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Mating Robber Fly Pair - Lasiopogon monticola - male - female

Mating Robber Fly Pair - Lasiopogon monticola - Male Female
Jordan Peak, Tulare County, California, USA
June 10, 2012

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Mating Robber Fly Pair - Lasiopogon monticola - male - female Mating Robber Fly Pair - Lasiopogon monticola - male - female Mating Robber Fly Pair - Lasiopogon monticola - male - female

Moved from Lasiopogon.

You were right, the halter is completely light. Dr. Cannings said he'd call these L. monticola.

Here's the quote: "I’d say that the California species is L. monticola. In the Sierras many specimens have rather red terminalia and tibiae/tarsi, somewhat like the species of the testaceus group. It’s not L. fumipennis – that has a medial line on the scutum and a dark halter spot. The epandrium [in L. fumipennis] is shorter and stouter than this one, too – kind of “inflated”."

These are great shots for the guide!

Thanks for pursuing this, Tristan...and thanks also to Dr. Canning for the ID and informative comments.

Now I'm trying to figure out which is the male and which the female here!

Regarding the terminalia visible in my photos (open this link and click image for detailed full-size view)...I'm presuming the somewhat tubular ventro-lateral processes are the male gonopods or "claspers" (see "8+9" in Fig. 1 here). Or perhaps those tubular processes are lateral portions of the epandrium? Either way, I can't tell which fly those claspers are attached to from the photos. However, presuming the setae on the claspers are oriented in the posterior direction, I'm guessing they're attached to the fly on the left.

So, I guess the fly on the left is the male...correct? Or course, the holoptic eyes character for males doesn't work for robbers, and I count the same number of banded terga (6) on both flies. The fly on the right does look a bit larger to me, and if I'm not mistaken the females are often larger in Diptera.

Lasiopogon don't play fair
Lasiopogon don't play fair-- they usually have rotated genitalia. So the longer claspers you're seeing on the bottom are actually the epandria (no. 5 on the Geller-Grimm figure), while the short ones on top are the gonocoxites. The gonostylus in Lasiopogon is usually very short and hidden inside.

The fly on the left is indeed the male. The hairs usually point posteriad, and you can see that the epandria directly abut the last tergite. And yes, the female is often a little bigger in flies. Also, if they try flying away while still conjoined, the female will usually be the one driving.

Moved from Robber Flies.

Nice Lasiopogon pair. I want to say they're L. fumipennis (because of the red genitalia, reddish tibiae, and strong tergite banding), but I'm not positive. I can't see the halter spot, for one thing. Let's see what Rob Cannings has to say.

Thanks for the ID, Tristan. I'm not sure what the halter spot is, but as you probably saw, the halter knob is very pale yellow to white. A link to larger image is here.

Inadvertent duplicate comment (these can't be deleted).

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