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Posted by neprisikiski on 12-03-2011 01:46

Hello, please hellp me in identification of the following specimen. Unfortunately, fly not in a good condition. It is male, collected in the begining of June. Thank you in advance.

Edited by neprisikiski on 12-03-2011 02:23

Posted by neprisikiski on 12-03-2011 01:47

Parafacial with setulae, outlined; eyes with setulae, but mostly damaged

Edited by neprisikiski on 12-03-2011 02:17

Posted by neprisikiski on 12-03-2011 01:48

Wing

Edited by neprisikiski on 12-03-2011 02:07

Posted by neprisikiski on 12-03-2011 01:48

Posterior part of the head with white hairs; prosternum hairy

Edited by neprisikiski on 12-03-2011 02:19

Posted by neprisikiski on 12-03-2011 01:49

Katepisternum with three setae and barette bare

Edited by neprisikiski on 12-03-2011 02:10

Posted by neprisikiski on 12-03-2011 01:49

Four anterodorsal setae on middle leg

Edited by neprisikiski on 12-03-2011 02:14

Posted by neprisikiski on 12-03-2011 01:56

Syntergite 1+2 hollowed to about the middle

Edited by neprisikiski on 12-03-2011 02:13

Posted by Zeegers on 12-03-2011 11:00

Hwoah, this is going to be though.

The arista is bare, is that correct ?

Theo

Posted by neprisikiski on 12-03-2011 16:34

I cannot see any hairs on arista; coxa is bare on posterodorsal surface as well. Note that the specimen is not in an optimal condition and something could be misleading.

Posted by Zeegers on 13-03-2011 09:29

#10

so, that was not easy at all.

I think it is Ptesiomyia alacris

Congratulations

Theo

Posted by neprisikiski on 13-03-2011 17:44

#11

Dear Theo,
I have Ptesiomyia alacris in my collection for a comparison, and it was my original identiication. The latter species have parafacial bare, and this is the main reason why I am looking for a truth. Is it possible, that hairy parafacial is not a stable character?

Posted by Zeegers on 13-03-2011 18:10

#12

I noted those hairs on the parafacial as well, though they are difficult to assess.

The combination of restricted excavation on syntergite 1, hairy prosternum, 4 post DC and distinct apical scutellar bristles is very unusual indeed. Database by Tschornsig gives only Ptesiomyia. The general head shape is OK as well.

I have 1 in my collection, I will check.

Theo

Posted by neprisikiski on 13-03-2011 18:18

#13

This specimen was collected in the same locality with other specimens, which I identified as Ptesiomyia alacris, but with clearly bare parafacial! So the locality is the same, but those hairs are obvious, though poorly visible on the photo...

Posted by Zeegers on 13-03-2011 21:16

#14

Mesnil (in Lindner) very clearly states that the parafacial is hairy on 'upper half' in Ptesiomyia alacris, and even more in other species of this genus.
This is little more than half, but given all the evidence I still think it is Ptesiomyia alacris.
The main question should be: what are these 'Ptesiomyia' with bare parafacials ? Those are the aberrant ones.

Theo

Posted by neprisikiski on 13-03-2011 21:42

#15

Well, please look to the specimen in a good condition, it has only a few setulae below the lowest frontal bristle.

Posted by Zeegers on 14-03-2011 07:53

#16

Thanks

The difference is not that large that is worries me.
Moreover, the first one is male (?) and the second one female, could be slightly sexual dimorph ?

Maybe someone should compare southern Ptesiomyia with northern, to check that those are really the same species. Wouldn't be the first time that there are actually 2 species.

That's all I can say, for the moment

Theo

Posted by ChrisR on 14-03-2011 09:16

#17

Very interesting find - I've never come across Ptesiomyia :)

Posted by neprisikiski on 14-03-2011 16:33

#18

Probably it cannot be nothing else than Ptesiomyia alacris (the same locality), I think that hairy parafacial is not a stable character and need correction in the key. Thank you for your discussion, Theo and Chris.