Large coreid - Acanthocephala thomasi

Well...

I'm reconsidering what I wrote here because that image shows a broad hind tibial flange that extends full-length, like the picture of A. declivis here, taken from the key at the bottom of this page.
Your specimen also shows a broadly expanded pronotum (or at least, more evident than the other photo), similar to the pic of A. declivis here.
So where are we at now? A. declivis? or A. confraterna?

… Robin McLeod, 6 February, 2005 - 6:12pm

another species?

After looking at the sites you referenced and some others, and at the two specimens of the Arizona bug in my collection, as well as a specimen of what I think must be A. confraterna from Oklahoma in my collection, I've noticed the following...
The hind tibiae of A. confraterna are too wavy in outline and the hind femora lack the big spine that the AZ bug has. The pronotum of A. declivis is quite a bit wider than my AZ bugs, and the hind tibiae have a more pronounced flare proximally than the AZ bugs. The AZ bugs' hind tibiae are more uniform in width than any of the other species. Could this be a different Acanthocephala species entirely? I made some edits to my original post since we don't know what it is yet!

… Robyn Judith Waayers, 6 February, 2005 - 8:19pm

A. thomasi maybe

As Eric suggested. There's a photo here that shows brown elytra and a femoral spike, as in your photo. The other photo that appeared in a Google search for "Acanthocephala thomasi" (the bugsincyberspace link) worked several months ago but is dead now. The thumbnail still appears in Google, and you can see a nymph below the adult. The full image, when it worked, showed a monstrous bug with gigantic hind legs.

… Robin McLeod, 7 February, 2005 - 12:49pm

looks more like it

The image on that site you pointed out does look more like my specimens. And apparently it is a Western bug. Fits better!

Thanks all.

… Robyn Judith Waayers, 7 February, 2005 - 6:11pm

A. thomasi

This one can be IDed by the process of elimination: it's not A. declivis because it lacks greatly expanded humeral processes, as shown here. It's not A. femorata because that species has entirely reddish antennae, as described in the key on this page. And this one has a parallel-sided flange on the hind tibia, unlike the wavy tapered ones seen on A. confraterna and A. terminalis. There's only 5 species in North America, so A. thomasi wins by default. The location (Arizona) fits too. Moved to Guide page.

… Robin McLeod, 1 May, 2005 - 4:03pm

A. thomasi?

Carl Olson, in his book, "50 Common Insects of the Southwest," lists A. thomasi as the caption to his photo. This can be a difficult genus, and remember that males (as this specimen is), differ from females in the degree of expansions on the hind legs.

… Eric R. Eaton, 7 February, 2005 - 11:38am