Diploneis ovalis has larger central area and a higher striae density (12-14 in 10 µm). Diploneis krammeri also has higher striae density (11-12 in 10 µm). When found associated, the striae structure is the best guide to separate Diploneis krammeri from Diploneis elliptica (not the valve size). Diploneis austriaca has conopeum, visible only under SEM.