Frustules biraphid, asymmetrical to transapical axis, symmetrical to apical axis, wedge-shaped, with septa and pseudosepta visible in girdle view. A single stigma usually present on one side of the central area. Longitudinal lines lacking. Species in this region have striae that are usually punctate, not costa-like.
Light Microscope Image(s)
Each image is accompanied by the genus and species, California Academy of Sciences slide number (ie. CAS 612010), location of the specimen on the slide, and dimension in microns.