Mayfly for ID

[peterbolson]

I've been trying out the key in my new Naturalist's Handbook on Mayflies & wondered if anyone could confirm that this is Ecydyonurus sp., probably E.venosus ( the False March Dun )
For the record - It is about 15mm body length, 2 tails, hindwing present, non-turbinate compound eyes close together, base of forceps straight at tip, shape of penis, absence of dots & lines under abdo. ( some of these features not shown on photo ). These features would also fit with E.torrentis or dispar which apparently are almost impossible to distinguish.
Interestingly I earlier posted a photo of the E.venosus nymph which I had caught in the same beck.
Hope I'm not talking a load of rubbish again