Lusius Tosquinet, 1903: 384. Type species: Lusius macilentus Tosquinet, 1903, by monotypy. Mesochorischnus Heinrich, 1938: 128. Type species: Mesochorischnus tenuissimus Heinrich, 1938, by original designation and monotypy. Synonymized by Townes & Townes (1966: 217).
The unidentate and falcate mandibles set Lusius Tosquinet, 1903 apart from all the other genera of Phaeogenini, except for Heterischnus Wesmael, 1859, from which it can be distinguished by the absence of vein 3rs-m (areolet open) in the fore wing and abscissa of CU in the hind wing. Additionally, the genus can be separated from other genera by the following combination of characters: (1) head hemispherical; (2) basal flagellar segments slender and long; (3) vertex long and slightly convex behind ocelli; (4) occipital and hypostomal carinae joining at mandibular base; (5) notaulus complete, ending posteriorly in a median depression; (6) gastrocoeli long with thyridia faint; (7) ovipositor extending beyond apex of metasoma; (8) male genitalia with gonoforceps reduced to rod-like processes (Baltazar 1964; Diller 2006; Rousse et al. 2013).
The genus has a tropical distribution, and it occurs in the Afrotropical, Indomalayan and Neotropical regions. In Africa, Lusius is represented only by two species: L. flummox Rousse & van Noort, 2013, and L. tenuissimus Heinrich, 1938 (Table 1).