I had to sort through the University of Memphis herp collection and check IDs a few years back. I have those fasciatus complex ID characteristics pretty well ingrained now.
I like P. inexpectatus because you can separate it out at a glance, by vertebral stripe and subcaudal scale width. Now separating P. fasciatus from young P. laticeps - that's tricky. You wouldn't believe how many lizards have five labials anterior to the postocular on one side and four on the other, and some random mishmash of postlabial character states. It also doesn't help when they're all shriveled from being in too-strong ethanol for a few decades. Ugh.