This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.
Entoman on Feb 26, 2013February 26th, 2013, 4:25 am EST
Isonychiids are tough for you guys. We've only got one out here to worry about. This specimen has the overall light color of rufa and the leg banding and prominent full length dorsal stripe of some forms of bicolor. The latter is my opinion. They are all so similar in this species group that there aren't any morphological characters (that I'm aware of) reliable enough to tell them apart in the nymph stage. Kondratieff came up with a few provisionally back in the 80's that were largely shot down a few years later by McCafferty. Depending on color and maculation patterns with species so variable (at least in this regard) is shaky diagnostic ground. :)
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
Crepuscular on Feb 26, 2013February 26th, 2013, 4:57 am EST
you know i don't think i do, but that Ameletus nymph had yellow trachea as well, and was collected from the same location. Diet? O2 levels? Neither the Heptageniids nor the Paralept had any yellow. I do see a yellow hue in the stripe sometimes though.