Phylogenetic and haplotype network analysis of Ixodes crenulatus, Ixodes canisuga, Ixodes acuminatus and Ixodes redikorzevi (subgenus Pholeoixodes) from their geographical range, Europe and China

Ixodes crenulatus and Ixodes acuminatus (subgenus Pholeoixodes) have a broad Palearctic distribution, ranging from Europe to Asia (northern China). This research aimed to explore the phylogenetic relationships and haplotype diversity of these two tick species from Europe, and the Xingjiang Uygur Autonomous Region (XUAR, northwestern China). For this, part of the cytochrome c oxidase subunit I (cox1) gene was amplified, sequenced and compared involving ten specimens of I. crenulatus (n = 8) and I. acuminatus (n = 2) collected in XUAR, as well as sequences of Ixodes canisuga (n = 15), I. acuminatus (n = 13) and Ixodes redikorzevi (n = 6) from Europe retrieved from GenBank. Phylogenetic analysis was performed using MEGA 7.0 program. Haplotype analysis was performed with the DNAsp v5.10.1 program. I. crenulatus and I. canisuga ticks share a common ancestor with a genetic distance of ≤ 0.01. The I. crenulatus ticks from XUAR showing 99.5% sequence similarity with those from Russia. A total of 13 haplotypes and 2 groups of I. canisuga and I. crenulatus were identified, with a genetic diversity of 0.9474 (h) and a nucleotide diversity of 0.0067 (π). I. acuminatus and I. redikorzevi form sister clades with a genetic distance of ≤ 0.02. A total of 12 haplotypes and 5 groups of I. acuminatus and I. redikorzevi were found, exhibiting a genetic diversity of 0.9474 (h) and the nucleotide diversity was 0.0093 (π). I. crenulatus from Russia and XUAR can be grouped into a single clade. The I. acuminatus H-1 haplotype from XUAR was grouped with H-5 haplotype from Spain and H-7 haplotype from Malta according to GenBank data available.