• Category
  • Length Range
    22-43 µm
  • Width Range
    5.0-7.6 µm
  • Striae in 10 µm



Valves are dorsiventral. The dorsal margin is moderately arched, somewhat convex to nearly flat (or weakly concave in larger specimens) and subtly biundulate. The ventral margin is weakly concave to nearly flat. Apices are rostrate, broadly rounded and distinctly set off from the high dorsal ‘shoulders’. Terminal raphe ends are positioned on the ventral margin, some distance from the apices. Striae are weakly radiate, composed of fine areolae and nearly evenly spaced, although an occasional short stria may be interspersed along the dorsal margin. Under the SEM, the areolae can be seen to lie in separate depressions and number about 30 in 10 µm. Internally, the raphe fissure terminates in a raised helictoglossa.


Patrick and Reimer (1966) report Eunotia sudetica from acid to circumneutral waters in Pennsylvania and the southeastern United States. Siver et al. (2005) report this species from two acidic ponds on Cape Cod, Massachusetts. Lange-Bertalot et al. (2011) report that E. sudetica prefers small, running waters or wet bryophyte habitats. The one record of this species in the Montana Diatom Collection is from a lake high in the Sierra Nevada Mountains of California (photo below).

In Europe, E. sudetica is found in waters with a pH optimum of 5.0, specific conductance under 100 µm and tannic waters with high concentrations of fulvic acids (Alles et al. 1991). It was reported to be in waters with slightly elevated sulfate and aluminum concentrations.

Kings Canyon2008353
Credit: Trailspace.com
Evolution Lake at an elevation of 3,313 m in the Sierra Nevada Range of central California, home of Eunotia sudetica.

Original Description

  • Author
    O.Müll. 1898

Cite This Page

Bahls, L. (2013). Eunotia sudetica. In Diatoms of North America. Retrieved May 29, 2024, from https://diatoms.org/species/eunotia_sudetica


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Eunotia sudetica from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.