Integrative taxonomy and species delimitation of Rhipicephalus turanicus (Acari: Ixodida: Ixodidae)

Rhipicephalus turanicus ticks are widely distributed across the Palearctic and Afrotropics. These two continental populations display differences in morphological characters that raise the question of a potential species boundary. However, the taxonomic status of these morphologically divergent lineages is uncertain because R. turanicus from Cyprus and Zambia have been shown to interbreed and produce fertile hybrids. We employ integrative taxonomy that considers data from mtDNA sequences (12S and 16S rDNA), geographic distribution, traditional (qualitative) morphology, as well as shape outlines of female spiracles and male adanal plates measured in a geometric morphometric framework (quantitative morphology) to resolve this taxonomic issue. Molecular lines of evidence (12S and 16S rDNA) support taxonomic separation between ticks sampled in the Afrotropics and the Palearctic. This is corroborated by qualitative and quantitative morphology. Within the Palearctic, two sub-lineages were recovered based on sequence data that loosely correspond to southern Europe and the Middle East/Asia. One new species, Rhipicephalus afranicus n. sp. is described from South Africa with a geographic distribution that extends into eastern Africa. This leaves R. turanicus sensu lato comprised of two lineages located in southern Europe and the Middle East/Asia. The type locality for R. turanicus is in Uzbekistan, thus the Middle East/Asia lineage is considered R. turanicus sensu stricto. Detailed descriptions are provided for R. afranicus n. sp. and R. turanicus sensu stricto together with high resolution images. Speciation is attributed to recent Sahara desert expansion that formed a natural barrier to dispersal approximately 5–7 million years ago. However, reproductive potential between these two species suggests that divergence time and mode of speciation were not sufficient for the development of reproductive isolation. We suggest speciation was complicated by divergence and population reintegration events driven by oscillating climatic conditions contributing to reticulate evolution and maintenance of compatibility between reproductive mechanisms. This study represents an integrative (iterative) approach to delimiting Rhipicephalus spp., and provides the first application of shape outlines for female spiracles and male adanal plates measured in a geometric morphometric framework, applied to testing species boundaries between ticks.Data for "Integrative Taxonomy and Species Delimitation of Rhipicephalus turanicus (Acari: Ixodida: Ixodidae)". Description: This work tests the species boundary between Afrotropical and Palearctic R. turanicus ticks. We show that molecular divergence and morphological differences are distinct and warrant separate species status. The dataset includes 1) alignments for 12S and 16S rDNA as well as the concatenated molecular dataset with MrBayes script, and 2) morphometric landmark data for male adanal plates and female spiracles as well as the photographs of these features. Available at https://data.mendeley.com/datasets/zjmtx7ghx4/1Supplementary Files: Figure S1. Operational definitions for landmarks.Figure S2. Fully labelled phylogenetic splits tree analysis of the 12S rDNA gene using TN+F+G4 nucleotide substitution model. Indicated are species and lineage names, GenBank accessions or study codes (reflected in Table S1), country of origin and neighbour network bootstrap support values. Bolded samples were used iteratively in morphometric analysis.Figure S3. Fully labelled phylogenetic splits tree analysis of the 16S rDNA gene using TPM3u+F+G4 nucleotide substitution model. Indicated are species and lineage names, GenBank accessions or study codes (reflected in Table S1), country of origin and neighbour network bootstrap support values. Bolded samples were used iteratively in morphometric analysis.Table S1. Material examined in this study.The Department of Science and Technology (DST), National Assets Budget allocated to the Gertrud Theiler Tick Museum, South Africa.http://www.elsevier.com/locate/ijpara2021-07-01hj2020Veterinary Tropical Disease