Eunotia bilunaris is similar in shape and size, but has less arched, often clearly tapering valves with acutely rounded apices. Valves of E. naegelii are narrow from the center toward the apices, have a smaller width and higher stria density. Eunotia mucophila has a similar valve outline, but is usually less silicified, appears more delicate, has narrower valves, higher stria density and raphe ends that are difficult to see in LM. Eunotia juettnerae has clearly tapered valves from the center toward the apices. It is not thought to occur in North America. Eunotia cantonatii, so far observed only in Europe, is similar in shape, but possesses clearly tapered ends and a single, apical hollow protrusion (sometimes visible in LM).