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> > Stuck on the family ID on this one -- any thoughts?

The Specimen

Plecoptera (Stoneflies) Stonefly AdultPlecoptera (Stoneflies) Insect Adult View 9 PicturesI'm puzzled on the family ID on this one. Just going by the size, shape, and color, it looks like Chloroperlidae. However, the key in Merritt & Commins has me puzzled. the second anal vein of the forewing is does not appear to be forked, and the apical (Apical: Close to the apex; tip or end.) tmaxillary palpal segment is about 60 % of the length of the penultimate segment, which does not strike me as "greatly reduced." If we assume it's not Chloroperlidae and move beyond there in the key, we get to the position of the cubitoanal crossvein (Crossvein: Short cross-wise veins in an insect wing which connect the long longitudinal (length-wise) veins.) relative to the anal cell in the forewing -- touching it in this case, which would indicate Perlidae. But the size and relatively skinny, cylindrical body really don't seem to match Perlidae at all.

If we assume it actually is Chloroperlidae and advance to couplet 92 (at least in the 5th edition key), we end up with one feature (vein Cu2 well developed with several intercubital crossveins (Crossvein: Short cross-wise veins in an insect wing which connect the long longitudinal (length-wise) veins.) connecting Cu1 and Cu2) contradicting two others (posterolateral margins of head usually parallel behind eyes, and epicranial sutures prominent) in the first couplet.

I'm clearly missing something.
Collected September 17, 2020 from the Yakima River in Washington
Added to Troutnut.com by on September 19, 2020

The Discussion

TroutnutSeptember 19th, 2020, 11:03 am
Administrator
Bellevue, WA

Posts: 2592
See the caption to this specimen for the reasons why I'm not sure what family to place it in. In a nutshell, it looks like Chloroperlidae, seems to key to Perlidae, and doesn't look like Perlidae at all. I'm either missing or misinterpreting some key features or stumbled upon a specimen that violates a bunch of "usually" characteristics in the key.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

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