Historically, for more than one and a half centuries, only one so-called "long-legged bat tick" species, i.e., Ixodesvespertilionis 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, Ixodeslanigeri Hornok, sp. nov. is described here. The male is unknown. Like other members of the Ixodesariadnae 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 Murinahilgendorfi 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.