• Category
  • Length Range
    121.3-232.3 µm
  • Width Range
    21.8-29.9 µm
  • Striae in 10 µm
    10-12 at the valve center, up to 14 near the apices



Valves are long and slender, dorsiventral and lanceolate with rounded apices. Length-to-width ratio ranges from 4.9 in smaller specimens to 7.8 in the largest specimens. The dorsal margin is moderately arched. The ventral margin is slightly concave with a gibbous center. The axial area is narrow and linear, slightly wider than the raphe. The central area is small and ovoid. The raphe is lateral, becoming filiform near the proximal and distal ends. Externally, the proximal raphe ends are strongly recurved toward the ventral side. Terminal raphe fissures are deflected dorsally at an angle of almost 90 degrees. Striae are radiate throughout, becoming more strongly radiate near the apices. Areolae number 10-14 in 10 µm. Some elongate, stigma-like areolae appear at the proximal ends of the median ventral striae, but otherwise stigmata are absent.

Note on the type: The original description of Frustulia lanceolata (Agardh 1827) did not include illustrations. Krammer (2002, p. 125) examined the type material from Carlsbad (Bohemia) and did not find any cymbelloid diatoms. Krammer designated a neotype from Westphalia, Germany. Images of the neotype specimens (Krammer 2002, plate 144, figs 1-5) are given below.


Cymbella lanceolata is widespread in the Northern Rocky Mountains and Northwestern Great Plains, in lakes and streams where pH ranges from 7.50 to 8.54 and specific conductance ranges from 92 to 1227 µS/cm. This taxon is reported as an alkaliphil, widespread in the United States, and most common in littoral habitats associated with submerged aquatic plants and sometimes with partially decaying vegetation (Patrick and Reimer 1975).

Poplar  River
Credit: Loren Bahls
Poplar River on the Northwestern Great Plains in Montana: home of Cymbella lanceolata

Original Description

  • Basionym
    Frustulia lanceolata
  • Author
    C.Agardh 1827

Original Images

Frustulia lanceolata orig desc
Frustulia lanceolata orig illus
Frustulia Lanceolata  Agardh1827002

Cite This Page

Bahls, L. (2016). Cymbella lanceolata. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/cymbella_lanceolata


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