• Diatoma tenuis var. elongata : Lyngbye H.C. (1819)
• Diatoma elongatum var. tenue : (C.Agardh) Van Heurck
• Diatoma elongatum : (Lyngbye) C.Agardh (1824)

The cells are joined to each other by means of a gelatinous secretion at the corners of the cell, forming linear, zigzag or star-shaped colonies. The frustule is rectangular. In girdle view the valves appear rectangular or elongated with truncated extremities, while in valve view they are elliptical. The cells have a row of spines all along the edge of the valve. The cell contains numerous small chloroplasts.

Freshwater environments.

Distribution: as Diatoma elongatum var. tenue; in Europe: Romania (Caraus, 2002), Spain (Álvarez Cobelas and Estévez García, 1982); Australia and New Zealand: New South Wales (Day et al., 1995).

As Diatoma tenue: in Europe: Finland (Weckstrom & Juggins, 2006), Germany (Bahulikar & Kroth, 2007), Romania (Caraus, 2002), Spain (Ros, Marín-Murcia & Aboal, 2009). in South-west Asia: Iran (Jamaloo et al., 2006), China (Hu and Wei, 2006).

As Diatoma elongatum in Europe: Romania (Caraus 2002), Spain (Aboal, Prefasi & Asencio 1996); in Australia and New Zealand: New South Wales (Day et al., 1995), Tasmania (Day et al., 1995)

The algae of Romania., Studii si Cercetari, Universitatea Bacau, Biologie 7, Caraus I., 2002, 1-694

Biodiversity of diatom assemblages in a Mediterranean semiarid stream: implications for conservation., Marine and Freshwater Research 60:, Ros M.D., Marín-Murcia J.P., Aboal M., 2009, 14-24

Bibliographic check-list of non-marine algae in Australia., Flora of Australia Supplementary Series 4, Day S.A., Wickham R.P., Entwisle T.J., Tyler P.A., 1995, 1-276

Coastal diatom-environment relationships from the Gulf of Finland, Baltic Sea ., Journal of Phycology 42:, Weckstrom K., Juggins S., 2006, 21-35.

Algarum decas prima., Lundæ: Litteris Berlingianis, Agardh C.A., 1812, 1-14

Localization of EPS components secreted by freshwater diatoms using differential staining with fluorophore-conjugated lectins and other fluorochromes., European Journal of Phycology 42(2):, Bahulikar R.A., Kroth P.G., 2007, 199-208, 22 figs, 2 tables

The aquatic microphytes and macrophytes of the Trasvase Tajo-Segura irrigation systems, southeastern Spain., Hydrobiologia 340:, Aboal M., Prefasi M., Asencio A.D., 1996, 101-107

Study of diatoms flora in Jajrood river., Sciences and Technology of Environment 26, Jamaloo F., Falahian F., Nejadsatari T., Majd, 2006, 98-112.

The freshwater algae of China. Systematics, taxonomy and ecology, China: www.sciencep.com., Hu H., Wei Y., 2006, 1-1023

Catálogo de las algas continentales españolas., I. Diatomophyceae Rabenhorst 1864. Lazaroa 4:, Álvarez Cobelas M., Estévez García A., 1982, 269-285