Onthophagus eulophus Bates 1887

Onthophagus eulophus species group*. This group is diagnosed by a slightly emarginate clypeus; apical and internal male protibial margins projected (Figs. 1.23 –25); male protibial apex with some short setae (Figs. 1.23 –25); male protibial spur strongly bent inwards (Figs. 1.23 –25); male pronotum with a horn or a plate-like horn, which is level or turned upwards, never bent downwards. Although no species of this group could be included in the mtDNA analysis, this aggregation is established based on a characteristic set of morphological characters, like having apical and internal male protibial margins projected and a male protibial spur strongly bent inwards (Figs. 1.23 –25). Moreover, contrary to the O. mexicanus species group that have long and slender male protibiae (Figs. 1.26 –28), this group has short and stout male protibiae (Figs. 1.23 –25). All species of this group seem to be associated with rodent nests; this behavior is supported by the shortened male protibiae and bent male protibial spurs (Moctezuma & Halffter 2021; Moctezuma et al. 2023). We consider that this group includes eight species (Table 7). Zunino & Halffter (1997) and Moctezuma & Halffter (2021) consider these species part of the O. mexicanus species group. The O. eulophus species group is primarily distributed in the mountains of the southwestern United States of America and along the Mexican Pacific mountain slopes, except for O. totonacus Moctezuma & Halffter, which lives along the Mexican Gulf piedmont.