Onthophagus hircus Billberg 1815

Onthophagus hircus species group. This group is diagnosed by a male protibial apex with some short setae (Figs. 1.8 –15); apical and internal margin of male protibia obtuse or with obsolete tooth (Figs. 1.8 –15) (O. confusus has long male protibiae with internoapical tooth distinct and acuminated); male protibial spur downward bent at the apex (Figs. 1.8 –15); pronotum without horns; metafemur very short and stout (Figs. 2.8 –15); apex of parameres poorly developed and defined. Zunino & Halffter (1997) established an O. hirculus species group, later renamed O. hircus by Rossini et al. (2018a). Although Zunino & Halffter (1997) do not mention it, this group is based on and corresponds to the “5 e Groupe” of Boucomont (1932), to which they erroneously incorporated O. crinitus. In the Rossini et al. (2018a, 2018b) study of the O. hircus species group, the authors established five species complexes: O. curvicornis, O. hircus, O. ophion, O. osculatii, and O. rubrescens. The present analysis recovers an O. hircus species group formed by species of the O. hircus, O. osculatii, and O. rubrescens species complexes. The O. curvicornis species complex is elevated to a group level in this study, as suggested by the present mtDNA analyses. No members of the O. ophion species complex could be analyzed. The present analysis needs to contain a significant enough sample of analyzed species to validate all the proposed O. hircus species complexes. This group presents a distribution from Mexico to the peripheral Amazonian basin of South America, including the Lesser Antilles. Interestingly, Emlen et al. (2005: fig. 4) recovered an O. hircus – O. nasutus clade in their phylogenetic analysis, thus suggesting a relationship between the two species groups. The present barcoding analysis (Figs. 1–2) recovers the same relationship, whereas the bootstrap (Fig. 8) and the partition (Fig. 9) analyses suggest the O. nasutus species group as a sister group to the O. clypeatus – O. dicranius species groups. A more comprehensive analysis is needed. Breeschoten et al. (2016) register an O. hircus species group with a bootstrap value of 61 with an estimated crown age of approx. 10.5 Mya and a stem age of approximately 14 Mya. Schwery & O'Meara (2021) recovered also an O. hircus species group with a bootstrap support of 74. Moctezuma et al. (2024) proposed a stem value of around 17.5 Mya for the species group and a crown value of around 11 Mya.