| abstract | The early history of the genus Tydeus, the type genus of the family Tydeidae, is complex and convoluted and, subsequently, even the identity of the type species of the family remains unclear. First, the literature is thoroughly analysed and morphological characters of some species are reappraised. After studying Oudemansʼ types, two species inquirendae, Tydeus croceus and T. cruciatus, are redescribed and a third, T. spathulatus, removed from synonymy and reinstated as a valid species. A fourth species, confused with T. spathulatus, is described. A lectotype is designated for T. spathulatus and a neotype for T. croceus. After discussion, the genus Lorryia Oudemans, 1925 is re-established in its pristine state. As the redescribed species were designated as type species by Oudemans, the following new generic synonymies are proposed: Raphitydeus Thor, 1933 and Lorryia Oudemans, 1925 sensu Kazmierski (1989, 1998) are junior synonyms of Brachytydeus Thor, 1931; Homeotydeus Andre, 1980 (partim) and Pseudolorryia Kazmierski, 1989 are junior synonyms of Calotydeus Oudemans, 1937; Brachytydeus Thor, 1933 (partim), Calotydeus Oudemans, 1937 (partim), Tydeus Koch, 1836 sensu Oudemans, 1937 (partim), Orthotydeus Andre, 1980, and Tydeus Koch, 1836 sensu Kazmierski, 1989 are junior synonyms of Tydeus Koch, 1836. To stabilize the usage of the names, especially that of the genus type of the family Tydeidae, the International Commission of Zoological Nomenclature will be asked to set aside all previous type species designations for Tydeus and to designate Tydeus spathulatus as the type species, with Oudemansʼ specimens from Italy as primary type material. |