Stonefly larva

Description:

Looks like a Perlidae although the abdomen is somewhat short for the Common Stoneflies usually found in my area. The unusual thing is the color - it it white (preserved in ethanol, darkened it up a bit). It really stood out in the sample. I can't find anything like it in my guides or online.

Habitat:

Fast clean streams, rocky bottom. (Perlidae pollution tolerance =1 and I had several positive ID's in the sample).