Platypezid Fly

A tiny grey and black fly that looked like it might be laying eggs on fungus growing on rotting logs.  Probably a female Polyporivora picta (Diptera: Platypezidae).  Mainly yellowish legs, weak bands on the abdomen and a black scutellum (not shown well here). Identified by Menno Reemer in the comments below.

The following fly which I photographed in the same area just 4 minutes later is a female Polyporivora ornata.  White scutellum, stronger bands on the abdomen and mainly black legs (not shown well here).

Photos taken in the Wilderness, Whiteknights Park, Reading University grounds, Reading, UK, on 2011-09-25.

Comments

[Menno Reemer]

Hi Tristram,
I think the first picture does not show Polyporivora ornata, but an Agathomyia species (possibly A. cinerea, will have to check). It will be very interesting to know on which fungus you have observed this fly. Is there any chance you might remember?
(The fly on the second picture is a Polyporivora indeed.)
Best wishes,
Menno

[Tristram Brelstaff]

Now you mention it they do look different. I based my identification mainly on the 2nd photo and must have assumed that the first was the same species without checking too closely. I will have a look to see if I took other photos at the same time. I'll get back later.

[Menno Reemer]

Having looked at it more closely, I now realize that I also made a mistake: it is a Polyporivora after all, although it's not P. ornata, but P. picta. Both species are known to develop in Trametes versicolor as a larva, so there is a good chance of finding them at the same spot.

[Tristram Brelstaff]

Yes the first one does look more like P. picta. The yellowish legs and the indistinct banding on the abdomen both match picta much better than ornata.

Thank you!