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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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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Creno
Grants Pass, OR

Posts: 302
Creno on Aug 5, 2019August 5th, 2019, 3:37 pm EDT
Just getting back to the PC and a good look at your above pics. I don't think this is Gumaga. From what I can see it lacks the divided mesonotum and the metanotal sclerites are the wrong shape/size for Gumaga. The fact that you couldn't see the antennae makes me think they are right next to the eye. The rest of the characters also suggest this is one of the Lepidostoma and the case suggests pluviale group, which are very common in that part of the world.
Troutnut
Troutnut's profile picture
Administrator
Bellevue, WA

Posts: 2758
Troutnut on Aug 6, 2019August 6th, 2019, 4:10 am EDT
Thanks Dave. I'll move it there.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

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