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.
Described by James, A.M. (1974) Four new species of stoneflies in North America (Plecoptera). Annals of the Entomological Society of America 67, 964–966.