Tenuipalpidae (Acari: Trombidiformes) from Casuarinaceae (Fagales).

The Tenuipalpidae associated with the Casuarinaceae are reviewed, including one new genus, Palpipalpus gen. nov., twelve new species, and seven redescriptions. Two new generic records for Australia are established, Pentamerismus and Philippipalpus. The new species are: Chaudhripalpus costacola Beard and Seeman sp. nov., Crossipalpus gersoni Beard and Seeman sp. nov., Crossipalpus raveni Beard and Seeman sp. nov., Magdalenapalpus caperatus Beard and Seeman sp. nov., Magdalenapalpus forsteri Seeman and Beard sp. nov., Pentamerismus sititoris Beard and Seeman sp. nov., Pentamerismus hicklingorum Seeman and Beard sp. nov., Pentamerismus wardo Seeman and Beard sp. nov., Palpipalpus hesperius Beard and Seeman sp. nov. gen. nov., Philippipalpus flumaquercus Beard and Seeman sp. nov., Philippipalpus belah Beard and Seeman sp. nov., and Philippipalpus nigraquercus Seeman and Beard sp. nov.  Meyeraepalpus delfinadae Smiley et al., is reinstated based on new material and an analysis of its phylogenetic relationships. Crossipalpus muellerianae Smiley et al., Crossipalpus verticillatae Smiley et al., and Tegopalpus conicus Womersley are redescribed and rediagnosed from the original type specimens and newly collected material; and Chaudhripalpus creelae (Smiley et al.), Magdalenapalpus strandtmanni (Smiley et al.) and Philippipalpus agohoi Corpuz-Raros are redescribed and rediagnosed from type material only. All flat mite species were host-specific. Up to three species of flat mite were collected from a single she-oak species. Leg setation and ontogeny are reviewed for the taxa studied. A key to Tenuipalpidae from Casuarinaceae is provided. A phylogeny of the subfamily Tegopalpinae found the following relationships: Meyeraepalpus (Australopalpus, Crossipalpus, Palpipalpus (Magdalenapalpus (Philippipalpus (Chaudhripalpus + Tegopalpus)))). Our preliminary analysis of the Tegopalpinae suggested the group is monophyletic and its sister group is Phytoptipalpus.