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Dark Tan Spinners

Scientific Name
MatchScientific Name
**Rhithrogena hageni

This common name refers to only one species.

Mayfly Species Rhithrogena hageni

These are sometimes called Dark Tan Spinners.
According to Fred Arbona in Mayflies, the Angler, and the Trout, this is an excellent hatch and one of the most common fast-water mayflies in the West.
Rhithrogena hageni (Western Black Quill) Mayfly NymphRhithrogena hageni (Western Black Quill) Mayfly Nymph View 9 PicturesI'm basing the ID of this near-mature nymph on a male spinner with similar size and markings, collected on the same trip. There isn't a key to reliably identify the nymphs of most Rhithrogena species otherwise.
Collected July 4, 2020 from in
Added to Troutnut.com by on July 12, 2020
Female Rhithrogena hageni (Western Black Quill) Mayfly DunFemale Rhithrogena hageni (Western Black Quill) Mayfly Dun View 7 PicturesI was surprised by the olive cast on the body of this female Rhithrogena dun, which led me to mistake it for a western green drake (Drunella) in the field. I was pleasantly surprised to get a closer look and find something I hadn't collected yet. Its species ID is based on proximity to male spinner collected on the same trip, as well as physical similarity (size, tergite (
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.
)
coloration, dark streaks on the femora (
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
The femur of this Isonychia bicolor mayfly spinner is highlighted in red.
Femur: The main segment of an insect's leg close to the body, in between the tibia and the trochanter.
)
) to that specimen.
Collected July 4, 2020 from in
Added to Troutnut.com by on July 12, 2020
Male Rhithrogena hageni (Western Black Quill) Mayfly SpinnerMale Rhithrogena hageni (Western Black Quill) Mayfly Spinner View 14 PicturesAlthough I could not find the preserved specimen to examine under my good new microscope, I'm tentatively calling it one Rhithrogena hageni, based on apparent similarity to this specimen, which I was able to positively ID.

The relative angle of the penes (Penes: The paired genital structures of most male insects, which vary widely in form and are one of the main characteristics used for species identification.) is a bit shallower in this specimen, but I photographed another specimen from the same collecting trip (and I think even the same swarm, although I don't recall for sure) as the other one, and it had the shallower angle seen on this specimen. I'm guessing it's just variation within the species.
Collected July 8, 2019 from in
Added to Troutnut.com by on July 18, 2019
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