Guide to Diatomella

The frustules of Diatomella are symmetrical to the apical and transapical axes. The valve outline is linear-elliptical. An internal septum is present, with three openings forming a distinctive internal thickening of silica. The striae are short, often not extending far beyond the valve margin. The proximal raphe ends are expanded.

Diatomella is the only naviculoid diatom that possesses a septum (rather than a pseudoseptum). A single species, D. balfouriana, grows in high elevation alpine regions of Colorado, Utah, and Wyoming. The taxon prefers aerophilic habitats low in nutrients.