• Category
  • Length Range
    22.4-49.5 µm
  • Width Range
    3.5-4.5 µm
  • Striae in 10 µm
    > 35



Frustules are lightly silicified. In girdle view, valves are sigmoid and narrow. Girdle bands are absent. Valves are lanceolate to rhomboid with sharp apices. Striae are not resolvable with light microscopy. The fibulae are irregularly spaced and number 8-11 in 10 µm. Fibulae, however, are not widely spaced at the central part of the valve.


Original Description

German: Schalen typisch lanzettlich mit spitzen, nicht vorgezogenen Enden, 20-40 µm, lang, 3-4 µm breit. Kiel stark exzentrisch, Kielpunckte durchschnittlich etwa 10 in 10 µm, mehr oder weniger unregelmäßig gestellt, transapikal strichförmig. Struktur äußerst zart, bisher nicht aufgelöst. Abb.91-94.

Latin: Valvae lanceolatae apicibus acutis non protractis, 20-40 µm longae, 3-4 µm latae. Carina valde excentrica punctis carinalibus plus minusvae 10 in 10 µm, transapicaliter elongatis, irregulariter positis. Structura delicatissima, striae transapicales inconspicuae.

  • Author
    Hust. 1957
  • Length Range
    20-40 µm
  • Width
    3-4 µm

Original Images

Ni Sociab Drawing  Hustedt 1957
Ni Sociab Describe  Hustedt 1957 1

EMAP Assessment

EMAP Distribution

Nitzschia Sociabilis 40 Copy
Map 40

Response Plots

Nitzschia Socialbilis Copy

Citations & Links

Cite This Page

Manoylov, K. (2011). Nitzschia sociabilis. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/nitzschia_sociabilis


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