American mitogenome reference for the tropical brown dog tick, Rhipicephalus linnaei (Audouin, 1826)

Abstract

The brown dog tick, Rhipicephalus linnaei (Audouin, 1826), is distributed across the American continent and is formerly known as the "tropical lineage". It belongs to the Rhipicephalus sanguineus (Latreille, 1806) species complex, referred to as R. sanguineus (sensu lato). Mitochondrial genome sequences are frequently used for the identification and represent reference material for field studies. In the present study, the entire mitochondrial genomes of R. linnaei (∼15 kb) collected from dogs in Mexico were sequenced and compared with available mitogenomes of R. sanguineus (s.l.). The mitochondrial genome is ∼90% identical to the reference genome of R. sanguineus (sensu stricto, former "temperate lineage") and > 99% identical to R. linnaei mitogenome derived from the neotype. Two additional mitogenomes were obtained and described as R. linnaei and R. turanicus from dogs in Saudi Arabia. The present study delivers a molecular reference for R. linnaei from America and complements R. linnaei mitogenomes from Africa, Asia and Australia. We propose to consider the complete mitogenome, as the reference for American R. linnaei, even when partial mitochondrial cox1, 12S rRNA or 16S rRNA genes are characterised.

Keywords: Brown dog tick; Genome; Next-generation sequencing; Phylogeny; Rhipicephalus sanguineus complex; mtDNA.

Graphical abstract

Fig. 1

Phylogenetic relationships of Rhipicephalus sanguineus (sensu lato) based on complete mitogenomes. A Complete 30 mitogenomes of R. sanguineus (s.l.) were aligned and the tree was inferred from nucleotide data; there were a total of 15,029 positions in the final dataset. The optimal tree shown was inferred using the Minimum Evolution (ME) method. The tree was drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Maximum Composite Likelihood method and are in the units of the number of base substitutions per site. For the ME tree, all ambiguous positions were removed for each sequence pair (pairwise deletion option). The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates for ME/100 replicates for ML [maximum likelihood]) are shown next to the branches. The species from which the mitogenome belongs to is indicated on the right and colour coded. B Complete 18 mitogenomes of R. linnaei were aligned together with two R. camicasi mitogenomes as outgroup. The tree was inferred from nucleotide data, there were a total of 14,755 positions in the final dataset. The optimal tree shown was inferred using the Minimum Evolution (ME) method. The tree was inferred as described above. Each mitogenome is identified by its GenBank accession number and voucher identifier together with the country where it was collected. The new mitogenomes from this study are shaded.

Fig. 2

World map distribution of Rhipicephalus sanguineus (sensu lato) based on complete mitogenomes. Each mitogenome is colour coded (as in Fig. 1) based on species identification, each circle represents one mitogenome. Reference sequences for R. linnaei are now available from the Americas, Africa, Asia and Australia.