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fly - Sphecomyiella valida

fly - Sphecomyiella valida
Cross Plains, Dane County, Wisconsin, USA
June 14, 2013
I think this is also Pyrgota maculipennis. I compared it to the photos of a fly I photographed in 2007 and they look similar. Odd thing is that both flies were found in the same area on our deck. This one was quite a bit healthier though.

Images of this individual: tag all
fly - Sphecomyiella valida fly - Sphecomyiella valida fly - Sphecomyiella valida fly - Sphecomyiella valida fly - Sphecomyiella valida fly - Sphecomyiella valida

Sphecomyiella valida vs. Boreothrinax maculipennis
Moved from Pyrgotidae.

It can be difficult to separate images of Sphecomyiella valida from those of Boreothrinax (=Pyrgota) maculipennis. Prior to carefully going through the keys in the MND and Steyskal (1978) to ID the post below...

...I typically focused on the primary, though often hard to interpret, character used in both keys. That is, I'd simply try to assess whether the "the basal third of hind tibiae is tapered vs. strongly constricted". (Actually, I'd also look for the "banded vs. solid colored tibiae" character pointed out by Gary Steck here.)

Now I have (belatedly) started to give attention to the other three characters for separating Sphecomyiella and Boreothrinax (=Pyrgota) that are mentioned in couplet 4 of the MND(1) key...namely:

    1) Sphecomyiella has post-ocellar setae...while Boreothrinax lacks such setae;
    2) Female Sphecomyiella have a sharply hooked apicoventral claw on the 7th sternite of...while Boreothrinax females don't; and
    3) Sphecomyiella have lateral setae on the prosternum...while Boreothrinax can lack, or have, such setae.

I don't know why I didn't pay more attention to those two characters before! Well, then again, maybe I do...they're usually hard to make out in most photos. Especially the hooked claw on the 7th sternite of females, which is usually retracted...and won't help with males :-) And the third item above is only useful in the case where there is no setae, in which case you presumably have Boreothrinax (unless it's a Sphecomyiella specimen that has been roughed-up and had its lateral setae rubbed off! :-)

Anyway...Ilona...the pyrgotid in your post here clearly has post-ocellar setae (see 2nd and 4th images in your series) this is definitely S. valida.

Aaron, You might be interested in the Facebook group "Diptera" (that is if you even use FB.) I posted a photo of this fly for the group and there have been some interesting details posted about these flies.

Ilona, could you provide direct links...
...for the web pages you were referring to? I couldn't find them.

I'd like to read the interesting posts relating to pyrgotids you mentioned (if one can do so without being forced to register for Facebook).

Moved from Pyrgota maculipennis. Based on these comments, I've decided it's best to move these photos back to the Family level for verification. Sphecomyiella valida does seem to be a better match.

Moved from Pyrgotidae.

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