AbstractThe systematic status of the genus Tarsocheylus Berlese, 1904 and the position of the family Tarsocheylidae Atyeo and Baker, 1964 in the Prostigmata is reviewed. The family does not belong in either the Raphignathoidea or the Anystoidea but in its own superfamily, the Tarsocheyloidea, which is described for this purpose. In turn, this superfamily is placed alongside the Heterocheyloidea in the Heterostigmata.Because the type-species of Tarsocheylus, T. paradoxus Berlese, 1904, is conspecific with Hoplocheylus discalis Atyeo and Baker, 1964 (new synonymy), the concept of Hoplocheylus Atyeo and Baker, 1964, which has remained until now as originally proposed, is the same as that of Tarsocheylus. However, a new case is made for recognizing these genera as mutually distinct, based on other morphological criteria. Tarsocheylus atomarius Berlese, 1913, the type-species of Hoplocheylus, is apparently conspecific with Hoplocheylus canadensis Marshall, 1966 (new synonymy) and perhaps with one or two other described species from North America. A third generic entity, represented by Hoplocheylus johnstoni Atyeo and Baker, 1964, is noted but not named or formally described. Hoplocheylus pickardi Smiley and Moser, 1968 is conspecific with H. similis Delfinado and Baker, 1974 (new synonymy).Hemitarsocheylus Soliman and Zaher, 1975, which was described as a new genus in the Tarsocheylidae, is congeneric with Stigmocheylus Berlese, 1910 (new synonymy). This genus does not belong in the Tarsocheyloidea, but rather in the Anystoidea.A list of character states found useful in recognizing groupings of species of Tarsocheylidae is presented. Based on the collection data with specimens representing described and undescribed species at hand, the known distribution of the Tarsocheylidae is extended to include Australia and western North America, and the second known instance of an association with passalid beetles is recorded.From a phylogenetic standpoint, the Tarsocheyloidea and Heterocheyloidea are proposed as sister groups that together constitute a new suprafamilial taxon, the Tarsocheylina. In turn, the Tarsocheylina and Tarsonemina are proposed as sister groups, and both are described; together, they form the Heterostigmata.The systematic and phylogenetic relationships of the Heterostigmata (including the Tarsonemina) to the Prostigmata and the Astigmata are reviewed. Not only should the Heterostigmata be retained in the Prostigmata but it should be lowered in hierarchic rank, such that it is a part of the Eleutherengona. The stock that gave rise to the Anystoidea and related superfamilies is shown to be ancestral to the Heterostigmata as well.
