The South American tribe Nycteliini (Pimeliinae) comprises nine genera distributed from central Peru to southern Argentina and Chile: Gyriosomus Guérin-Méneville, Pilobalia Burmeister, Entomoderes Solier, Nyctelia Latreille, Epipedonota Solier, Psectrascelis Solier, Scelidospecta Kulzer, Auladera Solier, and Mitragenius Solier. A cladistic analysis of the genera of Nycteliini is conducted, including 93 characters and 11 terminal taxa because two of the genera are treated as two terminal units: Epipedonota and Mitragenius. The one most parsimonious cladogram obtained shows that Nycteliini is a monophyletic group characterized by two synapomorphies from internal morphology and female genitalia. The generic relationships are resolved and the genus Mitragenius appears as non-monophyletic. The results suggest that the species of Nycteliini should be arranged best in 11 genera. The study confirms the importance of the use of new characters, such as genital structures and internal morphology in the classification of Tenebrionidae. The paper includes a discussion of the phylogeny of the tribe and information on evolution of thoracic endosternites was used along the tree to analyze evolutionary patterns.