• Asterionella gracillima var. formosa : (Hassall) Wislouch (1921)

This is a colony-forming species, with the cells joined to each other at the apex, forming circular or spiral structures. In valve view the frustule is elongated with a broad apical extremity, while the central area may be slightly swollen. There is more than one chloroplast per cell.

Marine and freshwaters.

Distribution: in Europe: Finland (Weckstrom & Juggins, 2006), Romania (Caraus, 2002), Spain (Aboal, Prefasi & Asencio, 1996), Netherlands (Dijkman & Kromkamp, 2007); in North America: Ontario (Xenopoulos & Frost, 2003); in South-west Asia: Iran (Ramzannejad Ghadi, 2008); in Asia: Mongolia (Edlund et al., 2003); in Australia and New Zealand: New South Wales (Day et al., 1995), New Zealand (Flöder & Burns, 2005), Tasmania (Day et al., 1995), Victoria (Day et al., 1995); in the Pacific Ocean: Hawaiian Islands (Sherwood, 2004).

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

Photosynthetic characteristics of the phytoplankton in the Scheldt estuary: community and single-cell fluorescence measurements., European Journal of Phycology 41:, Dijkman N.A., Kromkamp J.C., 2007, 425-434.

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

The Diatomaceae in the water supplied to the inhabitants of London and the suburban districts. A microscopic examination of the water., , Hassall A.H., 1850, 1-60,

UV radiation, phosphorus, and their combined effects on the taxonomic composition of phytoplankton in a boreal lake., Journal of Phycology 39:, Xenopoulos M.A., Frost P.C., 2003, 291-302

New Records of Phytoplanktons of Gorgan Bay (southeast of Caspian Sea)., , Ramzannejad Ghadi R., 2008,

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

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

Checklist of Baltic Sea Phytoplankton Species. Baltic Sea Environment Proceedings No. 95, Helsinki Commission Baltic Marine Environment Protection Commission, Hällfors G., 2004,

The planktonic diatom diversity of ancient Lake Hovsgol, Mongolia., Phycologia 42:, Edlund M.B., Williams R.M., Soninkhishig N., 2003, 232-260

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

Bibliographic checklist of the nonmarine algae of the Hawaiian Islands. Records of the Hawaii Biological Survey for 2003, Bishop Museum Occasional Papers 80, Sherwood A.R., 2004, 1-26