#4
This robber has been observed in REGUA a few times before (e.g. https://www.inaturalist.org/observations/8382773, https://www.inaturalist.org/observations/8895809).
Important characters I can distinguish: cell m3 appears to be closed (more obvious in Flickr photos), anatergite is bare, and marginal scutellar bristles are absent. Using Papavero, Artigas & Lamas (2009) this would key out to Phonicocleptes/Blepharepium, which is obviously wrong. Assuming cell m3 is actually open, it would key out to Tocantinia, which is also not quite right (marginal scutellar bristles are present in that genus). So, unless I'm missing something, I would guess this is also an undescribed genus.
#5
Thanks much for the tentative det and detailed info Chris. I had seen those other shots and they drew me to that area.
I actually have a really nice series of one of these (first shots = https://www.flickr.com/photos/7432824@N07/49484514878/) that I will post soon. If I remember correctly I think I have some dorsal shots.
#6
After looking at the newly posted Flickr images of the male, I believe I missed an important detail in my initial ID - the antennae. There is only one flagellomere (not two as I originally assumed), and what appears to be a small dorsal spine. Taking into account the wing venation (cell r1 open and cell m3 closed), this would key out to
Cyrtophrys. This genus seems to be a pretty good match based on the illustrations of the antennae and head that I have seen, as well as the description in Hull 1962. It has also been collected in Rio de Janeiro. At the current time that is my best guess for the identity of this fly. Cool!