References:
Krammer K. & Lange-Bertalot H. (1997): "Susswaserflora von Mitteleuropa", Vol.1, pg.102,103, Fig.31:8-14; Krammer K. & Lange-Bertalot H. (1997): "Susswaserflora von Mitteleuropa", Vol.4, Fig.64:1-8; Guide methodologique pour la mise en oeuvre de I'Indice biologique diatomees"(2000), Pl.34; Patric R. & Ch.W. Reimer (1966):"The diatoms of the United States", Vol.1, p.503; Pl.48, fig.3;
Description:
Valve is lanceolate with globose- to rostrate-capitate ends; axial area is narrow but slightly wider at the centre of the valve where it merges with a rounded, transverse central area that is often irregular in shape; striae are radiate throughout most of the valve, becoming parallel to slightly convergent at the ends; the nominate variety resembles N. rhynchocephala Kütz. Except for its smaller size and finer striation; length is 20-40µm, breadth is 5-7µm; striae count is 16-18 in 10µm
