS2 regions are compared, that have corresponding sequences in the other siblings, An beklemishevi forms a lineage with the palaearctic species although it is still most remotely related. It is hypothesized that during the evolution An beklemishevi separated first from the common ancestor of the palaearctic species, which had presumably made its way from the Nearctic to the Palaearctic.