jeremyr's picture

Polyporivora picta

Observed: 5th November 2012 By: jeremyrjeremyr’s reputation in Invertebratesjeremyr’s reputation in Invertebratesjeremyr’s reputation in Invertebratesjeremyr’s reputation in Invertebratesjeremyr’s reputation in Invertebrates
Poliporivora picta
Poliporivora picta 2a
Poliporivora picta 5
Poliporivora picta 6
Poliporivora picta 4
picta female hind tarsus
Description:

These flies are usually seen running about on the surface of leaves. Their maggots feed on the fungus Turkeytail

Identifications
Species interactions

No interactions present.

Comments

ophrys's picture

picta

There is also ornata to consider, but I do not know what the difference is between the two...I think they are quite similar?

Ian
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jeremyr's picture

ornata/picta

The NBN map is fractionally more encouraging for ornata than picta, but both seem sparse. I'm guessing that's more to do with under-recording due to a late flying season? There's an image here of ornata, it seems to have a pale scutellum, whereas the other images of picta I've seen have it black:
http://www.diptera.info/forum/viewthread.php?thread_id=30862&highlight=P...

plus it's described as 3.5mm, significantly smaller than this one which has an abdomen length of 4.5-5mm (not including head)

Apart from that I can find no key. Is there one on dipterists forum for subscribers I wonder.

Added are some images of the mounted specimen. Some impressively large dark clubs on the halteres, I notice. The flattened hind tarsus is visible, and a strange tiny red lump on the thorax

Looking more closely the scutellum is definitely black, and white on images of ornata. I wonder though if it's that simple..

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grant burleigh's picture

ornata/picta

This will be a female; the males of both picta and ornata are black (see Diptera.info)

jeremyr's picture

ornata/picta

ophrys's picture

picta

Yes, I agree that picta looks more likely, and the scutellum colour appears to be relevant.
Chandler 2001 seems to be the key: The Flat-footed Flies of Europe (Fauna Entomologica Scandinavica)

http://www.amazon.co.uk/Flat-Footed-Flies-Diptera-Platypezidae-entomolog...

Only £92 on Amazon!

Ian
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jeremyr's picture

female Polyporivora

"2. Thorax with a broad black median stripe reaching scutellum, which is also mainly black above. Abdomen with T2 often bearing a pair of small grey spots dorsally; T3-5 with triangular black basal markings, that on T3 extended to hind margin...... 'picta' (Meigen)

Thorax with dark median stripe narrowed behind and ending well short of scutellum, fused in front with lateral dark markings to form tridentate pattern; scutellum without black marking. Abdomen with T2 entirely black dorsally, T3 broadly black in middle dorsally and T4-5 with basal black bands...... 'ornata' (Meigen)"

(Fauna Entomologica Scandinavia, Volume 36, pp.196-7 by Peter Chandler, Brill 2001)

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ophrys's picture

picta

Perfect! Good to see the relevant couplet.

Ian
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