Thread subject: Diptera.info :: Ocelli Lit Up Blue
Posted by Stephen on 24-10-2006 15:02
#1
Looks similar to a Hydrophorus sp. I photographed. Is that what this fly is?
What stout leg spines! The eyes have a lot of white hair on them. Another interesting thing is that the ocelli lit up blue, in all the pictures I took of this fly (they are flash pictures).
On the shore of a pond, in the mountains, West Virginia, USA, on 16 August 2006. Length 5 mm.
Edited by Stephen on 25-10-2006 17:43
Posted by Stephen on 25-10-2006 17:45
#2
Rats, no comments.
Surely a Doli, anyhow, with the long legs and the leg spines and the pond shore habitat? Those spines seem more extreme than most I've seen on a Doli.
Posted by Tony Irwin on 25-10-2006 19:19
#3
I'm no doli expert, but I'd agree with your family diagnosis. As to genus, I expect a US doli person may recognise those particularly spiky legs, but they're not familiar to me.
Posted by Kahis on 25-10-2006 19:33
#4
First thoughs say
Tachytrechus, but they are notoriously unreliable. None of the critical characters are visible and I'm not al all familiar with the NA fauna.
The metallic blue spots are not ocelli but sides of the ocellar triangle. The paired posterior ocelli can be seen between the blue reflections.
Posted by Nikita Vikhrev on 25-10-2006 20:41
#5
I think it is blue reflection of blue sky by shining surface.
Posted by Paul Beuk on 25-10-2006 21:04
#6
No, the blue is really part of the body colour, not of the sky because you also see it on specimens in collections when no daylight is visible. :D
Posted by Stephen on 26-10-2006 00:14
#7
Just for fun I have enlarged the area around the ocelli and the blue spots. I presume without the flash these would not have been so brilliant.
Nice silver spots too!
I checked to see if I might have a view of this fly from the side but I don't. Next summer I will crawl on my belly through the mud and get a lateral view, which might help with the ID. Maybe a view of the "face" too.
Thanks Tony, Nikita, Kahis, Paul!
Edited by Stephen on 26-10-2006 00:16
Posted by Igor Grichanov on 26-10-2006 10:59
#8
The vertex is shining blue between eyes and ocelli.
The fly looks closer to Paraclius than to Tachytrechus: high hind femur with 1 subapical seta, broad face, middle vein close to wing apex. But some species are still travelling from one genus to another (see Nearctic Catalog, 2004).
Good luck,
Igor.
Posted by Igor Grichanov on 26-10-2006 12:23
#9
Many Dolichopodinae (subfamily) are very spinose. See Dolichopus trivialis.
Igor.
Posted by Stephen on 28-10-2006 12:12
#10
Igor, Thanks for your help with this fly!