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.
Brachycentrus is one of the most important caddisfly genera in America. Microsema is smaller and rarely, if ever, significant. Amiocentrus aspilus can be an important Western hatch.
That would indeed be nice, but I don't believe one exists. In my experience, genus names of caddisflies (as opposed to mayflies) are rarely used in spoken discussion among fly fishers, probably for that very reason. Incidentally, the only source (of which I'm aware) for the phonetic pronunciation of Ephemerella suggests it to be ef-fem-er-ella.