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 collected this one by sweeping through leaves in vegetation near the stream, and I kept it thinking (in the fading light) that it might be one of the tiniest caddisflies. It is not.