What characters are you using to identify Trombidiidae to the exclusion of other trombidioids (Johnstonianidae, Neotrombidiidae, Podothrombidiidae, etc.)? This specimen almost looks like a johnstonianid to me, but I'm still learning trombidioids, and can not differentiate most of the families without slide specimens yet.

I was being a lumper in that comment, calling any relatively large
trombidioid mite, a trombidiid, which is probably the commonest family
in the group. The actual taxonomic characters are fine structure of
the setae and micro-sense organs that are only visible on
slide-mounted specimens.

First, the most common trombidioids are trombiculids, eutrombidiids, and in particular microtrombidiids... NOT trombidiids. Second, it is not accurate to call "large" trombidioids trombidiids. There are plenty of large velvet mites that are in other families, and also small trombidiids. Regardless, this specimen is not large (~2mm), and doesn't qualify.

Second, many trombidioids can be IDed to family by photograph without need of slide preparation. One example is Dinothrombium (Trombidiidae). I don't know of any other desert dwelling velvet mite that even approaches that size (they can get huge: >1cm). Another example are the microtrombidiids that have bulbous setae (e.g. 177478), or eutrombidiids with a pygidial sclerite (e.g. 181073, or trombiculids with the classic figure 8 body (e.g. http://www.fcps.edu/islandcreekes/ecology/Arthropods/Chigger/chigger_adult_l.jpg). Even some trombidiids are can be guessed accurately.

However, with a group like Trombidioidea, which has such an enoromous amount of misconceptions and misidentifications even in primary literature, I don't think "lumping" in your sense is a great idea. For one thing, we already are "lumping" when we correctly identify them by superfamily. No need to blatantly misidentify something just to put a family name on it.

This looks more like a johnstonianid or microtrombidiid to me anyway. For now, until someone knows the beast, or IDs one from a slide... let's put it back into Trombidioidea.

thanks Ray.