• Category
  • Length Range
    54-72 µm
  • Width Range
    31-39 µm
  • Striae in 10 µm
  • Synonyms
    Cymatopleura internationale Bahls 2013
  • Genus Considered



Valves are elliptic with short apiculate apices. One to 3, but typically 2, undulations are evident across the valve face. Fibulae are regularly spaced and number 8-9 in 10 µm. The raphe is contained in a canal along the margin of the valve. Striae are irregular, often disorganized, and composed of areolae of variable size and shape. Areolae number 10-15 in 10 µm.


This taxon is known only from the type locality, the southern shoreline of Waterton Lake at Goat Haunt in Glacier National Park, Montana. On the date this sample was collected (22 July 2009), water temperature was 19.7 C, pH was 8.53, and specific conductance was 133 µS/cm.

The  International At  Goat  Haunt  Olson  Creek  Drainage
Credit: Loren Bahls
The Canadian tour boat International docked at Goat Haunt on the American end of Waterton Lake in the Waterton/Glacier International Peace Park. The type sample for Cymatopleura internationale was collected along the shoreline at left.

Original Description

Valves elliptic with short apiculate apices. Valve length 54–72 μm; valve width 31–39 μm. One to 3 (typically 2) undulations evident across the valve face. Marginal ribs regularly spaced, 8–9 in 10 μm. Striae very irregular, often disorganized, 8–18 in 10 μm. Areolae of variable size and shape, 10–15 in 10 μm.

  • Author
    Bahls 2013
  • Length Range
    54-72 µm
  • Width
    31-39 µm
  • Striae in 10µm

Original Images

Cymatopleura internationale orig illus
Cymatopleura internationale orig descr


Mar 18, 2024 - Transfer from Cymatopleura to Surirella

From October 4, 2012 to March 17, 2024, this taxon appeared as Cymatopleura internationale Bahls. The new combination, Surirella internationalis (Bahls) Spaulding was made in Edlund et al. (2024). The taxon page was updated to reflect the transfer. - S. Spaulding

Cite This Page

Bahls, L. (2012). Surirella internationalis. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/surirella_internationalis


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