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> > Puzzled on this mayfly, not even confident on family
The Specimen
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.
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.
The Discussion
| Troutnut | July 23rd, 2019, 12:11 am | |
 Administrator Bellevue, WAPosts: 2737 | This seems to be some sort of Heptageniid, based on the two tails and five segments on the hind tarsus. Following the key in Merritt & Cummins seems to lead to Rhithrogena, but it doesn't fit a characteristic described in Needham's Biology of Mayflies for that genus: "Tibia of hind leg in both sexes about 1/4 length of femur." | |
| Jason Neuswanger, Ph.D. Troutnut and salmonid ecologist | ||
| Millcreek | July 23rd, 2019, 2:34 pm | |
| Healdsburg, CA Posts: 356 | For what it's worth, this seems to be Heptageniidae and Rhithrogena based on the wings and penes. Also, if you take a look at Bugguide the photos there don't show the hind tibia being 1/4 the length of the femur. https://bugguide.net/node/view/50753/bgimage?from=0 | |
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