Department of Parasitology and Zoology, University of Veterinary Medicine, Budapest, Hungary.
Thuringian State Office for Consumer Protection (TLV), Bad Langensalza, Germany.
Ticks Tick Borne Dis. 2021 Jul;12(4):101715. doi: 10.1016/j.ttbdis.2021.101715. Epub 2021 Mar 23.
Three Palearctic members of the subgenus Pholeoixodes, i.e., Ixodes canisuga, Ixodes hexagonus and Ixodes kaiseri are frequently collected from dogs, cats, red foxes, badgers and other carnivorous/insectivorous hosts in Europe. While a pictorial identification key has been reported for female Pholeoixodes ticks, a similar work has not been done on their male, nymphal and larval specimens. This study was initiated in order to clarify and re-examine those morphological characters of these three tick species, which can be used relatively easily to identify/distinguish them. In the case of larvae the aims included finding alternatives to chaetotaxy, which is difficult to observe and its usefulness is also affected by uncertainties in literature data. For this, 609 Pholeoixodes ticks (males, nymphs and larvae) were collected from carnivores, hedgehogs and their environment in six European countries (representing Western, Central and Southeastern Europe), followed by detailed morphological examination and/or molecular analyses to confirm the identity of their species. Based on the morphology of 84 molecularly analyzed specimens and a new identification key compiled accordingly, altogether 116 I. canisuga, 277 I. hexagonus and 216 I. kaiseri males, nymphs and larvae were identified. Ixodes kaiseri was not found in Western Europe, where I. canisuga predominated. In Central Europe, all three Pholeoixodes species were collected, the largest number of specimens represented by I. hexagonus. On the other hand, in Southeastern Europe I. kaiseri had the highest abundance. In conclusion, the morphology of internal spur on the first coxae (as the traditionally used character to distinguish I. hexagonus from other Pholeoixodes species) is trustworthy to recognize males but is less informative in the case of nymphs and larvae. The latter can be identified more properly by observing the morphology of basis capituli. In particular, nymphs and larvae of I. canisuga have anteriorly flattened basis capituli, forming a plateau that surrounds the base of the hypostome. On the other hand, nymphs and larvae of I. hexagonus and I. kaiseri lack a similar plateau, but (unlike I. canisuga) have cornuae, which are either posterolaterally or caudally directed, respectively.
在欧洲，犬首属（Pholeoixodes）的三个近北极物种，即犬栉首蚤（Ixodes canisuga）、六棘血蜱（Ixodes hexagonus）和哈萨克血蜱（Ixodes kaiseri），常从犬、猫、赤狐、獾和其他食肉/食虫宿主身上采集。虽然已经有关于雌性犬首属蜱的图谱识别关键特征，但对其雄性、若虫和幼虫的标本尚未进行类似的研究。本研究旨在阐明和重新检查这三个蜱种的形态特征，这些特征可以相对容易地用于识别/区分它们。对于幼虫，目标包括寻找比刚毛形态学更具替代性的特征，因为刚毛形态学难以观察，其有用性也受到文献数据不确定性的影响。为此，从欧洲六个国家的食肉动物、刺猬及其环境中采集了 609 只犬首属蜱（雄性、若虫和幼虫），随后进行了详细的形态学检查和/或分子分析，以确认其物种身份。根据 84 只经分子分析的标本的形态特征和据此编制的新鉴定关键特征，总共鉴定了 116 只 I. canisuga、277 只 I. hexagonus 和 216 只 I. kaiseri 雄性、若虫和幼虫。在西欧没有发现 I. kaiseri，而 I. canisuga 则占主导地位。在中欧，三种犬首属蜱都有采集，其中以 I. hexagonus 的标本数量最多。另一方面，在东南欧，I. kaiseri 的丰度最高。总之，第一对步足上内部距的形态（作为传统上用于区分 I. hexagonus 和其他犬首属物种的特征）可用于识别雄性，但在若虫和幼虫的情况下信息量较少。后者可以通过观察头胸部基部的形态来更准确地识别。特别是，I. canisuga 的若虫和幼虫的头胸部基部向前扁平，形成一个环绕口下板基部的高原。另一方面，I. hexagonus 和 I. kaiseri 的若虫和幼虫缺乏类似的高原，但（与 I. canisuga 不同）具有分别指向后外侧或尾侧的角突。
