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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.

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington
This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.
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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Female Siphlonurus occidentalis (Gray Drake) Mayfly Dun Pictures

I caught this specimen two days' walk from my macro lenses, but I don't think I have a dun of this species yet, so I took the best photos I could with my iPhone.

Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming
Ventral view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming
Lateral view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming
Dorsal view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Dun from Island Lake in Wyoming

This mayfly was collected from Island Lake in Wyoming on August 30th, 2020 and added to Troutnut.com by Troutnut on September 18th, 2020.


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Female Siphlonurus occidentalis (Gray Drake) Mayfly Dun Pictures

Collection details
Location: Island Lake, Wyoming
Date: August 30th, 2020
Added to site: September 18th, 2020
Author: Troutnut
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