• Category
  • Length Range
    33-42 µm
  • Width Range
    6.5-8.3 µm
  • Striae in 10 µm
    16-18 at the valve center, 18-20 at the valve ends
  • Synonyms
    Cymbella angustata (W.Sm.) Cleve 1894
  • Reported As
    Cymbella angustata (Hustedt 1930, p. 351, fig. 639)
    Cymbella angustata (Patrick & Reimer 1975, p. 22, plate 3, figs. 3-5)



Valves are lanceolate, subtly triundulate, and very slightly dorsiventral. Apices are rostrate in small specimens and subcapitate in larger specimens. The axial area is narrow and slightly arched with the concave margin towards the ventral margin. The central area is small and asymmetric with irregular borders. The raphe is lateral and follows the arch of the axial area. Proximal raphe ends are close and filiform, displaced slightly to the ventral margin. Distal raphe fissures are comma-shaped and deflected dorsally. Striae are parallel at the valve center, becoming radiate and then strongly radiate towards the apices. Areolae in the striae are not easily distinguished in LM and number 30-35 in 10 µm.


Cymbopleura angustata is found infrequently in oligotrophic headwaters of the northern Rocky Mountains. These waters are circumneutral to alkaline (pH range: 6.98 to 9.10) with low to moderate levels of dissolved solids (specific conductance range: 71-460 µS/cm). Patrick and Reimer (1975) report this species from cool to cold water habitats in New England states, east central states, Iowa, Michigan, and Montana. Krammer (2003) reports it as widely distributed in oligotrophic waters with low to moderate electrolyte content in nordic, subarctic, and temperate regions, including the Alps.

008 17 A
Credit: Loren Bahls
Redrock Lake, Glacier National Park, Montana: home of Cymbopleura angustata.

Original Description

  • Basionym
    Navicula angustata
  • Author
    W.Sm. 1853

Original Images

Navicula Angustata  Ill
Navicula Angustata  Descr

Cite This Page

Bahls, L. (2012). Cymbopleura angustata. In Diatoms of North America. Retrieved July 19, 2024, from https://diatoms.org/species/cymbopleura_angustata1


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