• Category
  • Length Range
    31.4-38.4 µm
  • Width Range
    5.0-6.4 µm
  • Striae in 10 µm
    14-16 at mid-valve; up to 18 at valve ends



Valve outline is complex. The dorsal margin is convex and contains two prominent, pointed, widely-set undulations. Between these undulations, the dorsal margin may become less uniformly convex in smaller valves. The ventral margin is concave but becomes more linear in smaller specimens. The ventral margin also has subtle undulations where the valve is widest. Apices are capitate and dorsally recurved. Terminal raphe ends are visible near the apices. Striae are evenly spaced through most of the valve, becoming slightly denser at the apices. Areolae are dense and only barely visible with ideal illumination in LM.


Lange-Bertalot et al. (2011) suggest that this taxon is most often found in oligo- to dystrophic, moderately acid waters. The population imaged above was collected at Kings Lake Bog, a small, well-protected, oligotrophic, lowland sphagnum bog in the Puget Trough (Lebednik and del Moral 1976).

Original Description

  • Author
    Ehrenb. 1854

Original Images

Eunotia bactriana orig illus

Cite This Page

Bishop, I. (2016). Eunotia bactriana. In Diatoms of North America. Retrieved May 30, 2024, from https://diatoms.org/species/eunotia_bactriana


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Eunotia bactriana 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.