• Category
  • Length Range
    41.8-55.5 µm
  • Width Range
    6.5-8.9 µm
  • Striae in 10 µm
    15-17 at the valve center, 20-24 at the ends on the dorsal side
  • Reported As
    Cymbella angustata var. linearis (Ross 1947, p. 216)



Valves are linear and barely slightly dorsiventral, with nearly flat, parallel sides. The ventral side may be weakly concave. Apices are subrostrate to cuneate. The axial area is narrow but and widens slightly near the central area. The central area is rounded, about half as wide as the valve, and formed by shallow depressions on the dorsal and ventral sides. The raphe is lateral, becoming filiform near the ends. Proximal raphe ends are unexpanded and deflected ventrally. Distal raphe ends are hooked towards the dorsal side. Striae are radiate throughout and more widely spaced around the central area. Areolae in the striae are difficult to resolve in LM and number 28-34 in 10 µm.


This taxon was originally described from material collected in Sweden. The specimens shown here were collected from an oxbow of the Swan River in northwest Montana and from Lower Pond No. 1 at the Mexican Cut Nature Preserve in Colorado. The pH of the pond at Mexican Cut measured 6.88 and specific conductance measured 28 µS/cm.

Mexican Cut Ponds  Nature Conservancy
Credit: Nature Conservancy
Mexican Cut Nature Preserve, Gunnison County, Colorado: home of Encyonema willeyorum

Original Description

  • Basionym
    Cymbella incerta var. linearis
  • Author
    Fontell 1917

Original Images

Cymbopleura incertiformis var. linearis orig illus

Cite This Page

Bahls, L. (2014). Cymbopleura incertiformis var. linearis. In Diatoms of North America. Retrieved June 13, 2024, from https://diatoms.org/species/cymbopleura_incertiformis_var._linearis


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