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> > Bitterroot river April mayfly nymph ?

Leskorcala has attached these 2 pictures to aid in identification. The message is below.
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LeskorcalaApril 7th, 2020, 7:41 pm
Posts: 16Love to pick few brains to ID this black and white mayfly nymph I just collected one on Bitterroot river in Montana April 7th I found it under tree trunk
MillcreekApril 8th, 2020, 9:28 am
Healdsburg, CA

Posts: 356
Definitely a member of Heptageniidae. Might be a Rhithrogena. If you still have the specimen, put it on it's back and see if the gills form a "suction cup", or if they meet in front and back, like in this picture.
LeskorcalaApril 8th, 2020, 9:08 pm
Posts: 16Thank you for your help fortunately i did not collect the specimen, i will try next time out.Very different in black and white or cream markings which i have not seen often.
MillcreekApril 8th, 2020, 9:25 pm
Healdsburg, CA

Posts: 356
I'm guessing at Rhithrogena. Seems likely because of the general aspect of it. The color is unusual for Rhithrogena but there are several undescribed species of western Rhithrogena nymphs.
KonchuApril 10th, 2020, 10:50 am
Site Editor

Posts: 505
That looks like my search image of a living Rhithrogena. I'm only aware of R. undulata having been found in the Bitterroot R in MT, but like Millcreek said, we don't know as much about the nymphs as we'd like. The record I have was from a June emergence, FWIW.

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