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Hello

I caught this fly 2 days ago in a alkaline fen. It is an Ogcodes and to know the species I tried to use Faunistik und Taxonomie der Acroceriden (Diptera) der Schweiz by M. Weinberg and G. Bächli.

I think I'm not wrong if I say it's a male. I mainly hesitate between O. gibbosus and O. zonatus but I think it is more likely to be the first species. I don't know if the halter is white enough for gibbosus and I'm not sure to well inderstand the part about "Schüppchenrand". But the legs color doesn't match with pallipes I think and the hind femora et tibias are too straigh for a male zonatus.

What do you think about this fly ? I can do other pictures of the fly if necessary.

Found in "Marais d'Episy", Moret-Loing-et-Orvane, Seine-et-Marne, Île-de-France, France
On the 2nd of July 2022
Body length : 6 mm

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Second picture :

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Third picture showing the calyter and the halter :

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Fouth picture showing a hind leg :

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Yes, I agree. Pallipes is much darker tergites. Yellow halter clearly supports gibbosus.

Well documented !

Theo

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Thank you very much Theo.