Hex Mayflies
Hexagenia limbata
The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
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This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
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Mayfly Genus Neoleptophlebia
This genus was created somewhat recently from species, including some important to anglers, that were formerly grouped in Paraleptophlebia.
Genus Range
Specimens of the Mayfly Genus Neoleptophlebia
3 Male Duns
This is either Neoleptophlebia or Paraleptophlebia; I know of no way to be sure from a female dun alone. The genus is only a guess based on the fact that I found more Neoleptophlebia nymphs in the general area.
2 Female Duns
I'm just guessing Neoleptophlebia on this one. It could easily be Paraleptophlebia.
I'm just guessing Neoleptophlebia instead of Paraleptophlebia on this one because I tended to find more of their nymphs in the area, but take that with a grain of salt.
8 Male Spinners
I keyed this one out to species on the microscope because it was too small for the genitalia to show the distinguishing characteristics in the images here.
Based on the pale longitudinal forewing veins (excepting the costals), dark middle terga, and genitalia (Burks '53), this specimen is P. adoptiva.
I wasn't actually fishing the river where I caught this one. I was just scouting, didn't like the look of the water, and as I was walking back to the car this little dun landed on my vest. Why can't they all be so easy to collect?
12 Nymphs
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.
This specimen keys to the Neoleptophlebia memorialis group, which means it could be Neoleptophlebia memorialis or Neoleptophlebia temporalis. In the absence of a clear species key, I'm just guessing memorialis for now.
This nymph keys pretty well to Neoleptophlebia. Under the microscope, the fork on the first gill is more symmetrical than it looks in the picture here. Following the species key in Jacobus et al. (2014), the lack of tusks on the head or postero-lateral spines on segment 8 leads to adoptiva or heteronea, but both refer to a 3-segmented labial palp as a key characteristic, and this one only seems to have two segments, just like another, different-looking specimen from the same sample. So I'm stuck.
I thought the end of the abdomen of this one was damaged during capture and transport, but I photographed it anyway because it looked different from the others. However, it became clear under the microscope that it was actually just mid-way through molting and the abdomen was intact underneath. I got a couple nice microscope photos showing that. The pattern of markings on the abdomen is still distinctive compared to the other specimen, which was more representative of a common nymph in my sample. This one was unique.
I thought the end of the abdomen of this one was damaged during capture and transport, but I photographed it anyway because it looked different from the others. However, it became clear under the microscope that it was actually just mid-way through molting and the abdomen was intact underneath. I got a couple nice microscope photos showing that. The pattern of markings on the abdomen is still distinctive compared to the other specimen, which was more representative of a common nymph in my sample. This one was unique.
Looking at this one under the microscope, I noted that is has untracheated gills which fork 1/3 of the way from the base and postero-lateral spines on abdominal segment 9
This one is missing several gills due to capture damage.
1 Streamside Picture of Neoleptophlebia Mayflies:
After I took this photo, this specimen was swept out of this tiny pool into a riffle downstream, where I swooped it up with my aquarium net and brought it home to photograph. See it up close here.
In this picture: Mayfly Species Neoleptophlebia adoptiva (Blue Quill).
Start a Discussion of Neoleptophlebia
References
- Jacobus, L. M., Wiersema, N.A., and Webb, J.M. 2014. Identification of Far Northern and Western North American Mayfly Larvae (Insecta: Ephemeroptera), North of Mexico; Version 2. Joint Aquatic Science meeting, Portland, OR. Unpublished workshop manual. 1-176.
