| abstract | Ornithodoros tabajara n. sp. is described from laboratory-reared larvae and adult specimens collected in the Brazilian Caatinga. This new species shares the ecological niche with Ornithodoros rietcorreai and is likely associated with colonial rodents of genus Kerodon. However, O. tabajara n. sp. is morphologically easy to distinguish from O. rietcorreai and other Neotropical Ornithodoros by a unique combination of characters: larva with 17 pairs of dorsal setae (seven anterolateral, three central and seven posterolateral), sub-oval dorsal plate, hypostome blunt apically with dentition formula 2/2 along its extension, only one pair of posthypostomal setae, six pairs of sternal setae, posteromedian setae absent, and leave-shaped anal valves; alive adults with whitish islands of mammillae symmetrically distributed on dorsum (not visible in ethanol-preserved specimens), and median disk merging with posteromedian file. A phylogenetic analysis performed with mitochondrial 16S rDNA sequences points O. tabajara n. sp. as O. rietcorreaiʼs sister taxon, which rises the hypothesis of sympatric speciation. |