• Category
  • Length Range
    30-88 µm
  • Width Range
    6-7.5 µm
  • Striae in 10 µm



Valves are linear-lanceolate, with the central margins nearly parallel. Apices are rounded and subrostrate. The striae are distinctly punctate, with coarse areolae (24-27 in 10 µm). The fibulae are in line with the striae, and may be difficult to discern. A central, longitudinal fold is absent.

Under the SEM, N. angustata has a longitudinal marginal rib on the opposite site of the raphe. Small areolae are present on either side of the raphe. These two features are not typical of either Nitzschia or Tryblionella and, therefore, the systematic position of this taxon is uncertain.


Screen  Shot 2015 02 11 At 12 02 09  Pm
Credit: USGS BioData
Distribution of Nitzschia angustata in continental U.S. rivers in the National Water Quality Assessment program. Retrieved 11 February 2015.

Original Description

  • Basionym
    Tryblionella angustata
  • Author
    W.Sm. 1853
  • Length Range
    8-16 µm
  • Striae in 10µm

Original Images

T Angustata Original Plate
T Angustata Original Description

EMAP Assessment

EMAP Distribution

Nitzschia Angustata   Smith   Grunow 3
Map 3

Response Plots

Nitzschia Angustata   Smith   Grunow

Cite This Page

Bishop, I, and Spaulding, S. (2015). Nitzschia angustata. In Diatoms of North America. Retrieved August 18, 2018, from https://diatoms.org/species/nitzschia_angustata_1


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