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.
Bishop, I., Spaulding, S. (2015). Nitzschia angustata. In Diatoms of North America. Retrieved November 21, 2024, 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.