• Category
  • Length Range
    100-207 µm
  • Width Range
    27-39 µm
  • Striae in 10 µm
    8-10 at the valve center, 14-16 at the apices
  • Reported As
    Cymbella acutiuscula (Hein 1990, p. 31, plate 8, fig. 1)



Valves are broadly elliptic-lanceolate and slightly to moderately dorsiventral in large and small specimens, respectively. The arched dorsal and ventral margins taper to broadly rostrate apices. The axial area is wide and expands gradually along the valve midline from the apices toward a somewhat wider, rounded central area. The axial and central area are sometimes ornamented with faint spots that are about the same size as areolae, but irregularly arranged. The raphe is distinctly lateral and becomes reverse-lateral near the proximal and distal ends. Proximal raphe ends with small ventrally deflected "crochet hooks" (Figs 5 and 6 above), but in most specimens the ends appear to be simply expanded. Distal raphe fissures are comma-shaped and deflected dorsally. Striae are radiate throughout and distinctly punctate. Areolae are coarse and number 16-18 in 10 µm.


Cymbopleura heinii has been recorded from 13 lakes, ponds and fens in the northern Rocky Mountains of western Montana. The population described here is from Johns Fen in Glacier National Park, where it is abundant. Here pH measured 6.02 and specific conductance measured 58 µS/cm. Hein (1990) reported this species (as Cymbella acutiuscula) from Adak Island, Alaska.

P9030262 1
Credit: E. William Schweiger, National Park Service
Red Eagle Pond, Glacier National Park, Montana: home of Cymbopleura heinii.

Original Description

Valves slightly dorsiventral, broadly elliptical-lanceolate, dorsal and ventral margins arched, tapering abruptly to moderately wide rostrate ends. Length 115-137 µm, breadth 30-32 µm, maximum length/breadth ratio 3.6. Axial area moderately wide, almost in the median line of the valve, broadening gradually towards valve centre to form a not distinctly set off elliptical central area, 1/3 the valve breadth, asymmetrical and more well developed dorsally. Raphe distinctly lateral, narrowing towards the distal ends, appearing strongly reverse-lateral near the proximal ends. Proximal raphe ends crochet-hooked and ventrally tipped, terminal fissures comma-shaped and dorsally deflected. Striae radiate throughout, distinctly punctate. Striae in the middle portion (dorsal) 8-9/10 µm, 12-13/10 µm towards the ends, puncta 15-17/10 µm.

  • Author
    Lange-Bert. and Krammer in Lange-Bert. and Genkal 1999
  • Length Range
    115-137 µm
  • Width
    30-32 µm
  • Striae in 10µm
    8-9 at the valve center, 12-13 near the ends

Original Images

Cymbopleura heinii orig desc
Cymbopleura heinii orig illus
Cymbopleura heinii orig descr

Cite This Page

Bahls, L. (2012). Cymbopleura heinii. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/cymbopleura_heinii


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