Better pix from Dave show that this critter is Streptocephalus sealii.

as they are very adamant that that's not their job and that that's not what they did. They claim something to the effect of there being no real evidence that it's extant, rather than that that there is good evidence that it's extinct.

Not so. The USFWS has not declared Streptocephalus seali to be either extinct or endangered. They have placed a species of Streptocephalus, namely Streptocephalus woottoni, on the endangered list, but it is obviously not this one. There are many species of fairy shrimp in the genus Streptocephalus, just as there are many fish, for example, in the genus Percina. The renowned snail darter, Percina tanasi, is one such species and it was once classified as endangered (now listed as threatened), but many other representatives of the genus are NOT listed in either category.

I am personally very familiar with S. seali, having studied them on FEDERAL property where they are enormously abundant and having developed methods for collection of their eggs from pond soils. These crustaceans can provide a valuable seasonal food source for fingerling bass and other carnivorous fish species propagated on fish hatcheries. Their springtime population explosions happily coincide with the time of year when hatchery-raised largemouth bass need plenty of live food of appropriate size in order to grow to stockable sizes.

when I mentioned USFWS. See John's comment above.

but I just posted two cropped head shots and will try to get better male head shots tonight.

These are much better shots - BUT because I'm no expert on fairies I can't really say much more without actual specimens under my scope, where I can dissect out the second antennae and frontal appendages. The new shots do appear to rule out Dexteria, but ... these critters aren't my bailiwick!

although that would be cool, but posted them more for a gestalt of live ones for after specimens are ID'd.