• Category
  • Length Range
    70.7-126.5 µm
  • Width Range
    46.4-80.7 µm
  • Striae in 10 µm
  • Synonyms
    Navicula striatula (Turpin) Ehrenb. 1832



Valves are elliptic to ovate, ranging from isopolar to heteropolar due to torsion along the apical axis. Apices broadly rounded. The axial area is ridge-like and appears to branch out between the valve porcae or ribs, extending to the valve margin. Length to width ratio of approximately 1.5. The valve face has large undulating porcae (ribs) that extend from the valve margin to the hyaline axial area. The ribs are not evenly spaced and are asymmetric in shape and size. Striae are located on the porcae; the area between porcae are covered in unorganized punctae. At the apex, hyaline undulations radiate from the central midline and create a triangular shaped area that is filled with striae. The raphe system is raised on a peripheral alar wing along the entire valve margin.


Surirella striatula is typically a marine species, but was found in the epiphyton and plankton of Salt Lake, Lac qui Parle County, Minnesota, USA.

It has been observed living in river algal mats in Uvs aimag (province), Davst sum (district), Jireg Gol, Mongolia (Edlund et al. 2001). This area is saline due to large salt rock deposits. This taxon has been found in lakes in British Columbia (Cumming et al. 1995), as well as in saline inland waters in Europe (Hustedt 1930).

Img 5572  Salt  Lake  Minnesota Resized
Credit: Mark Edlund
Salt Lake shoreline, Minnesota, USA

Original Description

  • Author
    Turpin 1828
  • Length Range
    100 µm
  • Striae in 10µm

Original Images

S Striatula Orig Illustration Gray
S Striatula Orig Description Gray

EMAP Assessment

EMAP Distribution

Surirella Striatula  Turpin 40
Map 40

Response Plots

Surirella Striatula  Turpin

Cite This Page

Fedrigon, P. (2016). Surirella striatula. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/surirella_striatula


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