 Representative examples are presented, but many more species are not mentioned here.A comprehensive 2019 study found subgenera "Orobatus" and "Anoplobatus" to be monophyletic, while all other subgenera to be paraphyletic or polyphyletic.The genus has a likely North American origin, with the oldest fossils known from the Eocene, and expansion into Eurasia and elsewhere during the Miocene.