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Photo#1262569
Two species known from this remote desert locale - Apiocera macswaini - male

Two species known from this remote desert locale - Apiocera macswaini - Male
Antelope Springs, Inyo County, California, USA
July 11, 2016
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.

Images of this individual: tag all
Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini - male Two species known from this remote desert locale - Apiocera macswaini

Moved

Apiocera macswaini
Hello Aaron,

I think this specimen could be confidently identified as Apiocera macswaini. The two pictures of the male terminalia really make it clear. The long, weakly setose hypandrium (9th sternite median projection in Cazier) excludes A. haruspex which has a much shorter and much more densely setose hypandrium. The only other possibility is A. exta which can be eliminated based on the locality and the length of the hypandrium and the shorter lateral membranous extensions.

Apiocera Mouthparts, Drinking, and Feeding Info
The three quotes below from Cazier(1) are of interest and relevance in reference to the Apiocera post here:

1) Regarding structure of mouthparts and the implications for feeding...

"The mouthparts of Apiocera are similar to those of the housefly in that they have a prominent fleshy labium terminating in a pair of corrugated sponging organs representing the labella. This muscoid sponging type of mouthpart is unsuitable for penetrating the nectaries of flowers or for consuming pollen grains. They are more suitable for taking in liquids and dissolved substances by capillary action on the labella. Such an assumption seems to be supported by the fact that the flies drink water and sponge honey-dew from beneath aphid infested plants, the latter being the only known food source of adult Apiocera."
Had I been cognizant of the above in the field, I would have checked for aphids or other honey-dew producing bugs in the Atriplex under which our apiocerid was hopping around.

2) Regarding drinking...

"As mentioned above the adult Apiocera drink water and are attracted to it, a feature that has been exploited in collecting the flies in some dry desert areas. Lavigne (1975) suggested that these flies are scavengers based on their behavior pattern of placing their sponging mouthparts on the soil. To date, there is little to support such a suggestion, even though it may be true, but we know for a certainty that they feed on insect honey-dew and on water. They may be getting some nourishment in the water, as suggested by Lavigne (1975), but this would seem to be incidental since they have been seen sponging it up on such surfaces as sand, soil, twigs, rocks, and concrete freshly splashed with well-water and therefore too new to have absorbed any nourishment from the substrate. In their natural habitats containing available water, i.e., in streams, lakes, and springs the flies visit the damp sand or soil placing the labella on the surface for from several seconds to several minutes at a time."
3) Regarding the name "flower-loving flies"...

"In at least one general entomological text, these flies are referred to as being "flower-loving flies", a misnomer that conveys the false impression that they are frequently found on flowers where they may be feeding on pollen and nectar. In the many hundreds of specimens collected by the writer and his associates in habitats replete with flowers, not one single specimen of Apiocera was collected on a flower. However, in other material examined: one specimen of trimaculata Painter bears a label stating it was collected on Melilotus, sweet clover; a specimen of calida, new species, had a few cream-colored pollen grains on its legs and ventral surface; and one specimen of macswaini, new species, had several Asclepias sp. pollenia adhering to its tarsi, indicating a visit to a milkweed flower. It is doubtful that these few records suggest more than casual visits to flowers even though the flies are evidently attracted to sweet odors."
However, note that one current BugGuide Apiocera post *does* show a female that clearly appears to be nectaring on Eriogonum flowers:

   

Moreoever, the Flickr posts below suggest that *Australian* male & female Apiocera may commonly nectar on flowers:

    Jean and Fred Australian Apio     Jean and Fred Australian Apio     Jean and Fred Australian Apio     Jean and Fred Australian Apio     Jean and Fred Australian Apio

But note that the long, narrow, "sipping" mouthparts of the Australian species above appear quite different from the short, lapping mouthparts of nearctic species. (Perhaps the above Flickr posts may be misidentified, and belong to a different genus? Seems such a significant difference in mouthparts and feeding behavior, together with such extreme geographic disjunction, would lead to classification in distinct genera.)

Postscript: Torsten Dikow responded to some of my questions above via email. In particular, he referred me to the 1996 paper:

  D. K. Yeates and Irwin, M. E., “Apioceridae (Insecta: Diptera): cladistic reappraisal and biogeography”, Zoological Journal of the Linnean Society, vol. 116, pp. 247–301.

...which reorganized the prior taxonomy and treated Apioceridae as consisting of a single genus Apiocera with 4 subgenera, corresponding to the 4 distinct regions where they are found:

      1) subgenus Anypenus, 4 spp., South America (Chile, Argentina)
      2) subgenus Apiocera, 74 spp., Australia
      3) subgenus Pyrocera, 68 spp., Western North America (British Columbia, Western U. S., and Mexico)
      4) subgenus Ripidosyrma, 3 spp., South Africa

Torsten remarked that one could easily raise the above subgenera to genera instead, but it wouldn't change the overall information content, and that he is inclined to leave the subgenera rankings as they are, because a change would not serve any purpose as far as improving understanding of relationships...since, again, the relative information content would be the same.

Also, in reading Yeates & Irwin I noticed they did indicate that the Australian species of the nominate subgenus Apiocera do differ from the other 3 subgenera in having a more elongate proboscis. And though I didn't notice any discussion of different feeding behaviors, I would speculate the the elongate proboscis of subgenus Apiocera might also correlate with more substantial flower-visiting and nectaring behavior pattern in that Australian subgenus, compared to the other subgenera.

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