|Option 1||Option 2|
|Pronotum anteriorly with erect submarginal setae widely spaced, especially mesally, and with some short, stout, marginal setae among fine marginal hairs (sf 19.328)||Pronotum anteriorly with submarginal setae more closely spaced, especially submesally, and all of similar length and thickness, without short, stout setae among fine marginal hairs (sf 19.329)|
|Abdominal tergum VII with a single long seta on either side of midline posterodorsally, sometimes each side with 1 or 2 much smaller setae (sf 19.330)||Abdominal tergum VII with 1–5 long setae on either side of midline posterodorsally (sf 19.331)|
|Lateral abdominal gills usually lacking from segment V, sometimes from IV or terminating with anterior position of segment IV||Lateral abdominal gills terminating with anterior portion of segment V|
|Case of final instar made of stout pieces of wood (sf 19.447) or of fine rock fragments (sf 19.448); cases of earlier instars made of pliable plant materials||Case of pieces of wood and bark (sf 19.449)|
3 Example Specimens
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
See the forum discussion for discussion with a caddis expert (Dave Ruiter / Creno) about the identification of this specimen. I'm a bit perplexed because some gills seem to have more than 4 branches, which would lead in a different direction at Couplet 18 of the Key to Genera of Limnephilidae Larvae, but Dave knew his stuff a lot better than I did. He was convinced this is Onocosmoecus. The current range maps would put this in Onocosmoecus unicolor as the only option, but he believed there are probably multiple not-yet-distinguished species under that umbrella and suggested keeping this one's ID at the genus level for that reason.
No further information about this genus is available on Troutnut.com at this time.