• Category
  • Length Range
    153-255 µm
  • Width Range
    39-50 µm
  • Striae in 10 µm
    8-10 at the valve center, 13-16 at the apices
  • Reported As
    Cymbella heteropleura var. subrostrata (Patrick & Reimer 1975, p. 38, plate 6, fig. 1)



Valves are broadly lanceolate and slightly to moderately dorsiventral in large and small specimens, respectively. The arched dorsal and ventral margins taper to subtly protracted apices. The axial area is wide and expands gradually along the valve midline from the apices toward a somewhat wider and rounded central area. The raphe is lateral but becomes filiform near the proximal and distal ends. Proximal raphe ends with distinct ventrally deflected "crochet hooks" or "shepherd's crooks". Distal raphe fissures are bayonet-shaped and deflected dorsally. Striae are radiate throughout and distinctly punctate. Areolae are very coarse and number 11-15 in 10 µm.


Cymbopleura subrostrata is widely distributed in lakes, ponds, fens and headwater streams in the northern Rocky Mountains of western Montana. Here it prefers cold oligotrophic waters with circumneutral pH (range 6.02-7.90) and low specific conductance (range 22-168 µS/cm).

Kootenai  Pond And  Citadel  Peaks 1
Credit: Loren Bahls
Kootenai Pond, Glacier National Park, Montana: home of Cymbopleura subrostrata.

Original Description

  • Basionym
    Cymbella heteropleura var. subrostrata
  • Author
    Cleve 1894

Cite This Page

Bahls, L. (2012). Cymbopleura subrostrata. In Diatoms of North America. Retrieved July 13, 2024, from https://diatoms.org/species/cymbopleura_subrostrata


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