This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
I haven't seen the imitation of these things stressed, but in August 2003 on one of my favorite rivers the largest brown trout I kept had stomachs full of these things.