I uncoverd this mating pair in a rotting log. I photographed the pair adjacent to a scale--not shown. I believe the female is the smaller, slightly trimmer, individual on the left (about 30 mm) and the male is the more robust individual on the right (about 35 mm). Other photos show the heads. The presumed female has a thinner horn than the presumed male. (I've uncovered other what I thought were pairs of these before, just not while they were mating. I've seen similar subtle differences in morphology.)