• Category
  • Length Range
    29-50 µm
  • Width Range
    10.1-12.4 µm
  • Striae in 10 µm
    12-16 at the valve center, 16-19 near the apices



Valves are lanceolate and slightly dorsiventral, with almost equally arched dorsal and ventral margins. Apices are rostrate to subcapitate. The axial area is narrow and expands gradually towards a large rounded, somewhat rhomboid central area. The raphe is lateral and becomes filiform near the proximal ends, which are deflected slightly towards the ventral margin. Proximal raphe ends are weakly expanded and end with short hooks. The distal raphe is filiform and fissures are deflected dorsally, in the shape of a question mark. Striae are slightly radiate throughout and somewhat more closely spaced on the ventral side and near the apices. Areolae number about 35 in 10 µm.

This species is easily confused with Cymbopleura naviculiformis, which differs slightly in the shape of the valve and the degree of arch in the ventral margin.


In North America, this taxon is known from a small pond in Mount Rainier National Park, Washington. Krammer (2003) reports C. sublanceolata from the Alps and from nordic and subarctic oligotrophic waters with low to moderate electrolyte content.

Frog Pond Near  Dewey  Lake 1
Credit: Ryan Davis, Adventurers and Scientists for Conservation
Frog pond above Dewey Lake, Mount Rainier National Park, Washington: home of Cymbopleura sublanceolata

Original Description

Valves slightly dorsiventral, lanceolate, dorsal and ventral margins arched, tapering abruptly to rostrate or capitate ends. Length 30-64 µm, breadth 10-12 µm, post initial cells sometimes up to 13.2 µm, maximum length/breadth ratio 4.5. Axial area narrow, almost in the median line of the valve. Central area about 1/2 the valve breadth, rounded, distinctly set off, sometimes asymmetrical. Raphe lateral, narrowing towards the distal ends, appearing subtly reverse-lateral near the proximal ends. Proximal raphe ends barely expanded as central pores and somewhat ventrally tipped; terminal fissures ?-shaped and dorsally deflected. Striae radiate throughout, indistinctly punctate-lineate. Striae in the middle portion (dorsal) 12-14/10 µm, 15/10 µm towards the ends, puncta 30-33/10 µm.

  • Author
    Krammer 2003
  • Length Range
    30-64 µm
  • Width
    10.0-13.2 µm
  • Striae in 10µm
    12-14 in the valve center, 15 towards the ends

Original Images

Cymbopleura sublanceolata orig illus
Cymbopleura sublanceolata orig illus 2
Cymbopleura sublanceolata orig descr

Cite This Page

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


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