Abstract
BackgroundThe taxonomic status of the brown dog tick (Rhipicephalus sanguineus sensu stricto), which has long been regarded as the most widespread tick worldwide and a vector of many pathogens to dogs and humans, is currently under dispute.MethodsWe conducted a comprehensive morphological and genetic study of 278 representative specimens, which belonged to different species (i.e., Rhipicephalus bursa, R. guilhoni, R. microplus, R. muhsamae, R. pusillus, R. sanguineus sensu lato, and R. turanicus) collected from Europe, Asia, Americas, and Oceania. After detailed morphological examination, ticks were molecularly processed for the analysis of partial mitochondrial (16S rDNA, 12S rDNA, and cox1) gene sequences.ResultsIn addition to R. sanguineus s.l. and R. turanicus, three different operational taxonomic units (namely, R. sp. I, R. sp. II, and R. sp. III) were found on dogs. These operational taxonomical units were morphologically and genetically different from R. sanguineus s.l. and R. turanicus. Ticks identified as R. sanguineus s.l., which corresponds to the so-called “tropical species” (=northern lineage), were found in all continents and genetically it represents a sister group of R. guilhoni. R. turanicus was found on a wide range of hosts in Italy and also on dogs in Greece.ConclusionsThe tropical species and the temperate species (=southern lineage) are paraphyletic groups. The occurrence of R. turanicus in the Mediterranean region is confirmed. A consensual re-description of R. sanguineus s.s. and R. turanicus will be necessary to solve the taxonomic problems within the so-called R. sanguineus group.
Highlights
The taxonomic status of the brown dog tick (Rhipicephalus sanguineus sensu stricto), which has long been regarded as the most widespread tick worldwide and a vector of many pathogens to dogs and humans, is currently under dispute
I to IV) presenting morphological characters differing from known species and from those above were found in Italy, Greece, Spain, Portugal, India, Pakistan and Nigeria. These operational taxonomic units (OTUs) were closely related to R. turanicus and/or R. sanguineus s.l., albeit the punctuation pattern on dorsal scutum, shape of spiracular plates, adanal plates and accessory shields were distinct
Intraspecific morphological variations among ticks identified as R. sanguineus s.l. and R. turanicus were evident, mainly in terms of colour, size, scutal punctuation pattern, female genital opening shape, spiracular plate shape length, male adanal plate shape and male caudal process
Summary
Tick collection and identification The majority of the ticks included in this study were selected from >5,000 specimens examined during previous investigations carried out from 2008 to 2012 in Brazil, Italy, Portugal, Spain, and Greece [29,30,31,32]. Morphological study Out of >5,000 ticks examined, 278 representative specimens of each species were selected and morphologically studied in further detail (Table 1). The ratio between the width dorsal tail of spiracular plates, and the width of the adjacent festoon (ST/F1 ratio) was calculated, as well as the ratio between the length and the width (at base) of male adanal plates These characters are considered taxonomically relevant for Rhipicephalus spp. differentiation (e.g., [14,16,17]). Genetic study After a detailed morphological study, 197 representative tick specimens were selected for genetic analysis (for details on the number of ticks for each species, see Table 1). Data comparisons were made considering the tick species for which more than 10 specimens were measured, while others The nucleotide sequences reported in this article have been deposited in the GenBank database (12S rDNA: KC243 786-KC243834, KF145151; 16S rDNA: KC243835-KC24 3871, KF145150; cox: KC243872-KC243931, KF145152, KF145153)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
