Cymbopleura frustules are characteristically large and relatively broad in valve outline. The frustules of Cymbopleura are asymmetric to the apical axis, typically with a convex ventral margin and an even broader convex dorsal margin. The striae are composed of rounded areolae. The proximal raphe ends are expanded, while the terminal raphe fissures are hooked and dorsally deflected. Species within Cymbopleura lack apical porefields, therefore they do not produce mucilaginous stalks. Stigmata are absent. Cells grow as single individuals.
Species within Cymbopleura grow in benthic and epipelic habitats and include C. amphicephala, C. ehrenbergii, C. subcapitata, C. inaequalis, Cymbella lata, and the Cymbella heteropleura group.