Department of Parasitology and Zoology, University of Veterinary Medicine, Budapest, Hungary.
HUN-REN-UVMB Climate Change: New Blood-Sucking Parasites and Vector-Borne Pathogens Research Group, Budapest, Hungary.
Parasit Vectors. 2023 Oct 28;16(1):392. doi: 10.1186/s13071-023-05998-5.
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.
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.
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.
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.
在硬蜱（蜱螨目：硬蜱科）中，Ixodes 属包含的物种数量最多，而这些物种在非洲动物地理区系中最为丰富。在南非，已经对 Ixodes 物种进行了广泛的形态学研究，但只有少数报告包括分子分析。
在这项研究中，从南非的十种哺乳动物和八种鸟类宿主中采集了 58 种 Ixodes 属蜱虫，对其进行了分子和系统发育分析。此外，还包括了新采集的来自古北界的 Ixodes trianguliceps 样本。
在南非采集的蜱虫中，11 种通过形态学鉴定。来自哺乳动物的大多数蜱虫属于 Ixodes pilosus 组，其中两种（n=20），其次是类似于 Ixodes rubicundus（n=18）和 Ixodes alluaudi（n=3）的蜱虫。此外，还发现了单个 Ixodes rhabdomysae、Ixodes ugandanus、Ixodes nairobiensis 和 Ixodes simplex 的标本。考虑到寄生鸟类的蜱虫，鉴定出 Ixodes theilerae（n=7）、Ixodes uriae（n=4）和最类似于 Ixodes daveyi（暂命名为 I. cf. daveyi，n=2）的蜱虫。分子分析证实 I. pilosus 组中有两个种，以及一个与 I. rubicundus 密切相关的新种（Ixodes cf. rubicundus）。基于线粒体或线粒体和核基因序列的系统发育树表明，亚属 Afrixodes 与鸟类相关的外生性蜱虫（亚属 Trichotoixodes）形成单系群。Ixodes trianguliceps 聚类分离，而 I. alluaudi 与其形态学上分配的亚属 Exopalpiger 聚类分离。
当包括来自亚属 Afrixodes 的多个序列以及来自亚属 Trichotoixodes 和 Exopalpiger 的非洲和古北界物种的序列时，系统发育分析为 Ixodes 亚属的关系提供了新的认识。亚属 Afrixodes 和与鸟类相关的 Trichotoixodes 具有共同的祖先，这表明后者可能也起源于非洲。关于亚属 Exopalpiger，I. alluaudi 的归属是正确的，因为它与不同的澳大利亚 Ixodes 聚类，而 I. trianguliceps 应该被排除。
