Birds are long-known as important disseminators of ixodid ticks, in which context mostly their latitudinal, south-to-north migration is considered. However, several bird species that occur in the eastern part of the northern Palaearctic are known to migrate westward. In this study, a female tick collected from the sedge warbler, Acrocephalus schoenobaenus, in Lithuania was identified morphologically and analyzed with molecular-phylogenetic methods. In addition, literature data were reviewed on ixodid tick species known to be associated with birds that have recorded east-to-west migratory route in the Palaearctic. The tick collected from A. schoenobaenus was morphologically identified as Ixodes apronophorus. Two mitochondrial genetic markers for this specimen showed 100% identity with a conspecific tick reported previously in Western Siberia, Russia. Based on literature data, as many as 82 bird species from 11 orders were found to have records of ringing in the easternmost part of the northern Palaearctic and recaptures in Europe. Of these bird species, 31 ixodid tick species were reported in the Euro-Siberian region. Nearly all passeriform bird species with east-to-west migration were reported to carry ticks, whereas no reports of tick infestation were documented from the majority of wetland-associated bird species, mostly from the orders Anseriformes and Charadriiformes. The first European sequences of bona fide I. apronophorus revealed genetic connectedness with conspecific ticks reported from Siberia. Since the principal hosts of this tick species are rodents which do not migrate large distances, the most likely explanation for genetic similarity in this direction is dispersal of this tick species via migratory birds. Given the high number of tick species that are known to associate with bird species migrating in westward direction, this appears to be an important means of the gene flow between geographically distant tick populations in the northern Palaearctic.

Background: The subgenus Pholeoixodes contains Ixodes species typically associated with birds that nest in cavities or with carnivorous mammals that are burrow-dwelling. Among ticks infesting the latter, Ixodes rugicollis is regarded as the rarest species in the western Palearctic. Despite the unique morphology of this species, its identification (especially of subadult stages) is difficult, and molecular-phylogenetic data to offer other diagnostic methods and a better understanding of its taxonomy are not available. Methods: In this study, a female and a male of I. rugicollis were collected in Romania. The female was compared morphologically to another female of this species collected in France and to the lectotype of Ixodes cornutus (from Tajikistan), which has similar morphology and host association. Following DNA extraction, two mitochondrial (cytochrome c oxidase subunit I: cox1 and the 16S rRNA gene) and two nuclear genetic markers (18S and 28S rRNA genes) of I. rugicollis were amplified and analyzed in a phylogenetic context. Results: Females of I. rugicollis and I. cornutus differed in the shape of their palps, scutum and areae porosae and the size of peritremes, but they were similar in palpal setal length, dental formula and arrangement of anal setae. Measurements of two I. rugicollis females examined were not less different from each other than from I. cornutus. Phylogenetically, I. rugicollis clustered with other members of its subgenus. The topology of all trees showed the position of bat-associated tick species of the subgenus Eschatocephalus among Pholeoixodes species. Conclusions: For the first time to our knowledge, this study provides high-resolution digital pictures of male and female I. rugicollis as well as corresponding molecular data. Morphological comparison of this species with I. cornutus could not resolve uncertainties in the validity of the latter species, which can only be accomplished after collecting new specimens of I. cornutus and consequent molecular comparisons. This study includes the first comprehensive molecular-phylogenetic analysis of western Palearctic Pholeoixodes species based on both nuclear and mitochondrial genetic markers and including I. rugicollis. The results of these confirm the phylogenetic position of subgenus Eschatocephalus within Pholeoixodes, justifying the need to merge them to comply with the taxonomic criterion of monophyly. Graphical Abstract: [Figure not available: see fulltext.]

Background: Among hard ticks (Acari: Ixodidae), the genus Ixodes comprises the highest number of species, which in turn are most numerous in the Afrotropical zoogeographic region. In South Africa extensive morphological studies have been performed on Ixodes species but only few reports included molecular analyses. Methods: In this study, 58 Ixodes spp. ticks, collected from ten mammalian and eight avian host species in South Africa, were molecularly and phylogenetically analyzed. In addition, a newly collected sample of the Palearctic Ixodes trianguliceps was included in the analyses. Results: Among the ticks from South Africa, 11 species were identified morphologically. The majority of ticks from mammals represented the Ixodes pilosus group with two species (n = 20), followed by ticks resembling Ixodes rubicundus (n = 18) and Ixodes alluaudi (n = 3). In addition, single specimens of Ixodes rhabdomysae, Ixodes ugandanus, Ixodes nairobiensis and Ixodes simplex were also found. Considering bird-infesting ticks, Ixodes theilerae (n = 7), Ixodes uriae (n = 4) and ticks most similar to Ixodes daveyi (provisionally named I. cf. daveyi, n = 2) were identified. Molecular analyses confirmed two species in the I. pilosus group and a new species (I. cf. rubicundus) closely related to I. rubicundus sensu stricto. Phylogenetic trees based on concatenated mitochondrial or mitochondrial and nuclear gene sequences indicated that the subgenus Afrixodes forms a monophyletic clade with bird-associated exophilic ticks (subgenus Trichotoixodes). Ixodes trianguliceps clustered separately whereas I. alluaudi with their morphologically assigned subgenus, Exopalpiger. Conclusions: Phylogenetic analyses shed new lights on the relationships of Ixodes subgenera when including multiple sequences from subgenus Afrixodes and African as well as Palearctic species of subgenera Trichotoixodes and Exopalpiger. Subgenera Afrixodes and bird-associated Trichotoixodes share common ancestry, suggesting that the latter might have also originated in Africa. Regarding the subgenus Exopalpiger, I. alluaudi is properly assigned as it clusters among different Australian Ixodes, whereas I. trianguliceps should be excluded. Graphical Abstract: [Figure not available: see fulltext.].