Thread subject: Diptera.info :: Syrphus or Epistrophe?

Posted by conopid on 04-04-2007 13:37
#1

This Syrphid is causing me problems! I cannot decide if it is Syrphus or Epistrophe. It certainly looks quite like a Syrphus, but I cannot see any long hairs on the surface of the calypter (squama), also it seems to be quite shiny on the dorsal surface of the thorax, and the yellow bands on tergites 2 - 4 seem quite deep compared to typical Syrphus.

Can anyone say whether this is Syrphus or not. If it is Epistrophe, is it E obscuripes?
:@

Edited by conopid on 04-04-2007 15:33

Posted by conopid on 04-04-2007 13:38
#2

Close up 1

Posted by conopid on 04-04-2007 13:39
#3

Close up 2

Posted by conopid on 04-04-2007 15:45
#4

Here is a better view of the abdomen with those yellow deep bars.

Posted by Gerard Pennards on 04-04-2007 23:48
#5

Epistrophe for sure, and I think this is a female of E. melanostoma.
However, there is a lot of variation in this genus, and there are atypical specimens which are very difficult to identify, so it is not a 110% ID! B)
Greetings,

Posted by conopid on 08-04-2007 22:29
#6

Gerrard,
I have had another long look at this fly and all it's tarsi are black. Do you think it might be Parasyrphus nigritarsis? Apparently it is sometimes confused with Epistrophe melanostoma, as they are similar looking flies?

Posted by Gerard Pennards on 08-04-2007 22:43
#7

Hi Nigel,
Well, yes, that would have been a possibility, since P. nigritarsis is the exception in the genus.
It has a yellow face (the others have a black facial stripe) and it's quite big, big enough to confuse it for a Syrphus or Epistrophe.
BUT....the female of nigritarsis should have straight yellow bands on the abdomen, more or less like Epistrophe grossulariae, look at (http://perso.orange.fr/cyrille.dussaix/Epistrophe_grossulariae/E.grossulariae_illus.html )
E. grossulariae has black antennae, nigritarsus has orange on the antennae.
So, you see why I didn't mention Parasyrphus nigritarsus, the stripes don't fit!
Greetings,

Posted by conopid on 08-04-2007 23:25
#8

Gerrard, many thanks for your further response. This is very interesting and this is a very awkward fly! It certainly cannot be a female Parasysyrphus nigritarsis if this species has straight yellow bands in the female. My specimen has a rather dark dusky antennal segment three. Not black, but not really orange either. It also has many black hairs on the scutellum. I am probably going to have to refer this one to the experts here in the UK.

Best wishes

Nigel Jones

Posted by Stephane Lebrun on 09-04-2007 10:15
#9

Hello Nigel,
did you check the anterior anepisternum for pilosity ?

Regards.

Posted by Dieter on 16-04-2007 01:38
#10

In my opinion this is a quite typical female of Parasyrphus nigritarsis. The entirely black tarsi of all legs work well to separate it from Epistrophe and Syrphus.

Best regards,
Dieter