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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Rhithrogena impersonata (Dark Red Quill) Mayfly Nymph Pictures

This was the only Rhithrogena specimen in a large sample of nymphs from a small Catskill stream. It looks virtually identical to Rhithrogena impersonata specimens collected in the Midwest, but I didn't get to check the distinguishing features under a microscope.

Ruler view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York The smallest ruler marks are 1 mm.
Ventral view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
This picture shows the characteristic gill structure of the Rhithrogena genus more clearly than the mature specimens of Rhithrogena impersonata that I collected back in the Midwest.  The "suction cup" gill structure is an adaptation to help the nymphs cling tight to rocks in fast water.

Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York
Dorsal view of a Rhithrogena impersonata (Heptageniidae) (Dark Red Quill) Mayfly Nymph from Mongaup Creek in New York

This mayfly was collected from Mongaup Creek in New York on April 19th, 2006 and added to Troutnut.com by Troutnut on April 21st, 2006.

Discussions of this Nymph

identification needed
2 replies
Posted by Kinza on Feb 4, 2017
Last reply on Feb 6, 2017 by Crepuscular
Can you please identify the genus of Family Heptagenedae if I send you images?

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Rhithrogena impersonata (Dark Red Quill) Mayfly Nymph Pictures

Collection details
Location: Mongaup Creek, New York
Date: April 19th, 2006
Added to site: April 21st, 2006
Author: Troutnut
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