• Category
  • Length Range
    22.9-33.0 µm
  • Width Range
    7.2-9.2 µm
  • Striae in 10 µm
    10-12 dorsal, 11-13 ventral near valve center



Valves are strongly dorsiventral with narrow rostrate to subrostrate apices. The dorsal margin is strongly arched and the ventral margin is weakly convex. The axial area is narrow and linear. The central area is very small. Two, rarely 1 or 3, stigmata are present at the proximal ends of the middle ventral striae. The raphe is lateral, becoming filiform near the indistinct terminal fissures. Proximal raphe ends are reverse-lateral and deflected to the ventral side. Striae are slightly radiate, becoming strongly radiate near the apices. Areolae number 26-30 in 10 µm.


Cymbella affiniformis has been recorded from two small spring creeks in the Flathead and Mission Valleys of western Montana. At the time it was described, this species was known only from the type locality, a pond in southern Germany (Krammer 2002).

Stinger Creek  Lake County  Mt  Dfwp
Credit: Montana Department of Fish, Wildlife and Parks
Stinger Creek, Lake County, Montana: Home of Cymbella affiniformis.

Original Description

  • Author
    Krammer 2002
  • Length Range
    23-34 µm
  • Width
    7.4-8.7 µm
  • Striae in 10µm
    10-12 at the valve center, 14-15 near the ends

Original Images

Cymbella affiniformis orig desc
Cymbella affiniformis orig desc 2
Cymbella affiniformis orig descr

Cite This Page

Bahls, L. (2016). Cymbella affiniformis. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/cymbella_affiniformis


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