Isogenoides hansoni Stonefly Nymph Pictures

Jason-

Not to despair; this is what American Stoneflies: A Photographic Guide to the Plecoptera by Bill P. Stark, Stanley W. Szezytko, and C. Ridley Nelson has to say about genus Arcynopteryx:

"This genus is represented in North America by A. compacta (McLachlan). This species ranges from Alaska to Maine and has been reported as far south as Colorado. Males usually have shortened wings and are easily recognized by the long, lash-like epiproct tip. Females and nymphs are quite similar to Skwala. A. compacta has been collected around alpine lakes in the northern Rocky Mountains. No photographs are available for this group."

Also, Arcynopteryx compacta is listed by Stark/Baumann as residing in New York.

I believe that this is actually Isogenoides hansoni. When Dr. Chandler and Luke Myers made earlier "Cultus" comments on this specimen, they seem to have missed the prominent submental gills shown in photo #5 (and #7).

In addition to the submental gills (more than 2X as long as wide), the pale area on the 10th tergum, the distinct enclosed pale "M" mark on the head, and (often) the elongated pale spot in the center of the head are a few of the distinctive traits of this species. A complete description and a depiction of the dorsal habitus (figure #88) can be found in Sandberg and Stewart (Holomorphology and Systematics of the Stonefly Genus Isogeniodes, 2005).

The type specimens of I. hansoni were collected from my old homewaters on the Brodheads in 1937 by Preston Jennings (the author of the classic A Book of Trout Flies).

Cultus verticalis is a smaller, pale yellowish nymph, typically with a bolder, simpler dorsal pattern and less intricate markings on the dorsal surface of the head/thorax.

Hello gentlemen,

Again I come to you for guidance...

While monkeying around today in the aquarium, I flipped over a rock and this guy came scurrying out. I have recently been studying A. capitata and realized immediately that this might be a different species. Until now, I had thought that A. capitata was the only "golden stone" I had collected here in WNY to date, however I guess now I have one more under my belt! Is it weird that this excites me??

When I do my collecting on the stream and bring the insects home, I attempt to snap a pic of each before I place them in the aquarium, sort of a photographic inventory. This guy must have been hiding somewhere and was overlooked in that process.

So, anyone want to go out on a limb and confirm this as Cultus verticalis? Other than a measured length of 19mm, I can't really offer up any identifying features that aren't visible in the pictures. I don't have access to the M&C key. Anyone know if its posted online? I'll search my school library in a moment.

If it is C. verticalis, I've noticed that neither genus or species appear on the USGS Stoneflies of New York list. I see that Jason originally coded his specimen to the genus Arcynopteryx which contains three species. Again, none appear anywhere near WNY on the USGS list. Any other ideas of a possible alternative ID? http://www.npwrc.usgs.gov/resource/distr/insects/sfly/ny/toc.htm

If its not on the list, anyone know if and how I can submit my findings? Also, what is your experience with the USGS lists in regards to its accuracy and completeness? This and other instances have me thinking there are some holes in the data.

Unfortunately, this specimen perished as I was photographing it. I was hoping it would survive so that it might emerge and I could get snap photos as an adult. Tomorrow I'm heading to the location where I collected him to see if I can determine abundance in relation to A. capitata, as obviously the share the same lotic environment.

Thanks in advance!


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This stonefly comes from a fertile, cold small stream in the Catskills. I tried to ID it using the key to genera in Merritt & Cummins but I ended up with a fairly confident identification that can't be correct: Arcynopteryx, a western mountain genus. So I'm stuck at couplet 89 in the M&C key.