The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
I looked at this nymph closely under a microscope to ascertain some key features I was wondering about in previous photographs of similar specimens. It definitely does have the fan-tail characteristic of the Ephemerella genus. It also has strongly 2-banded tibiae and definite tiny abdominal tubercles.
This mayfly was collected from unknown in Wisconsin on February 7th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.