A genus of argasid ticks similar to Ornithodoros but characterized by a granulated integument, a hypostome that is vestigial in the adult but well developed in the spiny nymphs, and the absence of eyes and hood. Two species are recognized: Otobius lagophilus (the face tick of rabbits) and Otobius megnini, the spinose ear tick that causes otobiosis in horses, cattle, sheep, dogs, and some wild animals; it occurs in southwestern parts of the U.S., where it is an important pest, and is also distributed worldwide.