The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
|Option 1||Option 2|
|Most gills with 2 or 3 branches, none with more than 4 ||At least some gills with more than 4 branches |
|Remaining genera: Allocosmoecus, Amphicosmoecus, Anabolia, Arctopora, Asynarchus, Clistoronia, Dicosmoecus, Eocosmoecus, Frenesia, Glyphopsyche, Grammotaulius, Halesochila, Limnephilus, Nemotaulius, Onocosmoecus, Philarctus, Platycentropus, and Sphagnophylax||Remaining genera: Crenophylax, Hesperophylax, Ironoquia, Lenarchus, and Psychoronia|
5 Example Specimens
This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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.
1 Example Specimen
|Go to Couplet 19||Go to Couplet 40|