• Category
  • Length Range
    21-54 µm
  • Width Range
    15-33 µm
  • Striae in 10 µm



The valves are variable in size and shape and are more or less heteropolar. The headpole is broadly rounded, but the footpole varies between broadly rounded in the smaller valves and cuneately rounded in the larger valves. The valve face slightly concentrically undulate and is partially twisted about the apical axis. The fibulae are marginal and have a density of 6-8 per 10μm. The costae extend from the marginal area to the apical axial line in a density of 16-26 per 10μm. The areolae on the valve face, only visible in the SEM, are round and in rows of 1-2 near the apical axis and of 3-4 near the marginal area. There are what appear to be in the LM large areolae around the circumference of the valve but these are actually indentations in the valve face at the end of the striae.


Original Description

Cells heteropolar, more or less torsioned about the transapical axis. Valves ovoid, with broadly rounded headpole and more narrowly rounded footpole, 17-54 µ long, 10-25 µ broad. wings little developed, "windows" not apparent. Wing canals 5-7 in 10 µ, extending to center of valve where they are interrupted by a narrow pseudoraphe. Surface of central portion of valve striate, striae about 18 in 10 µ.

  • Author
    R.L.Lowe 1973
  • Length Range
    17-54 µm
  • Width
    10-25 µm
  • Striae in 10µm

Original Images

New Sp Card002 1
New Sp Card001

Cite This Page

English, J, and Potapova, M. (2011). Surirella iowensis. In Diatoms of North America. Retrieved July 17, 2018, from https://diatoms.org/species/surirella_iowensis


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