Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is slightly expanded. Valves are 39-75 μm long by 17-23 μm wide, as reported by Krammer (1997). The valve apices are rounded. The axial area is relatively broad in the central part, narrowing at the valve ends. The raphe branches are lateral and have a slight arch towards the ventral margin. Each raphe branch is positioned nearly centrally within the axial area. Proximal raphe ends are slightly expanded and dorsally deflected. Distal raphe ends curve slightly to the dorsal margin, but are deflected ventrally near the valve apices. The dorsal striae are divergent. The rows of external dorsal areolae closest to the central area are oval, to irregular and become lineolate. Central dorsal striae 10-11 in 10 μm and distal striae 5 in 5 μm. Central ventral striae 7-8 in 10 μm, and distal striae 6 in 5 μm. The density of areolae within a central, dorsal stria is 8 in 5 μm. The striae continue on the dorsal valve margin.


Original Description

  • Author
    Krammer 1997
  • Length Range
    39-75 µm
  • Width
    16.8-23 µm
  • Striae in 10µm

Original Images

Encyonema yellowstonianum orig illus
Encyonema Yellowstonianum Orig Text

Cite This Page

Spaulding, S. (2010). Encyonema yellowstonianum. In Diatoms of North America. Retrieved July 22, 2018, from


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