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Does anyone happen to have Lindner's volume V (part 2?) at hand - or in any case that one with Heleomyzidae.
Just that part was missing from the Helsinki museum and I think Andrzej once mentioned that it is relevant here.

My question is: Can Heteromyza atricornis-female be differentiated from H. commixta?

If the descriptions are lengthy, I'd be grateful for the page numbers too, so that I could perhaps order them to the local library.

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If you are referring to Die Fliegen, then Czerny separates commixta from atricornis/rotundicornis on the width of the cheek relative to the frons: in commixta , cheeks as wide as frons, in the othe two narrower. Not terribly helpful and doubtfully useful I would say.

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At time there is the only way to separate the females of mentioned species

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Many thanks to both of you, Phil and Andrzej!

Sorry about the confusion with the name of the series: 90% of my use of it is the Lindner's part of Anthomyiidae (or Muscidae), so I always tend to forget that the official name is "Die Fliegen".

But having a lack of comparison material I guess that this female will remain a Heteromyza sp. and we should collect a male next time!

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I cast one final glance to this female specimen (collected in south-western Finland 10.4. 2010) and noticed that it really had remarkably narrow cheeks, about one fourth of the width of frons in the middle. So that would rule commixta out.

But does Die Fliegen say anything about the differences between rotundicornis and atricornis females? Could their flight period be different - at least the only Finnish specimen of rotundicornis so far was collected in the beginning of August.

Anyway, I'm pretty convinced that this is a Heteromyza atricornis (Meigen)-female, but how to obtain the final proof, that's the question!

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Czerny says "Vibrissae well below lower level of eyes, eyes at level of antennal base not narrowed = atricornis. Vibrissae at lower level of eyes, eyes at level of antennal base narrowed = rotundicornis". Collin (pompous old *** that he was) doubted that the two could be separated in females, but was sure Czerny knew his stuff...hmm.

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Thanks once again, Phil!

My atricornis-theory got a severe backlash since I would say that the vibrissa is at the same level or rather slightly above the lower level of eye.

And I can't really say anything about the other character mentioned. Quoting you, hmmmm...

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Returning to this business after a while: Yesterday in Turku I caught my first male from this pair H. atricornis/rotundicornis. Only the latter has been previously recorded from Finland and it too is here rare.

The vibrissae of this specimen are well above the lower line of the eye and frons somewhat tapering towards antennae - does this mean that atricornis is ruled out?

So, any further wisdom in separating these two species is greatly appreciated...