#1
I found this chrysogaster monday in a swamp.
I think it could be Chrysogaster coemiteriorum or Chrysogaster virescens. Or Riponensia splendens?
Someone can help me?
Date: 16/08/21
Localisation: Saint Sulpice de Grimbouville (27), France
Posted by
Sundew on 28-08-2021 16:18
#2
This is tricky indeed! However, I would exclude
Riponnensia, because it has dark wing bases and two dust stripes on the thorax (see picture 2 and 3 in
https://diptera.i...d_id=22325). In
Chrysogaster the abdomen viewed from above has a dull top and T1 dull, whereas the tergites 2-4 have metallic edges, whereas in
Riponnensia all tergites have metallic edges - I tend to the former.
There are two species of Chrysogaster with a yellow wing base:
C. coemiteriorum and
C. basalis (
https://books.goo...&hl=de). So
C. virescens is no candidate. The face of
C. coemiteriorum is very broad, as wide or wider than the width of an eye, which fits your front view picture.
C. basalis has a narrower face (smaller than the width of an eye). I think I see also a dusted proepimeron, so I find
C. coemiteriorum quite probable.
A bit confusing ist the statement of Falk (
https://www.flick...610280227/) that the 3rd antennal segment of
C. coemiteriorum ist "usually dark", but the pinned animals of
C. coemiteriorum in
http://v3.boldsys...xid=384753 have clearly orange antennae.
And a last remark: here (
http://lists.nott...01556.html) we read that the correct spelling of the name is
C. cemiteriorum without the first "o".
That's what I found out! So I would label your pictures "
Chrysogaster cf.
cemiteriorum" - perhaps some Syrphidae expert will even delete the "cf.".
Regards, Sundew