I don't know how in Earth I gave this identification, years ago, to this very common mayfly in my zone. Maybe looking a book I've found one similar with this name. But unfortunately, there are any adult picture of Choroterpes in the web. Leptophlebiidae is sure, and females are very difficut to see, while the males (turbinate eyes) are very common into my city (Zaragoza, NE Spain). Posterior wings are very small, and costal zone very dark. Wingspan is about 15 mm. Two cerci.
The rivers of the zone are big, deep, contaminated and slow.
Thanks Konchu. Maybe it's a baetid, but due to elongate wings, turbinate eyes, posterior wings present... I thinked that was identical to Leptophlebiidae. Now I need a genus -and, if it's possible, species- level identification ;-)
Troutnut on Mar 11, 2008March 11th, 2008, 4:41 pm EDT
It looks like a Baetid to me, too. The features you listed aren't incompatible with that ID. As for species and genus, I doubt we can be of much help. Even a series of high-quality closeups like I've got on this site often isn't sufficient to figure out genus and species for Baetid mayflies, even well-known American species.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Not a lost answer, just a deleted answer. Taxon had just run across a photo of dun with a fore wing which was similar to the one in your photo, and impulsively posted a comment, but promptly changed his mind and deleted it. Incidentally, the photo was in the book Trout Fly Recognition by John Goddard, and the photo was labeled Leptophlebia vespertina female dun.