Salmonflies
Pteronarcys californica
The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
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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.
- 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.
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This one got a little bit damaged in the abdomen when I extracted it from its case. That's a delicate job.
Taxon on May 18, 2007May 18th, 2007, 10:04 am EDT
Based on the case, I would think Platycentropus. Can you see if it has prosternal horns extending beyond the head capsule to mentum of labium? See Merrit p. 375 Figure 18.191.
Troutnut on May 18, 2007May 18th, 2007, 11:25 am EDT
It doesn't. The prosternal horns only reach to the back of the head. It took about 10 minutes screwing around under a microscope to even see the prosternal horns (the whole thing is about half a centimeter long and the legs really wanted to be in the way). But I finally got a good view, and they are short, so that rules ot Platycentropus. The case seemed like a good match, though.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Troutnut and salmonid ecologist
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