#3
I agree with Tony, it is not even a Baetidae but a Heptagenidae with some similar genera. It is no Rhithrogena or Epeorus but something else, like Ecdyonurus as suggested by Tony. It may also be genera like Electrogena, Hetagenia or Kageronia, but I cannot decide. You can check with the key made by Eiseler (2005) on german mayfly nymphs for instance:
http://www.zoboda...1-0112.pdf