Language: Spanish with bilingual keys and summary in English and Spanish
This monograph presents a taxonomic, phylogenetic, ecologic and biogeographic study of an American group of Coleoptera belonging to the genus Onthophagus (Scarabaeidae), the "chevrolati group". The extra-American relationships of the New World Onthophagus fauna are discussed for the first time, as well as their general systematics; the relationships of the group are treated in depth from both phyletic and geographical points of view. The group is formed by 39 taxa (30 species, plus 8 non-nominotypical subspecies), of which 19 are described for the first time. The information on each species includes the reference of the original description, type locality, type material (almost always examined), a detailed description of the adult (with schematic figures), figures of male and female genitalia, a record of examined material, comments on affinities, and notes on distribution, ecology and biology. Dichotomic keys, in both Spanish and English, are also provided. In the biogeographical and evolutionary part of the monograph, it is emphasized that the chevrolati group is an exceptional example of the complexity and variety of the distributions associated with the mountains of the Mexican Transition Zone, and of their evolutionary history. The geological and climatic history of the Zone is summarized and then the taxa distributions are analyzed in terms of Distribution Patterns. The different phyletic lineages follow different Distribution Patterns, according to the allocrony of their formation processes. A single primitive lineage corresponds to the more ancient Paleoamerican Pattern whereas the remaining elements correspond in general to a modern pattern: the Neartic one, with the exception of one phyletic branch, following the Mesoamerican Mountain Pattern, without sharing the old South American origin with the majority of the members of the Pattern.