• Category
  • Length Range
    168.6-224.5 µm
  • Width Range
    16-19 µm
  • Striae in 10 µm
  • Synonyms
    Navicula transversa A. Schmidt
    Pinnularia major var. transversa A. Schmidt



Valves are linear, with a slightly gibbous center. The length to width ratio is relatively high (10-12 length to 1 width). The axial area is linear. Central area is asymmetric, wider on primary side of the valve and only slightly wider than the axial area. The striae are radiate at the center and convergent at the apices, where they are slightly longer on the primary valve side. The raphe is lateral ,with proximal ends slightly expanded and deflected. Terminal raphe fissures are hook-shaped.


Pinnularia transversa is found in lakes of northeastern US and in cold, low-nutrient waters in the Cascades and Rocky Mountains.

Original Description

5. 6. Monticello, N. transversa A. S. (It is so named because of the strikingly sloping and therefore wide-appearing fissure channels).

7. Cherryfield, 8. 9. Duck Pond, Waterford, Maine, after Grunow N. macilenta (Pinn.) E? it seems to me that the illustrations of N. macilenta fit the forms corresponding to T. 42, F. 9. 10.

  • Basionym
    Navicula transversa
  • Author
    A. Schmidt 1876
  • Length Range
    160-246 µm
  • Width
    17-23 µm
  • Striae in 10µm

Original Images

Pinnularia transversa orig illus 1
Pinnularia transversa orig illus2 1
Pinnularia transversa orig desc 1

Cite This Page

Kersey, M., Potapova, M. (2022). Pinnularia transversa. In Diatoms of North America. Retrieved June 19, 2024, from https://diatoms.org/species/pinnularia-transversa


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