Moved from Hexagenia bilineata.

Hi Eric,

I would place this as Hexagenia rigida for these reasons:

1. The compound eyes are yellowish dorsally and are widely spaced. They appear to be separated by about the width of a compound eye. (Given the angle, this is a bit of a judgement call.) The eyes of bilineata are typically dark brown or black.

2. Although this is a somewhat pale specimen, relatively speaking, the dorsal abdominal markings are a very good match for the pattern depicted in Spieth 1945 (plate 4, fig. 25). In addition, the yellow middle and hind legs, and black-striped pronotum are not typical of bilineata.

3. If you enlarge the full-resolution image, you can see the right-hand male member alongside the clasper near the base of the tails. Although slightly out of focus, it is as expected for rigida. (It would be hooked or sharply curved in limbata or bilineata.)

Best,
Lloyd

Moved from Mayflies.

Hi Erik-

I believe this male subimago to be Hexagenia bilineata.

Moved from ID Request.

I think this is likely in the genus Hexagenia