Basionym: Ceratoneis closterium Ehrenberg.
Solitary elongated cells with two chloroplasts. Spindle shaped middle part, with extended ends (rostra), partially twisted abouth the length axis. Raphe with central nodule and fibulae. Many narrow girdle bands.
Morphometrics: apical axis: 30-400 µm, transapical axis, 10-12 fibulae in 10 µm, 70-100 interstriae in 10 µm.
Distribution: Fjords and coastal waters of Norway,