BACKGROUND: In a recent study on ixodid bat ticks from Eurasia, a high genetic 
difference was found between Ixodes vespertilionis from Europe and Vietnam. 
Accordingly, it was proposed that I. vespertilionis is a species complex, with 
at least one additional, hitherto undescribed species. The aim of the present 
study was to investigate the morphology of bat ticks from Vietnam and to assess 
their taxonomic status in comparison with those collected in Europe.
FINDINGS: Ixodid bat ticks (two females and two nymphs) collected from the 
pomona leaf-nosed bat (Hipposideros pomona) (Hipposideridae) and intermediate 
horseshoe bat (Rhinolophus affinis) (Rhinolophidae) in Vietnam showed major 
morphological differences from European isolates of I. vespertilionis, including 
the shape of the scutum, the enclosure and shape of porose areas, the presence 
of a caudo-lateral collar-like ridge ventrally on the basis capituli, polytrich 
coxae with short setae, and grouped (non-linear) arrangement of anterior pit 
sensillae in Haller's organ.
CONCLUSIONS: In this study the female and the nymph of an ixodid bat tick 
species from Vietnam are described for the first time. The genetic and 
morphological differences between I. vespertilionis Koch, 1844 and these bat 
ticks from Vietnam justify the status of the latter as a distinct species, 
Ixodes collaris Hornok n. sp.