Gopher snakes mating (? see comment below) in backyard for at least 1.5 hours (I did not watch the whole time, but had to keep dog inside until they decided to go back to the canyon). Video taken with phone:
https://youtu.be/EwRPn0ePzJg

Playing around more with the white backdrop, this time using my own personal H arizonensis named Petey. This scorpion stung my boot when I first met him, but he cooperates quite well now, and lets me pick him up with no fuss. These are the only two photos that I could actually manage to take because this scorpion decided to haul ass in any direction that wasn't my wobbly PVC backdrop. I have a hypothesis for when I do this in the future. If I can get the scorpion in a cup and use my piece of clear acrylic as a lid, I can gently turn the cup upside down so the scorpion will come to rest on the clear plastic. Then, once it calms down I can lift the cup off and take a picture while it's shocked still. Otherwise, I couldn't get Ol' Petey to stay on my plastic platform whatsoever without him skittering away at full tilt like a Scooby Doo character.

I'm fairly certain that this scorpion is Smeringurus aridus. In appearance, this particular example was noticeably large, being by my approximation slightly larger than most adult male mesaensis I've encountered. When I first discovered this individual, it was extending its pedipalps from a shallow burrow. I carefully excavated the surrounding area and gently removed the scorpion from its burrow to examine in more detail.

The weak scalloping of the fingers very closely resembled illustrations depicting S aridus. There appear to be 26 denticles in the sixth row of the fixed finger. I placed plastic wrap over the scorpion and took the included picture of its genital papillae. It's not quite as pronounced as I would have thought, but appears almost identical to the papillae of the Smeringurus vachoni immanis that I came across later in the night, and have also included a picture of. Although not particularly relevant, I also included a single image of the genital operculum of a Smeringurus mesaensis male just for comparison's sake. If you are not certain which one is which, I watermarked the lower left corner of those images with the species name being depicted.

I was feeling fairly fancy that night and decided to bust out my new-fangled mobile photo studio. If you knew what it was actually made of you'd probably have a good laugh at how ridiculous it is, but it was such a pain in the ass to set up that I took a lot of pictures to offset the effort. I hope you'll excuse me for it, lol. This was the only adult male I found that night, so that is why it received special treatment in particular. Now that I have reviewed the pictures produced from my mobile "photo studio" ($4 home depot drop cloth) and I'm happy with the results, I will now keep it set up in my trunk for future use.

I ended up in this particular area after being swarmed by some kind of cicada-like insect at the original spot. I'm obviously not afraid of bugs, but spending half an hour with hundreds of tiny insects constantly crawling all over my skin took its toll on me, not to mention I couldn't even take any photos because the scorpions were chased off by the horde constantly flying into them. I drove around for a while and took a wrong turn and got lost. I eventually ended up in this location where the aridus was found. I can confirm the location is accurate because because I had used GPS to pin where I parked my Jeep. An interesting fact about this locale in particular is that a majority of the surrounding hills are largely featureless and devoid of vegetation. There are little to no rocks or debris for the scorpions to hide amongst, and so the hillside was littered with active burrows. The soil was very soft, which likely accounted for the high density of these burrows. The visibility was amazing, and I found an absolute treasure-trove of other Smeringurus aridus of different sexes and instars, as well as a few Serradigitus joshuaensis hiding in the cracks and pits in the hillside. It is worth noting that although the initial trail which leads into Smoke Tree Wash can be driven on normally, it quickly becomes a very deeply sandy trail which is traversable only by a 4WD vehicle. It is however relatively close to the trailhead, so I imagine those of us without 4x4 could easily walk to this location. It would have added to the mystique if I had found aridus somewhere deep in the wilderness, but I think it's better this way, don't you think? If you're looking for aridus and found any of the info here to be useful, please leave a comment on this post, I would really appreciate it!