A new genus Proathyreacarus gen. nov. with the type species Athyreacarus staturosus is described. The genus Athyreacarus is divided into three subgenera: Athyreacarus sensu stricto, Athyreacaroides subgen nov. with the type species Athyreacarus brevisetosus, and Parathyreacarus subgen. nov. with the type species Athyreacarus magnificus. Four new species are described: Proathyreacarus argentiniensis sp. nov. from Argentina phoretic on the beetle Zefevazia rosascostai (Bolboceratidae); Athyreacarus (Athyreacaroides) australiensis sp. nov. and A. (Athyreacaroides) squamosus sp. nov. from Australia phoretic on the bolboceratid beetles Australobolbus pseudobscurius and Australobolbus rotundatus rotundatus, respectively; and Athyreacarus (Parathyreacarus) aequalis sp. nov. from Bolivia phoretic on the beetle Neoathyreus lobus (Bolboceratidae). The Athyreacaridae was described from Australia for the first time. A revised and updated key to genera, subgenera and species of Athyreacaridae is also provided.