Mayfly ID

[creekx]

Encountered this mayfly hatch on a North Idaho stream. Sorry for the crap phone photo. I was on the oars and could not access my DSLR.

Some type of Heptageniidae clinger like Epeorus or Heptagenia? About a size 15, plain wings, large hind wings, two tails. It may have the dark, heart-shaped spot on the forelegs like Epeorus. Are the light, contrasting edges of the body segments a tell?

 

[Mark Melton]

I'm really not sure, with it being a subimago and not being able to tell the sex due to the picture being out of focus, but I'd guess Rhithrogena. Here's pictures of a female and male imago to compare.

Mayfly - Rhithrogena - BugGuide.Net

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net

mayfly - Rhithrogena flavianula - BugGuide.Net

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net

 

[creekx]

I'm really not sure, with it being a subimago and not being able to tell the sex due to the picture being out of focus, but I'd guess Rhithrogena. Here's pictures of a female and male imago to compare.

Mayfly - Rhithrogena - BugGuide.Net

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net

mayfly - Rhithrogena flavianula - BugGuide.Net

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net

It is a male - tough to see but has large eyes and clasper. Doesn't help that its the same color as my hat!

Don't rhithro wings typically have pronounced veining or a leaded-glass window appearance?

Correction about the heart-shaped spot on the forelegs like Epeorus - meant to say femur. It's barely distinguishable.

It looks a lot like this Epeorus pleuralis which is an Eastern species though:

 

[Mark Melton]

Rhithrogena wings may or may not have pronounced veining or a leaded-glass appearance. I've seen a fair number that are relatively clear with a minimal veining. All depends on the species I guess.
There don't seem to be many species of western Epeorus that have been photographed with the exception of the two most common ones, E. longimanus and E. albertae and those two are lighter in appearance than your mayfly. However there are several western species that haven't been photographed (at least not that I know of) and the descriptions depend heavily on the penes.

 

[jamma]

Hard to tell without a detailed close-up, which is usually the case, but I think Heptagenia fits better here. Check your sources and see if you don't agree.

 

[Mark Melton]

It's possible. Near as I can tell Idaho has three species of Heptagenia, H. elegantula, H.solitaria, and H. adaequata. I did find pictures of all three at Troutnut and Bugguide. However, none of them are of subimagos. Here are links to the photos. Don't think we'll be able to come to any conclusion without either a detailed photo of the penes or a specimen in hand.

Male Heptagenia adaequata Mayfly Spinner Pictures

2 close-up macro pictures of a Male Heptagenia adaequata Mayfly Spinner, collected from the Columbia River in Washington on July 22, 2012.

www.troutnut.com

Mayfly Species Heptagenia solitaria (Ginger Quill) hatch & pictures

Life cycle & behavior of the mayfly species Heptagenia solitaria (Ginger Quills), with 8 close-up macro pictures & hatch matching tips for fly fishing.

www.troutnut.com

Species Heptagenia elegantula - BugGuide.Net

An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information.

bugguide.net