Diptera.info

Posted by jezlee on 27-07-2010 10:34

Hello all - I think this could be Phasia obesa - or does it just look like it? I'm not at all sure ... :)

Edited by jezlee on 27-07-2010 10:35

Posted by ChrisR on 27-07-2010 10:47

I think this is Graphomya cf. maculata - a muscid ;)

All Phasia spp. have a stalked/petiolate median vein.

Edited by ChrisR on 27-07-2010 10:49

Posted by jezlee on 27-07-2010 12:00

ChrisR wrote:
I think this is Graphomya cf. maculata - a muscid ;)

All Phasia spp. have a stalked/petiolate median vein.

BUGGER! :o

Thanks, Chris! Any chance you could explain further what you mean by "stalked/petiolate median vein"? :)

Posted by ChrisR on 27-07-2010 13:12

Sure, if you look at your first photo you'll see that there are loads of radiating veins but the 2 we are interested in are the 2 longest veins that radiate out and diverge slightly - the top one of the pair is called r4+5 and the lower is called the median vein. The median vein bends up slightly and almost meets r4+5 near the wing tip - this is the commonest arrangement and is *not* petiolate.

On all Phasia the median vein meets and joins the r4+5 vein well before the wing tip and r4+5 runs on to meet the wing-tip alone, in a stalk or 'petiole' ... this is petiolate :)

If you have a look in the gallery you should find it's fairly easy to spot with experience - if you have trouble I can PhotoShop some pics for you :)

Edited by ChrisR on 27-07-2010 13:12

Posted by jezlee on 27-07-2010 13:51

ChrisR wrote:

If you have a look in the gallery you should find it's fairly easy to spot with experience - if you have trouble I can PhotoShop some pics for you :)

If you could put one of each next to each other, that would be good � only if it's no trouble, though! :)

Posted by jezlee on 27-07-2010 16:55

Sundew wrote:
See http://www.dipter...ad_id=8574 in our "Overviews"! The upper picture shows wing venation of Phasia.

Thanks for the link, sundew - the trick now is for me to remember this next time! :D