This single male was found due to the remarkable field search skills of Joyce Gross. Joyce somehow noticed it, as it hopped (every 10–40 seconds or so) within a small dome-like space under the canopy of a four-winged saltbush (
Atriplex canescens). The small area within which it was active was mostly obscured from above by the fairly dense twigs of the saltbush, but was more visible in lateral view from ground level...which is the view in which these photos were taken.
This is the type locality of
Acrocera macswaini, but
A. haruspex atrifasciata has also been recorded here. Most the detailed characters used in the keys, descriptions, and discussions in Cazier
(1)(1982) refer to details of the male terminalia, usually enclosed and obscured by the hemitergites (= the two large exteriorly visible clasping sclerites at the posterior of the abdomen).
This male was intermittently flexing open his terminalia by a small amount in a rhythmic fashion...and I'm hoping some of what's visible in the photos due to that behavior may help in identification. But at this time I can't say for sure whether this is
A. macswaini or
A. haruspex atrifasciata (or perhaps yet another species). The key to male
Apiocera in Cazier
(1)(1982) states in the terminal couplet leading to
A. macswaini:
"Posterior femora entirely or primarily white pilose; compound eyes separated from the lateral ocelli on the vertex by one-half or slightly more than one-half the width of a lateral ocellus"
...which appears to be the case here. But I could find no information in Cazier
(1)(1982) indicating that's not also the case for
A. h. atrifasciata.
The behavior here was somewhat curious & interesting...hopping and dipping into the substrate under the saltbush, seeming to be sampling something within the detritus. I couldn't tell whether he was feeding, imbibing moisture, or perhaps taking some mineral nutrient. Whatever it was, his behavior of periodically hopping to a new position on the ground under the saltbush; tilting his head down and abdomen up; and then thrusting his proboscis in the substrate...was persistent for the many minutes I was observing, and also while Joyce was watching before me.
Apiocera do not have the "stabbing" mouthparts of Asilidae, nor the long nectar-sipping mouthparts of
Rhaphiomidas...it appears to me they're closer to the "lapping" mouthparts of many diptera, but I'm no expert here.