• Category
  • Length Range
    59.6-82.3 µm
  • Width Range
    15.7-18.6 µm
  • Striae in 10 µm
    10-13 near the valve center, up to 18 near the ends
  • Reported As
    Cymbella laterostrata var. alaskana (Patrick and Freese 1961, p. 263, plate 4, fig. 2)



Valves are broadly elliptic-lanceolate, with wide subrostrate apices. The axial area is narrow and close to the valve midline. The central area is a transverse rhomboid, sometimes asymmetric, and about 1/2 the valve width. The raphe is lateral, becoming filiform near the proximal and distal ends. Proximal raphe ends are somewhat inflated and bent towards the ventral side. Distal raphe ends are comma-shaped and deflected dorsally. Striae are radiate throughout and indistinctly punctate. Areolae number 28-30 in 10 µm.


Krammer (2003) reports that this taxon prefers oligotrophic waters with low electrolyte content and lives as epiphytes on mosses. Its distribution is reported as from Alaska, Canada, Lapland, Spitsbergen and Siberia.

Sample 8 1
Credit: Beverly Boynton, Adventurers and Scientists for Conservation
Small Lake, Coppermine Mountains, Nunavut, Canada: home of Cymbopleura tynnii.

Original Description

  • Basionym
    Cymbella pseudocuspidata
  • Author
    Krammer 1978
  • Length Range
    75 µm
  • Width
    18 µm

Original Images

Cymbella tynnii orig illus
Cymbella pseudocuspidatai orig illus 2
Cymbella pseudocuspidata orig descr

Cite This Page

Bahls, L. (2015). Cymbopleura tynnii. In Diatoms of North America. Retrieved June 13, 2024, from https://diatoms.org/species/cymbopleura_tynnii


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