I saw a few of these on the sand between shrubs. I think this one is a female, from the look of the terminalia...is that right?
I could key this clearly in the Manual of Nearctic Diptera(1)
to tribe Asilini via the following characters:
R2+3 joining R1 proximal to end of R1, with cell r1 thus separated from wing margin.....63
Apex of antenna with long slender bristle-like stylus; apex of cell bm usually closed by only two veins...74
Antennal stylus bare (i.e. not plumose)....75 (Asilini)
The next couplet, 75, asks if anatergite is bare vs. pilose...which wasn't clear to me from my images. If I follow the "anatergite bare" lead, I get to genus Proctacanthus
. If I follow the "anatergite pilose" lead I'm not able to get a clear result.