The culprit is the model organism, Onthophagus nigriventris. Although most of us will know it as a dung beetle. So Sarda was right, if vague. John Orcutt's brave descent of the Linnean hierarchy went unrewarded, but John Hopkin came closest - even going so far as to provide the correct genus. I, however, was spot on.
Well done me.
You might like to know that the striking horns in the original photo are just one of a variety of phenotypic expressions in this species (see photo below).