Historically, for more than one and a half centuries, only one so-called “long-legged bat tick” species, i.e., Ixodes vespertilionis Koch was known to science. However, during the past decade, it was recognized on a molecular basis that long-legged ixodid ticks associated with bats may represent at least six species. Of these, until recently, five have been morphologically described. In this study, Ixodes ticks were collected from two Myotis species in southeastern Asia, Vietnam. Based on the morphological and molecular characteristics of the female, nymph and larva, Ixodes lanigeri Hornok, sp. nov. is described here. The male is unknown. Like other members of the Ixodes ariadnae complex, I. lanigeri Hornok apparently shows a preference for vesper bats as its typical hosts. In this context, host-association and geographical separation may explain the evolutionary divergence of I. lanigeri Hornok from its closest relative occurring on Murina hilgendorfi Peters in East Asia, Japan, because no Myotis or Murina spp. have overlapping distribution between Vietnam and the main islands of Japan. On the other hand, supposing that (similarly to I. ariadnae) I. lanigeri Hornok probably occurs on other myotine bats and knowing that several Myotis species indigenous in Vietnam have a broad geographical range in southern and southeastern Asia, the new tick species most likely has a widespread distribution in this area.

In Eurasia, the geographically most widespread ixodid tick species of the bat families Rhinolophidae Gray, Vespertilionidae Gray, and Miniopteridae Dobson were considered to belong to four species, Ixodes vespertilionis Koch, I. collaris Hornok, I. ariadnae Hor-nok, and I. simplex Neumann. Previous data attest that bat-associated tick species from Eastern Asia show remarkable genetic difference from the above four tick species, but in the absence of detailed morphological comparison these were regarded as conspe-cific. In this study we compensate for this lack of data on three bat-associated tick spe-cies, reporting their morphological comparison, as well as molecular and phylogenetic relationships. According to the results we describe the females of three tick species new to science, i.e., I. nipponrhinolophi Hornok & Takano, sp. nov., I. fuliginosus Hornok & Takano, sp. nov., and I. fujitai Hornok & Takano, sp. nov. In case of all three new tick species the cytochrome c oxidase subunit (coxI) gene showed remarkably high sequence differences from the species that they previously were thought to belong to, well exceed-ing the average limit delineating ixodid tick species. This, as well as observed morphological differences fully justify their taxonomical status as new species.