• Category
  • Length Range
    18.4-32.8 µm
  • Width Range
    2.2-2.9 µm
  • Striae in 10 µm
  • Reported As
    Nitzschia frustulum var. perminuta (Grunow in Van Heurck 1881)



Valves are linear, with largely parallel margins. In some specimens, the valve margins may be be slightly concave. Apices are rostrate to subcapitate. The raphe is positioned on an eccentric keel. Fibulae number 11-14 in 10 µm. On most valves. the two median fibulae are more widely spaced, creating a the appearance of a "central nodule". Striae are parallel and composed of indistinct areolae.


This species prefers circumneutral to slightly acidic waters with low conductivity and low nutrient levels. The specimens pictured on this web page are from a stream and a fen in northwestern Montana. At the time of sampling, the stream (Fish Creek, Flathead County) had a pH of 6.83, conductivity of 17 µS/cm, and total phosphorus concentration of 0.02 mg/L. The fen (Johns Fen, Glacier National Park) had a pH of 6.02 and a conductivity of 58 µS/cm. Krammer and Lange-Bertalot (1988) report this species as widespread in oligosaprobic, electrolyte-poor waters.

Original Description

Valves linear (small forms elliptic-lanceolate) with cuneate ends and rounded or protracted to capitate apices, 8-40 µm long, 2-3 µm wide. Transapical striae 27-32 in 10 µm. Keel very eccentric, fibulae 11-14 in 10 µm, the two median ones farther apart.

  • Author
    Lange-Bert. 1977
  • Length Range
    8-40 µm
  • Width
    2-3 µm
  • Striae in 10µm

Original Images

Nitzschia Acidoclinata Origimag001
Nitzschia Acidoclinata Origdesc001

Cite This Page

Bahls, L. (2016). Nitzschia acidoclinata. In Diatoms of North America. Retrieved April 14, 2024, from https://diatoms.org/species/nitzschia_acidoclinata


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