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Is this Heteromyza rotundicornis (also known as atricornis).

Seen in the UK, February 2015.

(The fly is actually hanging nearly vertically. One of the hind legs has a loop of spider's silk around the apex, which is why the leg is extended. At the time, I thought it was cleaning itself!)

Nigel

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view of venation (just about adequate)

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general view, with abdomen exposed

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view of head

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close-up of rear end

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Heteromyza rotundicornis and H. atricornis are not synonyms, they are separate species.

The eyes are too close together on yours for rotundicornis, so it's either commixta, atricornis or oculata. The presutural dc appears well-developed, so that would make it commixta or atricornis. H. atricornis is a recent addition to British fauna so there's no key to separate them

here is an example of H. rotundicornis http://www.dipter...d_id=64892 you can see the eyes are very widely-spaced

Jeremy

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Hi Jeremy

I am puzzled by this. I checked the NBN Gateway, then browse species for Heteromyza.
Both H. atricornis and H. rotundicornis have a preferred name of H. rotundicornis. Which to me implies they are the same.

I agree mine doesn't look like the flies in the link - eyes too far apart. But I cannot see any differences, down to the smallest details, in this thread -

http://www.diptera.info/forum/viewthread.php?forum_id=5&thread_id=26428

Is there an explanation for the species name confusion? Is there any feature I can look for in my images that might help further?

Nigel

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On the British list atricornis is given as a misidentification of rotundicornis. There another two British species in the genus (http://www.dipter...p?id=10823) but I do not have a key at hand.

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as Paul points out atricornis appears on the checklist as a misidentification. So NBN is referring to that error, not to the atricornis which exists as a separate species, and has yet to be officially added to the British list as a fourth species.

So yours should be commixta or atricornis, however the European key contrasts 'slightly' with 'gradually' so looks like a poor translation and nobody seems to be able to make head or tail of it. Dr Andrzej Woznica is a specialist on the family so he might be willing to explain what the differences are

Jeremy

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I'm totally confused too.

The Russian key merely translates that of Czerny (1927), which makes little sense, even in the original German. However Czerny did provide figures of the frontal view of the male heads of all 4 species. While the frons of atricornis and commixta don't look much different, the faces do. Based on those figures, Roger Thomason's fly looks like commixta, not atricornis.

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Thanks for all your helpful comments, though I also have to admit that I am confused too.

It doesn't seem to be a satisfactory state for things to be in, though it may be a more common situation than I realise. I did (a week or so ago) come across a related fly, and since I had the specimen, I asked about keys. The advice I was given didn't get me anywhere. It was just a dead end. So this seems to be a problem area, which I think I had better keep clear of in the future. (maybe that sounds a bit pathetic, but I know my limits!)

Nigel

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I can't find 'frontal view of the male heads of all 4 species' anywhere online that would be extremely useful. H. commixta is apparently the commonest northern species though so that's probably the most likely

I'd suggest keeping specimens though till it becomes clearer, which it will..

Jeremy

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I will now make an attempt to capture any I come across, Jeremy. Though I do not always carry around stuff to capture it in, since I prefer to carry a heavy camera and tripod! I do not have a good history of capturing things (beetles, bugs, bumblebees, etc). If I do capture one, rather than photo, I then find it wasn't necessary anyway. And if I don't, then I should have done.
:|

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The same figures are included in Czerny's earlier work here (on the last page). In fact the quality is a lot better and it is possible to detect the differences in the shape of the frons as well, albeit subtle.

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I've finally figured out how to distinguish the males of the 4 Heteromyza species and I'm now convinced these pictures are of H. commixta.