• Category
  • Length Range
    44-82 µm
  • Width Range
    13.2-16.4 µm
  • Striae in 10 µm
    8-11 at the valve center, 13-15 near the apices
  • Reported As
    Cymbella rainierensis (Patrick and Reimer 1975, pg 31, pl. 4, fig. 8)
    Cymbopleura subaustriaca (Zimmermann et al. 2010, pg 50, pl. 63, figs 8-11)
    Cymbopleura americana ((Schmidt) Krammer 2003, pl. 59, figs 1-3)



Valves are lanceolate and slightly dorsiventral with weakly protracted rostrate or apiculate apices. The axial area is narrow and positioned near the central apical axis. The central area is approximately half the width of the valve and rounded rhomboid in shape. The raphe is straight and lateral, becoming filiform at the proximal and distal ends. Proximal raphe ends are displaced ventrally, with slightly expanded ends that are indistinctly hooked toward the ventral side. Distal raphe ends are comma shaped and dorsally deflected. Striae are radiate throughout and indistinctly punctate. In most populations, areola density is 28-34 in 10 µm, although one population had an areola density of 20- 24 in 10 µm.

This taxon may be conspecific with Cymbella americana Schmidt. Apparently, there is no type material for C. americana. The illustrations from Schmidt's Atlas are reproduced in Krammer (2003, figs 59:1, 2). Krammer also presented an image of a taxon identified as C. americana from Tierra del Fuego (Krammer 2003, fig. 59:3).


This taxon has been recorded from several lakes, ponds and fens in Glacier National Park, Montana. In these waters it prefers circumneutral pH with low specific conductance. The type locality is Mowich Lake in Mount Rainier National Park, where pH measured 5.8 to 7.2. Sovereign (1963) reports that it is also found in over a dozen high mountain lakes in the Mount Rainier area. In the Montana Diatom Collection, we have two records from Mount Rainier National Park: Dewey Lake and a small pond near Dewey Lake. Zimmermann et al. (2010) reported this species (as Cymbopleura subaustriaca) from the Canadian High Arctic. Foged (1981) reported it from Alaska.

Frog Pond Near  Dewey  Lake
Credit: Ryan Davis, Adventurers and Scientists for Conservation
Frog pond near Dewey Lake, Mount Rainier National Park, Washington.

Original Description

Valves naviculoid, almost symmetrical in outline, lanceolate with rounded ends, 42-79 µm long by 13-16 µm wide. Raphe straight, almost on the median line. Axial area narrow lanceolate, central area rhomboidal. Striae lightly radial, at the middle 9 to 11 in 10 µm, closer at the ends, finely lineolate.

  • Basionym
    Cymbella rainierensis
  • Author
    Sovereign 1963
  • Length Range
    42-79 µm
  • Width
    13-16 µm
  • Striae in 10µm
    9-11 in the middle, closer at the ends

Original Images

Cymbella rainierensis orig illus
Cymbella rainierensis HOLOTYPE
 Cymbella rainierensis orig descr


Apr 21, 2024 - Species transfer

Cymbella rainierensis was transferred to Cymbopleura rainierensis by Bahls (2013). The page now reflects that transfer. - S. Spaulding

Cite This Page

Bahls, L. (2012). Cymbopleura rainierensis. In Diatoms of North America. Retrieved April 21, 2024, from https://diatoms.org/species/cymbella_rainierensis


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