Sorry about that, Woods Reserve disagrees with absolutely everything else. Definitely Cotter Dam picnic area at the upper end. I have another shot of a Hemigomphus male taken about 1 minute later (with two Arrowhead Rockmaster shots intervening), so probably same individual, nearly 40 deg from rear on but equally fuzzy on the front end. In that view I see a bulge in the SAAs towards the middle, suggests H. heteroclytus to me. I'll post it.