Ninastrelnikovia guide
  1. Valves small, less than 25 µm
  2. Valves with strong central inflation
  3. Striae short, restricted to the valve margins
  4. Cells joined in band-like colonies

Valves are symmetric to the apical and transapical axis. Valves are small, typically less than 25 µm. The central margin is strongly inflated and the apices are broadly rounded. Striae are restricted to the valve margins. The raphe is filiform. The proximal raphe ends are relatively widely spaced. The distal raphe ends are straight or deflected to the same side. The axial area is variable, from narrow to moderatley broad.

Cells occur as solitary individuals or joined together in band-like colonies. Valves are joined face to face, and as a result, colonies are typically found in girdle view.

Because of the small size, valve shape and marginal striae, this taxon has been confused with small fragilarioid taxa, including Staurosira.

Navicula gibbosa Hustedt was originally descibed from Sumatra, Indonesia (Hustedt 1937). It has been reported from rock pools and temporary habitats across a wide geographic extent, including rivers in southeast (Patrick and Reimer 1966) and western North America. Lange-Bertalot and Fuhrmann (2014) reported populations in rock pools in Algeria and Namibia.