I have recently been reading The Caddis and the Angler by Larry Solomon and Eric Leiser. On page 60 they describe a gill-ribbed larva. Here is my version.
I have tied several of these and plan to try them on the Spring River this Spring. The flies are easy to tie and imitate the Hydropsyche larva. My son and I have collected many of these larva on the Spring. The fly is tied on a size 14 hook with a grey-blue floss body with a rib of peacock herl palmered up the body. The herl is tied off and the remainder is used to form a thorax. The fly is finished with a thread head.