Thread subject: Diptera.info :: Identification needed ...

Posted by AmpyxStark on 10-08-2022 17:43
#1

Dear colleagues, in 2012 I set some blue pan traps in an inland salt habitat in Saxony-Anhalt. The locality is Hecklingen. One trap operatet in an area, in which True Sedges were dominant. There occurs a tiny fly in big amounts (which is truly not belonging to my favorite families => Empidoidea). The fly is not larger than 2 mm and probably belongs to the Milichiidae. Is a determination possible by the appended picture? Thanks, Andreas

Posted by Jan Maca on 10-08-2022 18:46
#2

The fly is a chloropid (note e. g. lacking anal vein), subfmily Oscinellinaae. Like with your preferences, these flies re not my cup of tea...

Edited by Jan Maca on 11-08-2022 08:31

Posted by AmpyxStark on 11-08-2022 15:53
#3

Dear Jan, thanks for the remark! I was unsecure as there are prominant bristles on the frons ... Best regards, Andreas

Posted by von Tschirnhaus on 19-08-2022 17:10
#4

Chloropidae, Oscinellinae: Eribolus hungaricus Becker, 1910 [= Oscinella plana de Meijere, 1918)]. This tiny and narrow fly (small specimens measure only 2.0mm), possesses the typical wings of Oscinellinae; one or more orbital setae are longer than the remaining ones - different from the closely related genus Oscinella. In optimal lateral profile the best feature for the identfication of the genus is the flattened scutum (mesonotum) of all 8 Holarctic species. Only one genus in the high Andes of Venezuela [collected by me from behind dry cold-protecting leaves of an Asteraceae] has a similar depressed thorax! E. hungaricus has the frons completely dark. The dusted ocellar triangle ends distinctly before the anterior margin of the frons. The species is bound to reed beds (Phragmites australis), especially if growing on salty ground.

Edited by von Tschirnhaus on 22-11-2022 20:12

Posted by AmpyxStark on 19-08-2022 17:17
#5

Dear Michael, thanks a lot! Nevertheless: As I wrote to the determination of the family by J. Maca I was really unsecure to see a Chloropid-fly because of the rather long britles on frons, which are not only "hair-like" or so ... Okay - this might be a character, which is not actually used to separate Chloropids?

Posted by von Tschirnhaus on 19-08-2022 18:22
#6

dear Andreas,
there are so many exceptions to the worldwide published definitions for Chloropidae (3.054 valid spp). Long orbitals exist in several genera and in all Siphonellopsinae. Ocellar triangles may occupy the whole frons (e.g. Collessimyia nigricornis) or may be absent at all, there may be four long dorsocentrals and tiny flies (Alombus) without wings and halters. But all world Chloropidae possess a sharp edge on the propleuron, running from the fore-coxa upwards to the "humeral-callus", also Eribolus. Remove the head and you will detect this peculiar apomorphy (detected by Malloch) under high illumination.