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.

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Neoleptophlebia Mayfly Nymph Neoleptophlebia Mayfly Nymph

Dorsal view of a Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington

Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.

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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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Ephemerella tibialis

Male Serratella micheneri (Little Dark Hendrickson) Mayfly Nymph

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Dorsal view of a Male Serratella micheneri (Ephemerellidae) (Little Dark Hendrickson) Mayfly Nymph from Mystery Creek #199 in Washington

This specimen has tarsal claws with 7 denticles and tubercles on abdominal segments 4-7 only. It keys to Serratella micheneri, as do some other specimens from the same collection that lacked the dorsal stripe.

Collected July 27, 2019 from Mystery Creek #199 in Washington

Added by Troutnut on July 30, 2019

Collected July 27, 2019 from Mystery Creek #199 in Washington and added by Troutnut on July 30, 2019

Millcreek
Healdsburg, CA

Posts: 344

Millcreek on Dec 24, 2019December 24th, 2019, 2:31 pm EST

This nymph appears to be Ephemerella tibialis formerly known as Serratella tibialis. Check out Allen and Edmunds; http://www.ephemeroptera-galactica.com/pubs/pub_a/puballenr1963p583.pdf

Also check https://bugguide.net/node/view/696565/bgpage and https://bugguide.net/node/view/876178

Edit: Just noticed the other two Serratella micheneri sets of photos. These also appear to be Ephemerella tibialis.

Also spotted these two sets of photos where you identified the same or a similar nymph as Ephemerella tibialis.

http://www.troutnut.com/specimen/1176

http://www.troutnut.com/specimen/1178

"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Dec 25, 2019December 25th, 2019, 3:19 pm EST

I keyed this one under the microscope using a more recent key than Allen and Edmunds:

Jacobus, L. M., N. A. Wiersema and J. M. Webb. 2014. Identification of Far Northern and Western North American mayfly larvae (Insecta: Ephemeroptera), north of Mexico. Joint Aquatic Science meeting, Portland, OR. 176 pp. + suppl. Unpublished workshop manual.

The couplet on page 64 distinguishes E. tibialis from the other species:

81e) Maxillary canines strongly serrate laterally; thoracic nota with small, brown excrescences (sometimes difficult to detect), especially between forewingpads = Ephemerella (Vittapallia) tibialis (very similar to E. nuda)
81eâ€™)

Maxillary canines not obviously serrate laterally; thoracic nota without small, brown excrescences = 81f

If I'm remembering correctly (and I might not be), I looked pretty hard at the maxillary canines and the thoracic nota under the microscope and couldn't find the characteristics pointing to tibialis. It is a bit odd that I didn't mention that in the captions, though, so perhaps I'm misremembering or I just failed to interpret the characteristics correctly.

The key does describe Serratella as having "Abdominal terga either without tubercles or with relatively large, blunt and somewhat sinuate tubercles", and one of the other specimens I labeled as micheneri seems to have sharper tubercles than those shown in the corresponding illustration in the key.

Perhaps Luke can weigh in?

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Millcreek
Healdsburg, CA

Posts: 344

Millcreek on Dec 26, 2019December 26th, 2019, 3:01 am EST

Found these pictures at Bold. They're not very good quality but may give enough to identify the critters.

http://v3.boldsystems.org/index.php/Public_SearchTerms?query=%22Serratella%20micheneri%22[tax]

http://v3.boldsystems.org/index.php/Public_SearchTerms?query=%22Ephemerella%20tibialis%22[tax]

It would be nice to hear from Luke.

"If we knew what it was we were doing, it would not be called research, would it?"
-Albert Einstein