Onthophagus acerus Gillet, 1930

(Figs. 1, 13, 25–29)

Type material. Holotype male (IRSNB), from [Papua New Guinea:] “Brit. N. \ Guinea ”.

Diagnosis. Clypeal border of this species evenly rounded, with a narrowly reflexed margin; behind this margin surface crowdedly punctate, with very vague median protrusion. Frons and pronotum without any distinct elevations. Dorsum generally distinctly, finely punctate, punctation sparse on disc, but not with micropunctation only. Puncture impressions of elytral striae fine, not enlarged distally. Eye foramina large, closed behind, i.e., very narrow posterior end of gena reaching occipital side; interocular distance approximately 2 eye widths (contra Balthasar 1969). Genal border rounded. Generally dark-brown, shiny. Abdominal ventrites with row of coarse ocellate punctures along base. Small, body length approximately 6 mm. The holotype is the only specimen known.