Sellaphora saugerresii

Valves are linear-elliptic to linear-lanceolate with rounded ends. The axial area is narrow and straight. The central area is wide, more or less symmetric, and bow-tie shaped with two or three shorter, uneven striae. Striae are slightly radiate near the central area, becoming very parallel toward the poles. Striae may be resolved under optimal lighting in LM. In SEM, striae are seen to be biseriate and become uniseriate toward the axial area. Areolae are not resolvable under LM, but under SEM are small and round. The raphe is straight with slightly curved, tear-drop-shaped proximal ends. Terminal raphe fissures are curved toward the same side of the valve. Polar bars are absent.

There has been much confusion regarding the taxonomic identity of Sellaphora saugerresii and related species. The recent treatment of the former Eolimna minima and Sellaphora seminulum species complexes are further explained in Wetzel et al. (2015), and the specimens examined here appear to agree with the treatment of S. saugerresii described by the authors. Note that, some years back Sellaphora saugerresii was described as a 'doubtful synonym' of Navicula seminulum by Krammer and Lange-Bertalot (1986, p. 230), but we consider that the Lange-Bertalot images do, indeed, show S. saugerresii.