Thread subject: Diptera.info :: Stegana, with genitalia, N Sweden

Posted by viktor j nilsson on 05-03-2010 21:04
#1

Hi,
this Stegana sp. was one of a few found in a window trap set on dead old aspens. I have tried to ID it with Faun.Ent.Scand, but nothing really makes me feel complete comfortable.
My best guess would be Stegana coleoptrata, but the drawing of the genitalia in Faun Ent Scand shows a very large, swollen aedeagus, which doesn´t fit my specimen well. Also the halteres should be dark, while this fly has pale halteres.

The trap was one of several from outside Lycksele,. Northern Sweden, roughly at Lat: 64, Lon: 18.
June-July 2009

Posted by viktor j nilsson on 05-03-2010 21:10
#2

Genitalia posteriorly

Posted by viktor j nilsson on 05-03-2010 21:11
#3

...and laterally

Posted by viktor j nilsson on 05-03-2010 21:11
#4

...and finally ventrally. I hope this suffice.

Posted by viktor j nilsson on 05-03-2010 21:12
#5

...and finally ventrally. I hope this suffice.

Posted by Dmitry Gavryushin on 05-03-2010 21:47
#6

Stegana mehadiae Duda? (based mostly on form of claspers and colouration of legs/pleurae, Lastovka & Maca, 1982).

Posted by viktor j nilsson on 06-03-2010 02:41
#7

I think you are right, the wings are about 4 mm long, I actually initially ended up om S. mehadiae - I somehow thought the shape of the epandrium was wrong - it is said that the epandrium should be "remarkably expanded forwards dorsally", forwards in this case meaning to the upper left in the third picture. But that really is the only thing that doesn´t fit. Also the illustration of the claspers (if this means the surstyli?) are a bit off, the apex of the surstyli in Faun.Ent.Scand are more oval, while the fly above has more squarish apices. However, there are many (>15) rows of acrostichals and the frons is narrowing towards the front, which fits S. mehadiae but not much else.

So I agree that it is S. mehadiae - thank you Black.