Based on the type materials deposited in the Trouessart collection (Museum national d'Histoire naturelle, Paris, France), the six formerly known species of the feather mite genus Protolichus Megnin et Trouessart, 1884 (Pterolichidae: Pterolichinae) are redescribed: Protolichus brachiatus Trouessart, 1884, P. magnificus Favette et Trouessart, 1904, P. strangulatus Favette et Trouessart, 1904 (brachiatus group), P. casuarius Trouessart, 1884, P. crassior Trouessart, 1884, and P. gratus Favette et Trouessart, 1904 (crassior group). One new species of the brachiatus group found in the examined materials is described: Protolichus sigillator sp. n. from Chalcopsitta scintillata chloroptera (Salvadori, 1876) (Psittacidae: Loriinae). A new expanded diagnosis for the genus Protolichus is provided and a key to all known species is constructed for the first time. Known host associations of Protolichus species with parrots of the Old World are critically revised. Mites of this genus are apparently restricted to lories and lorikeets (Loriinae) distributed in the Australian and Indo Malayan regions, particularly to representatives of the genera Chalcopsitta, Charmosyna, Lorius, Pseudeos, and Trichoglossus, while other formerly recorded hosts, including those from other subfamilies of parrots, seem to be results of accidental contaminations.