Thread subject: Diptera.info :: Gonia.
Posted by Nikita Vikhrev on 25-04-2006 22:22
#1
Moscow region, 25 apr, on Tussilago, 12mm.
Thank to previos acquaintance with Gonia vacua, it seems to me that I can go directly to key for Gonia genera in this case. Not vacua, not divisa.
Gonia foersteri? This fly marked in my key as "rare species".
Help, please.
Nikita
Posted by ChrisR on 26-04-2006 12:46
#2
It doesn't seem to have any yellow/orange marks on the abdomen so could it be
Gonia picea?
Posted by Nikita Vikhrev on 26-04-2006 13:39
#3
Hi Chris, nice to hear you.
No, no yellow/red on abdomen at all (only scutellum is "Phaonia stile" "red").
G. picea (= sicula, = fasciata)?
Well, I need some hour to go by Gonia key one more time.
Nikita
Posted by Nikita Vikhrev on 26-04-2006 14:14
#4
Hi again, Chris.
There is doubtful teza which divide directions to picea and foersteri.
But if I was forced to come to some solution I'd still choise G. foersteri as N1 and G.picea as N2 probable species.
Let's wait for Theo's oppinion?
Nikita
Posted by ChrisR on 26-04-2006 16:34
#5
Yup - definitely wait for Theo :)
I am unfamiliar with
foersteri because we don't have that species in the UK. In fact it is very frustrating because I have never seen a
Gonia sp. in the wild and people keep telling me they have seen them locally to me!! :o
Cheers, Chris R. B)
Posted by Nikita Vikhrev on 26-04-2006 17:05
#6
Come Moscow!
Posted by Zeegers on 28-04-2006 08:12
#7
As you have noticed, I took my time.
Needed to check a few things.
And with good reason!
So here it is:
* the head is definitely yellow-orange, which makes as spring species only divisa and foersteri possible.
* the pollinosity on the abdomen, sharp narrow bands on tergites, is remarkable like divisa !
* there are orange spots on the abdomen, though small.
It turns out that foersteri doesn't have bands on pollinosity on the abdomen (Mesnil in Lindner).
So, if we are not tricked here by light and/of flash, this leaves only one conclusion:
it is a melanistic form of G. divisa.
True, I have never seen this, but melanistic forms are not that rare in G. ornata, for instance.
Of course, such abberant forms are very difficult to be recognized, so thinking about foersteri was actually quite natural
Theo
Posted by Nikita Vikhrev on 28-04-2006 09:19
#8
Realy, flies are much more interesting that any detective story! Realy, "the pollinosity on the abdomen, sharp narrow bands on tergites" - was the point not siutable for G. foersteri.
And if Theo himself has never seen melanistic form of G. divisa than my fly is even more rare than G. foersteri!
Thank you very much, Theo and Chris.
Nikita