Turquoise-striped Syrphid- Didea sp? - Megasyrphus laxus

Moved

… Denis A. Doucet, 29 August, 2014 - 11:38am

Moved

… Kelsey J.R.P. Byers, 10 August, 2014 - 2:10pm

At first I went "Oh man, Dide

At first I went "Oh man, Didea alneti!" (since the only photo we have of that species is also turquoise). However, the pale markings extending to the edge of the abdomen, darker frons (barely visible), and oval rather than tapered basoflagellomere indicate Megasyrphus instead.

Regrettably, Vockeroth only mentions Megasyrphus laxa, and the key that includes the other Nearctic species (Megasyrphus catalina) is not available in English. Vockeroth does mention that some individuals are greenish-yellow rather than yellow in the abdominal markings, but this is more greenish-blue... unsure why.

Moving to genus for now.

… Kelsey J.R.P. Byers, 10 August, 2014 - 2:09pm

Thanks, Kelsey!

Is the key you mention in French? If so, I can read that (it is my mother tongue) and perhaps bring this to species. Could you send me the link? ALso, I am adding one more image which shows the wing venation of R4+5 better, confirming that it is NOT Dideomima.

… Denis A. Doucet, 10 August, 2014 - 2:16pm

Alas, it's in German (I have

Alas, it's in German (I have some French, though very little, so would try myself, though doubtless you'd do much, much better!):

Dusek, J. and Laska, P. 1967. Versuch zum Autbau eines natiirlichen Systems mitteleuropiischer Arten der Unterfamilie Syrphinae (Diptera). Acta Scientiarum Naturalium Academiae Scientiarum Bohemoslovacae, 1: 349-390.

Great shots! Thanks for the extra photo too - it also shows the frons which is yellowish in Didea and black in Megasyrphus (and here). And I see that several other Megasyrphus also have the greenish-blue color...

… Kelsey J.R.P. Byers, 10 August, 2014 - 2:42pm

Thanks again!

I may give that German one a whirl. I did 2 years worth in university, but I imagine that was not technically oriented enough to help. Interesting that several of the other blue-green striped ones were from Maine (next door to us).

… Denis A. Doucet, 10 August, 2014 - 2:45pm

Well, diptera.org notes that

Well, diptera.org notes that Megasyrphus catalina is found in Arizona only - though that's probably because that's the type locality. I'll take a look at Curran's description and see if it differs obviously from Megasyrphus laxa/laxus...

Okay, found it quickly. Curran notes that it's "Related to laxa Osten Sacken but the lower half of the front is reddish yellow and the legs are much less black... second and third reddish yellow abdominal bands entire..."

… Kelsey J.R.P. Byers, 10 August, 2014 - 3:55pm