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The Specimen

The Discussion

PeterOJune 6th, 2007, 7:58 am
Posts: 8Jason-

This is actually a specimen of Acroneuria abnormis. Paragnetina species have a complete set of spinules/setae on the occiput, which this guy is lacking. On a semi-related subject, could you forward me the collection data for the Arcynopteryx paralella you got from the Catskills? Thanks a bunch.
GONZOJune 6th, 2007, 8:15 am
Site Editor
"Bear Swamp," PA

Posts: 1681
Thanks, Peter. The ID mistake was mine, not Jason's. When he collected this specimen, I took a quick glance at it and assumed it was P. immarginata (which is one of the more common of the highly marked "golden stones" in the Poconos). When I returned to see his close-up pictures, I noticed the difference in the dorsal markings and realized I had made a hasty judgment.
TroutnutJune 6th, 2007, 8:28 am
Bellevue, WA

Posts: 2737
Thanks for the correction, Peter. I'll get you that Arcynopteryx info.

Gonzo, I guess I can forgive you... ;) Really, thanks for showing me to that collecting spot! I got the first Cinygmula nymph I've collected, so it was worth it for that, among other things.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
GONZOJune 6th, 2007, 8:59 am
Site Editor
"Bear Swamp," PA

Posts: 1681

The forgiveness is appreciated, although it also means that we failed to collect a P. immarginata specimen for your site. But, the Cinygmula was a revelation to me as well. And I'm still trying to figure out why we found mature D. lata (cornuta) nymphs two weeks before they normally emerge in that stretch. That little stream was abnormally low and warm, but I'm not sure that accounts for the difference.
HuckleberryOctober 1st, 2010, 8:02 am
Williamsburg, VA

Posts: 1
Hey guys,

I don't see a cercal fringe, even in the closeups. As you know, this is a key characteristic of Acroneuria, sp. Could it be blending in with the white background?

I'm not all that familiar with abnormis. Clue me in.

GONZOOctober 1st, 2010, 12:21 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Could it be blending in with the white background?

Yes. If you click on the full size view of photo #9, you can make out a fine faint fringe of long hairs along the inside edges of the cerci. In photo #5, the (whitish) fringe along the inside of the right cercus partially obscures part of the hook.

In general appearance, A. abnormis nymphs lack anal gill tufts and tend to have broadly concolorous (dark) tergites and femora instead of the narrower dark abdominal banding and leg bands often found in sympatric species like lycorias or carolinensis. The pale band across the back of the head also tends to be more narrowly linear.

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