Home / Diatoms / Pennate / Biraphes / Colonies / Eunotia
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Name derivation:
Greek Eu meaning good; notia meaning wet or moist.
Classification:
Eunotia Ehrenberg 1837. Order Eunotiales; Family Eunotiaceae One species, E. hemicyclus, is also classified as Semiorbis hemicyclus but this synonym is recommended to be retired (Morrow et al. 1981). Synonyms in PhycoKey: Amphicampa Ehrenberg, Desmogonium Ehrenberg, Pseudonitzschia (Cleve) H. Peragallo.
Morphology:
Colonial "ribbon" of rectangular cells as seen in girdle view, glued valve-face to valve-face. The valve view reveals a ridged convex edge and a smooth curved concave edge. Cells save terminal nodules bue no central nodules. The concave side of the valve is not swollen in the center. The raphe is so short as to be overlooked, and is located near both ends of each valve, with an extensive interruption separating the two raphe ends.
Similar genera:
Pseudoeunotia is not separated from Eunotia in PhycoKey. Fragilaria is a similar colonial "ribbon" with cells that taper toward both ends leaving a wedge-shaped space between each cell. Some species of the two genera appear to be intermediate between rectangular and tapered.
Habitat:
Approximately 30 freshwater species found in the United States. Found in deep brown waters in the summer. Some species of Eunotia can be inhibited by high light.
References:
Ehrenberg, C.G. 1837. Über ein aus fossilen Infusorien bestehendes, 1832 zu Brod verbacknes Bergmehl von den Grenzen Lapplands in Schweden. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königl. Preuß. Akademie der Wissenschaften zu Berlin 1837: 43-45. Heiden, H. and R.W. Kolbe 1928. Die marinen Diatomeen der Deutschen Südpolar-Expedition 1901-1903. Deutsche Südpolar Expedition 8 (Botany): 447-715. Morrow, A.C., T.R. Deason and D. Clayton  1981. A new species of the diatom genus Eunotia. J. Phycol 17(3):265-270.