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Troutnut Forum > Specimen Discussion > I'm pretty unsure about these IDs

The Specimen

Attenella attenuata (Small Eastern Blue-Winged Olive) Mayfly SpinnerAttenella attenuata (Small Eastern Blue-Winged Olive) Mayfly SpinnerView 11 Pictures
Region: Upper Midwest
Collected Jul 1, 2005
Added Apr 22, 2006

The Discussion

TroutnutJuly 4th, 2006, 5:13 pm
Fairbanks, AK

Posts: 1115
I wish I had been able to get a male spinner for a positive ID. I wasn't able to collect any, unfortunately. The keys I have to the adult genera of the Ephemerellidae require one.

I've placed several specimens collected from a similar emergence on nearby rivers into the species Attenella attenuata, because they look exactly like the picture of that species in some books, most recently Ted Fauceglia's Mayflies. They are handy midday and early evening emergers in northwest Wisconsin at a time when not much else is on the water. But I'm not convinced that the identification is correct.

For one thing, although I tried sampling several times in stretches where the duns were emerging, the only mature Ephemerellid nymphs I found keyed out to Ephemerella inermis, which is now Ephemerella excrucians. These adults fit the general description for that widely variable species. I never found any Attenella nymphs.

I suspect they are the same species referred to in nearby parts of Wisconsin as "Kinni Sulphurs" and "Booger Sulphurs." As best I can tell from looking up those names, they seem to have been identified as Ephemerella inermis but there is a local belief that they are Ephemerella needhami, even though their color does not at all fit the description for that species.

Ah, to have a male spinner under the microscope...
Jason Neuswanger
The Troutnut
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Replies:
TaxonJuly 6th, 2006, 2:00 am
Mercer Island, WA

Posts: 485
Jason-

Don't see anything that would cause me to doubt that she's an Attenella imago. However, I'm curious why you are thinking A. attenuata, rather than A. margarita, given the olive abdomen.

In any event, I've heard you refer to Ted Fauceglia's book one too many times now. Guess I'm just going to have to give up and go buy one!
Roger Rohrbeck
www.FlyfishingEntomology.com
TroutnutJuly 6th, 2006, 11:07 am
Fairbanks, AK

Posts: 1115
Fauceglia's book has some really great pictures, and they're the main reason I'd recommend buying it. They're the best I've seen in publication. They are accompanied by entomological information, but except for a few passages it's just material combined from other other major sources.

I haven't thought about whether it might be margarita or not, but attenuata is generally considered to be the most common eastern species.

I'm doubtful of the genus identification for a few reasons:

1. Attenella has a history of confusing people and getting credit for other hatches (like the eastern Drunella BWOs).

2. I couldn't find any Attenella nymphs, but I did find mature Ephemerella excrucians nymphs (keyed to synonymous inermis).

3. I know people who recognize the mayfly as a hatch called the "Kinni Sulphur" on a nearby river, which has been tentatively identified as E. inermis.

The main thing suggesting that it's attenuata is that it's a perfect match to published pictures of that species.
Jason Neuswanger
The Troutnut
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