Molecular analysis of Rhipicephalus sanguineus (Acari: Ixodidae), an incriminated vector tick for Babesia vogeli in Taiwan.

The genetic identity of Rhipicephalus sanguineus tick was determined for the first time in Taiwan. The phylogenetic relationships were analyzed by comparing the sequences of mitochondrial 16S ribosomal DNA gene obtained from 32 strains of ticks representing six species of Rhipicephalus, two species of Dermacentor and two outgroup species (Haemaphysalis inermis and Ixodes ricinus). Seven major clades can be easily distinguished by neighbour-joining analysis and were congruent by maximum-parsimony method. All R. sanguineus ticks of Taiwan were genetically affiliated to the tropical lineage group of R. sanguineus sensu lato with highly homogeneous sequence (99.7-100% similarity), and can be discriminated from the temperate lineage group of Rhipicephalus sp. II and R. turanicus with a sequence divergence ranging from 1.7 to 5.2%. In contrast, the nucleotide variations among other Rhipicephalus spp. and other species/genus of ticks compared with the R. sanguineus ticks of Taiwan were measured from 10.6 to 25.5%. Moreover, intra- and inter-species analysis based on the genetic distance (GD) values indicated a lower level (GD < 0.003) within tropical lineage group compared with temperate lineage group (GD > 0.055) of Rhipicephalus, as well as other (GD > 0.129) and outgroup (GD > 0.236) species. Our results provide the first genetic identification of R. sanguineus ticks collected from Taiwan and demonstrate that all these R. sanguineus of Taiwan affiliated to the tropical lineage group of R. sanguineus sensu lato.