• Category
  • Length Range
    62.3-114.4 µm
  • Width Range
    19.6-25.1 µm
  • Striae in 10 µm
    8-9 at the valve center, 12-13 near the apices on the dorsal side



Valves are weakly dorsiventral and lanceolate with narrow beaked apices. The dorsal margin is more strongly arched than ventral margin, which may be nearly flat in the smallest specimens. The axial area is moderately wide, about one-fourth to one-third the width of the valve. The central area is rounded and slightly wider than the axial area. The raphe is lateral and narrows near the weakly expanded proximal ends, which are tipped slightly towards the ventral side. Distal raphe ends are bayonet-shaped and more or less straight. Striae are radiate, but become parallel very near the apices. Areolae in the striae are easily resolved in LM and number 16-22 in 10 µm.


Cymbopleura perprocera was described from material collected from a Sphagnum moor pond in northwest Finland. Krammer (2003) reports this species has a sporadic distribution in lakes of Finnish Lapland, where the water is low in nutrients and electrolytes. The specimens illustrated here were collected from Hoskins Lake, a lowland lake surrounded by conifer forest in northwest Montana (photo below). Here pH measured 7.6 and specific conductance measured 67 µS/cm on the day that C. perprocera was collected.

Hoskins  Lake  Montana
Credit: thewesternnews.com
Hoskins Lake, Lincoln County, Montana: home of Cymbopleura perprocera.

Original Description

  • Author
    Krammer 2003
  • Length Range
    84-124 µm
  • Width
    23-26 µm
  • Striae in 10µm
    8-9 at the valve center, 15-16 near the apices on the dorsal side

Original Images

Cymbopleura perprocera orig desc
Cymbopleura perprocera orig desc
Cymbopleura perprocera orig descr2

Cite This Page

Bahls, L. (2014). Cymbopleura perprocera. In Diatoms of North America. Retrieved June 22, 2018, from https://diatoms.org/species/cymbopleura_perprocera


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