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I badly need a second opinion on this Tachinid. It was captured yesterday (16. vii 2011) while feeding on Pastinaca sativa in a dry meadow in the middle of deciduous forest not far from Copenhagen.
The fly is really quite distinctive with the brownish infuscation along the front of the wing; the scutellum has five pairs of marginals. The subapical pair is converging. The apicals are weak and hair-like; the basal part of the arista is thickened and yellow; palps yellow. Body length ~ 4 mm.

It keys out without much trouble both in the Central European key and in CMPD but the result is surprising (or outrageous) and because of this I am wary. If I'm right it expands the range of the species quite a bit – a result of global warming one would say.
I won't give away the species I arrive at yet, but let you guys have a go at it first!

Some features not seen in pictures:
-prosternum bare
-occipital hairs black but some light hairs present ventrally above posterior mouth edge

I am very interested in hearing your opinion before I divulge my outrageous species name ;)

Regards,

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Go on - give us a clue - you've had the advantage of being able to key the specimen under a microscope so you have seen things like the bare prosternum or parafacial that are not visible/clear from the photos. If we just follow your list of features then we will only end up in the same place as you. ;)

It certainly doesn't look familiar to me so it's something unusual. :)

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Well, that was exactly why I didn't want to suggest a name. You would all rush to the relevant couplet in the key and then work your way backwards ;) Like I do alot!
Okay, here goes... This should be Paratrixa polonica, female.
I first keyed it in Tschorsnig & Herting and didn't really believe it. Then I tried the key in the Manual of Palaearctic Diptera and arrived at the same species. I could of course have made the same mistakes twice, but the approach to this genus differs a bit in the two keys, so I'm pretty confident that I'm right.
If so this is indeed a rare find and well outside the range of the species given in Tschorsnig & Herting.
But have a look at it now :)

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It should be Eloceria delecta.

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Eloceria delecta should have strong scutellar apicals, shouldn't it? This baby has very weak and hair-like apicals and strong subapicals.
A thing I forgot to mention is that it has only 2 ia closer together than the distance from the suture to the first one. And only 2 humerals also.

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Can you plese make photo of the wing?

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Here you go!
Left - upper side. Right - lower side.

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Paratrixa is in Exoristinae, so it should have setulae on prosternum. Following your description prosternum is bare! Please check, if your species really has palps, because delecta female should not have palps.

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I'm back. I've had a new good look at the fly and there really are no palps. What I thought were palps are just some folds on the proboscis. So it should be Eloceria delecta – which by the way is also a very delectable find. At least in Denmark this is a rare fly.
But I'm still puzzled by the keys. What I took to be the apicals on the scutellum apparently don't count as apicals and my converging subapicals (one is missing) are really the strong crossed apicals. This is unfair ;) Forgive me for quoting the couplets in CMPD and the Central European key:

222 Subapical scutellar bristles not extending back to level of apices of strong crossed apical bristles

-Subapical scutellar bristles extending back at least to level of apices of apical bristles; the latter may be absent

107 Die Subapikalen des Scutellums reichen nicht so weit nach hinten wie die starken, gekreuzten Apikalborsten. Flügel: Der Abschnitt von M zwischen R-M und M-Cu ist kürzer als der zwischen M-Cu und der Beugung

-Die starken Subapikalen des Scutellums reichen wenigstens so weit nach hinten wie die Apikalen, die auch ganz fehlen können. Der Abschnitt von M zwischen R-M und M-Cu ist wenigstens so lang wie der zwischen M-Cu und der Beugung

I naturally chose the second option in both keys leading away from Eloceria delecta and eventually to Paratrixa polonica. The difference in the proportions of M should perhaps have halted me...

You have been most helpful, Erikas. Thank you very much!

Regards,

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Just a thought... If this is Eloceria delecta http://www.dipter...d_id=22950 then mine cannot be or vise versa unless of course sexual dimorphism is that pronounced.

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Yes, it is because of a distinct sexual dimorphism. You have a female.

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Splendid! Another mystery solved.
Thanks again.