I had this specimen as a P. tristis until recently. I decided it fit better P. adoxus as the posterior lateral setae of the pronotum are placed noticeably forwards than on any specimens of P. tristis I have. The base of the pronotum also has wrinkles across the middle. Also slightly larger than P. tristis I have collected in Indiana.

does indeed appear (photographically) forward enough of hind angles to be P. adoxus. I wish the hind angles were a bit more obtuse typical of that species. The clincher (not well known) is counting the linear arrangement of setae on the broad front face of the mesofemur near its lower border (ignore the seta on the proximal mesotrochanter). P. adoxus almost constantly has three such setae on each mesofemur and most P. tristis have sets of 2 such seta, some with 2 + 3 setae. Brad, let me know what you find here.

Examining the mesofemurs, one has 3 setae and other 2.

might help. For example, if every typical "P. tristis" in same general area fits 2 + 2, then departure 2 + 3 likely supports "P. adoxus" here which already has external traits in its favor.

I have one P. tristis collected from the same site/date. It is 2+2. Its external morphology (location of basal setae, etc.) is typical tristis. (General collection area is fairly pristine, old-stand forest.)

Looking at 7 individuals from Tippecanoe county (further north), all have 2+2.

inevitable.

Your insight is always appreciated