Genetic and morphological characterization of Ixodes apronophorus from Western Siberia, Russia

Genetic variability of I. apronophorus from Western Siberia, Russia was examined using the nuclear internal transcribed spacer 2 (ITS2) and mitochondrial 16S rRNA and cytochrome c oxidase subunit 1 (cox1) genes and compared to those of Ixodes persulcatus and Ixodes trianguliceps from the same site. The I. apronophorus sequences demonstrated the highest nucleotide and haplotype diversity for both mitochondrial genes, whereas I. persulcatus was more variable in the nuclear ITS2. Phylogenetic analysis of the molecular sequence data showed that I. apronophorus differed from other Ixodes species, including Romanian I. apronophorus. The level of identity between 16S rRNA gene sequences of Siberian and Romanian I. apronophorus was only 91%; these sequences did not form a monophyletic group, indicating that I. apronophorus from Siberia and Romania could be different tick species. The analysis of morphological features of the Siberian I. apronophorus confirmed their consistency with those for the previously described I. apronophorus species. Based on the 16S rRNA and ITS2 sequences, Siberian I. apronophorus clustered together with Ixodes kazakstani and Ixodes scapularis, which are the recognized members of the Ixodes ricinus-I. persulcatus species complex within the subgenus Ixodes, and can be assigned to this complex.