• Category
  • Length Range
    29-41 µm
  • Width Range
    8.6-10.1 µm
  • Striae in 10 µm



Valves are lanceolate with obtusely rounded apices. Axial area is narrow and completely filled by the lateral raphe. Central area is small and irregular, typically bordered by alternately short-long-short striae on one or both sides. The distinctly lateral raphe becomes reverse lateral near the proximal ends, which are bent to the secondary side and distinctly inflated. Striae are radiate, becoming parallel to weakly convergent near the apices. Areolae are coarse and number 24-26 in 10 µm.


These images are from a population living in Sheridan Lake in the Black Hills National Forest, western South Dakota. Here, on the sample date, pH measured 9.73 and specific conductance measured 327 µS/cm. Lange-Bertalot (2001) reports this taxon from eutrophic to mesotrophic, calcium-rich standing waters in Europe. This taxon has been recorded infrequently in the United States.

Original Description

Schalen lanzettlich mit kaum merklich vorgezogenen, ziemlich spitz gerundeten Enden, um 44 µ lang, etwa 10 µ breit. Raphe gerade, mit etwas seitlich abgebogenen Zentralporen, Axialarea schmal linear, um den Zentralknoten plötzlich zu einer kleinen, querelliptischen Zentralarea erweitert. Transapikalstreifen im mittleren Teil radial und mit vereinzelten eingeschobenen kürzeren Streifen, an den Enden senkrecht zur Mittellinie, 12 in 10 µ, grob liniert, Längslinien etwa 25 in 10 µ, dem Schalenrand annähernd parallel, um den Zentralknoten nach aussen konvexe Bogen bildend.

  • Author
    Hust. 1945
  • Length Range
    44 µm
  • Width
    10 µm
  • Striae in 10µm

Original Images

Navoppug Typeimages
Nav Opp Origdes

Cite This Page

Bahls, L. (2012). Navicula oppugnata. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/navicula_oppugnata


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