Onthophagus hecate

Onthophagus hecate species group*. This group is diagnosed by the apical and internal male protibial margin projected (Figs. 1.39 –44); male protibial spur bent downwards (Figs. 1.39, 1.41 –44); male protibial apex with some short setae (Figs. 1.39 –44); male pronotum with a bifurcate projection bent downwards or level (Figs. 5.12 –13). A distinct O. hecate species group is recovered by the barcode and gene tree analyses (Figs. 1–2, 8–9) with a bootstrap value of 70 and is formed by O. hecate (Panzer), O. medorensis Brown, and O. orpheus (Panzer). This group is distributed in the eastern half of the United States of America and southeastern Canada. Several other species may pertain to this group. This species group and rodent nests have a strong but not exclusive relationship. The mtDNA barcode tree topology (Figs. 1–2, 6) suggests that O. hecate blatchleyi Brown should be elevated to species status. Brown (1925, 1927, 1929) initially suggested a relationship between O. cynomysi Brown, O. hecate, O. medorensis, and O. orpheus. Emlen et al. (2005) have shown prolific evolutionary lability in the horn gain and loss processes shown by Onthophagus worldwide. Emlen et al. (2005: fig. 4) estimated a Bayesian posterior probability of 100 for the O. orpheus – O. hecate tree clade. Emlen et al. (2005: fig. 5) proposed for the case of O. orpheus and O. hecate the loss of head horns, still showing rudimentary bumps at the base of the head, suggesting that full head horns may have been present in ancestral populations. At the same time, Emlen et al. (2005: fig. 7) proposed an independent gain event of pronotal horns for O. orpheus and O. hecate. These independent gain/loss processes seem to have confused previous taxonomists into considering the O. hecate species group as part of the O. mexicanus species group.