Stauroneis fluminopsis may be distinguished from S. fluminea by its wider valves, narrower stauros, less steeply radiate striae, and more widely spaced striae and areolae. Stauroneis fluminopsis differs from S. respectabilis by its somewhat smaller size and more linear valve shape. Stauroneis amphicephala is smaller and has more distinctly protracted ends and a wider, more marginally expanded stauros.