A taxonomic review of the endemic Mexican genus Ceratotrupes Jekel, 1865 (Coleoptera: Geotrupidae: Ceratotrupini), with the description of an unexpected new species from the Sierra Madre del Sur

In this study, we revise the taxonomy of the endemic Mexican genus Ceratotrupes Jekel, 1865. It comprises three species, distributed in the Sierra Madre Occidental and Trans-Mexican Volcanic Belt (Ceratotrupes fronticornis (Erichson, 1847) and Ceratotrupes bolivari Halffter & Martínez, 1962), and the Sierra Madre del Sur (Ceratotrupes sturmi (Jekel, 1865)). We confirm C. mniszechi (Jekel, 1865) as a junior subjective synonym of C. sturmi. The examination of the holotype of C. sturmi and specimens recently collected in the Sierra Sur de Oaxaca (Oaxaca) and Omiltemi (Guerrero) allowed us to identify and describe a new species, Ceratotrupes gonzaloi sp. nov. from Omiltemi, Guerrero. We redescribe the morphology of C. sturmi and provide a diagnostic key to the four members of the genus Ceratotrupes. Photographs of the habitus and male genitalia of the four species, a distribution map, and observations on their ecology and biogeography are provided.