The three most common Ixodes spp. ticks found on songbirds in Western Europe are Ixodes
frontalis, I. arboricola and I. ricinus. As the latter species is a generalist, it shares several
avian hosts with the two strictly ornithophilic species. Infestations of the three species can
overlap in time and space, implying that tick-borne pathogens maintained by the ornithophilic
ticks and their hosts could be bridged by I. ricinus to non-avian hosts. Whereas the
endophilic Ixodes arboricola only occurs in cavities, I. frontalis has been collected frequently
by flagging methods from understory vegetation, which is also the habitat of the fielddwelling
I. ricinus. As the latter two species have rather similar morphological
characteristics, they can easily be confused with each other. In this study, we present
scanning electron photomicrographs of all developmental stages of I. arboricola and I.
frontalis, and provide a differential diagnosis key to distinguish the ornithophilic ticks from I.
ricinus. In addition, we interpreted their phylogenetic associations based on mitochondrial
16S rDNA with other Ixodes spp. ticks (I. lividus, I. turdus, I. brunneus, I. vespertilionis, I.
trianguliceps, I. hexagonus, I. scapularis).