several of these feeding on bird-dropping traces on leaves. One specimen collected
No interactions present.
I don't think the face is concave enough for tarsalis. I'll take the picture home and have a look at the key.
thanks John. I've added a couple of images which might help, or not
what key is there for Heleomyzidae? I've seached in vain so far. Apparently there's something in Hungarian, though I've not been able to find it
latest pics and diptera videos
It is either Tephrochlamys or Tephrochlaena. I can't see the dorso-centrals clearly enough, but there doesn't appear to be a pre-sutural dc so I'll assume it is the former. Face is wrong for tarsalis. The stigma looks to be all-yellow, rather than partly darkened. If so, that rules out flavipes, but again a look at the dorso-centrals would help. That leaves rufiventris, which is a common species, and laeta, of which Collin (1943) knew of only two doubtful specimens. The NBN shows only one record of laeta from the Sheffield area.
If it is Tephrochlaena, it is halterata or oraria. I'm not clear whether we have both these species, or whether they are synonyms. T. halterata is in the checklist with oraria as a synonym, but one I had identified by an expert last year was given the name oraria.
If you can get a clear photo of the bristles on the top of the thorax, from above and from the side, it should be possible to settle the matter.
The main British key to heleomyzids other than Suillia is still Collin (1943), which I think was in Entomologist's Monthly Magazine and is possibly downloadable these days.
no pre-sutural dc. Eight rows of tiny acrostichal hairs between an anterior pair of strong dc bristles, which in turn look virtually as long as the other four. The anterior pair are (only just) closer to the suture than to the second pair.
for comparison and key:
Lat/Lng: 51.6039, -0.0758
OS grid ref: TQ333912