Identification key to the species of the genus Ceratotrupes Jekel, 1865

1. Anterior half of lateral edges of pronotum curved ........................................................................... 2

– Anterior half of lateral edges of pronotum straight and convergent ................................................. 3

2. Anterior angles of pronotum of male evenly curved; outer surface of the first antennomere of antennal club with a deep elliptical groove (Fig. 2C); middle and posterior trochanters densely and clearly punctate ....................................................................... C. bolivari Halffter & Martínez, 1962

– Anterior angles of pronotum of male obtusely squared; outer surface of the first antennomer of antennal club either without or with a feeble groove; middle and posterior trochanters with scattered punctures ......................................................................................... C. fronticornis (Erichson, 1847)

3. Posteromedial edge of pronotum without margin (Fig. 4C); clypeal horn strong, as large as one third the distance between inner margin of eyes, tip medially depressed (Fig. 4A, C); anteromedial pronotal projection with parallel sides (Fig. 4A, D), apically almost as large as half the distance between inner margin of eyes, apical edge widely depressed, with lateral protrusions distant; elytral interstriae very finely and densely punctate ........................................................ C. gonzaloi sp. nov.

– Posteromedial edge of pronotum margined (Fig. 3C); clypeal horn thin, as large as one fifth of the distance between inner margin of eyes, tip medially not depressed, narrow and blunt (Fig. 3A, C); anteromedial pronotal projection with convergent sides, apically almost as large as one third of the distance between inner margin of eyes, apical edge very narrowly depressed, with lateral protrusions very close; elytral interstriae unpunctured ................................... C. sturmi (Jekel 1865)