Genus Perithous Holmgren, 1859

Type species: Ephialtes albicinctus Gravenhorst, 1829 .

Synonym: Hybomischos Baltazar, 1961 .

Perithous is a Holarctic and Oriental genus comprising 18 described species, ten of them occur in the Palaearctic region (Yu et al. 2016). Three species were recorded from the Nearctic region, but only P. scurra (Panzer) is native while the other two, P. divinator (Rossi) and P. septemcinctorius (Thunberg), were introduced from Europe (Townes & Townes 1960: 209; Torgersen 1972). One undescribed species of Perithous is found in the State of Nuevo León in northeast Mexico. This is the first record of the genus from Mexico and the southernmost finding of Perithous in the New World.

Species of Perithous are known as parasitoids in nests of wasps (mainly Crabronidae and Sphecidae) in canes and twigs (Townes & Townes 1960; Carlson 1979; Kasparyan & Khalaim 2007).