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Posted by nick upton on 10-10-2014 22:50

Can anyone help me to identify these picture-winged flies I observed today mating (in a threesome…), and males wing waving and fighting by grappling then head-pushing and rising up together. There were a number on an old tree trunk, possibly breeding in crevices in the bark in an ancient woodland. ?? Pallopteridae

10.10.2014 c8mm Wickwar, Gloucestershire, UK

Edited by nick upton on 11-10-2014 11:17

Posted by nick upton on 11-10-2014 11:23

Many thanks Piet for this quick definitive identification. This is a new family to me - and this fly is rarely recorded in the UK, but no doubt much overlooked as it was very well camouflaged on the old rotting tree I found it on. I will inform the nature reserve where I found it ( a famous ancient woodland in Gloucestershire) and the county recorder. The behaviour was fascinating to watch - and I have now found a nice vide clip on wikipedia: http://en.wikipedia.org/wiki/Clusiidae although what I saw was more advanced with pulling and head pushing contests. I may go back to try and get more shots / video myself. Also good to see other observers on this site thought it might be Pallopteridae, though I had a feeling the body shape was wrong.

Posted by jeremyr on 11-10-2014 11:59

Incredible pictures!
I found it in Epping Forest this year whilst watching for Xylomya. Apparently the species develops in rotten wood and was formerly considered scarce but is now quite widespread in southern England.

Jeremy

Edited by jeremyr on 11-10-2014 12:05

Posted by nick upton on 11-10-2014 12:11

Many thanks, Jeremy. Yes, I read it was on the RDB2 list until recently, but it is either becoming more common (maybe a warmer climate favours rotting wood…) or observers are becoming more alert about where and when to look for it. I was actually out photographing fungi (with macro lenses/flash kit at the ready!), but got heavily distracted by one tree base which as well as a big bracket fungus had 2 kinds of wasp coming and going (Ectemnius cephalotes, a rotten wood specialist) and a smaller one yet to be identified and what I think is a Tachinid sniffing around, yet to be Idd and only after 15 mnins of photographing that lot did I notice some wing fanning and the odd 3some mating trio of these flies and switched my attention to them. I've seen some tropical flies lekking/competing a bit like this but never in the UK before. Now working on another little orange fly on a toadstool. Heleomyzidae I think...

Posted by jeremyr on 11-10-2014 12:22

:)btw it's Clusia on our checklist
Triarthria is a tachinid that likes sniffing around old wood, or Phytomyptera if it's very small. I'll look forward to you posting it? You probably found those little orange Chryomyids hovering about as well in that habitat, with very iridescent eyes

It's usually Suillia sitting on toadstools
http://www.diptera.info/includes/bbcodes/images/smiley.png
Jeremy

Edited by jeremyr on 11-10-2014 12:23

Posted by nick upton on 11-10-2014 12:43

#10

OK thanks. NBN gateway still has it as Paraclusia, but is Clusia a more accepted genus name they haven't noted yet?

I got to Suilia before i read your response, so may have got close… and S. bicolor looked a possibility.

My tachinid looks good for Triarthria, will post soon.

Posted by jeremyr on 11-10-2014 12:55

#11

I think nbn sometimes lags behind the 2012 Checklist (although the Clusiidae section is unchanged since 1998, with Paraclusia still as a junior synonym) but I'm not sure.
Perhaps there's disagreement between the two instututions..

Posted by nick upton on 11-10-2014 13:12

#12

OK many thanks, I'll record it a s Clusia tigrina when I let the reserve know. I didn't really notice chryomyids specifically, but yes there were some littlies hovering around.