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Thank you for your answer, Darwyn.

With that key, I think it's either C. leptogaster or C. nova, but I think it's difficult to say more with my pictures. I don't even know if it is a male or a female. But I can see that humeri are partly orange and that the orange spot on the front is quite extensive and almost connected to the vertex (as said in this description), so it is maybe closer to C. nova ?