• Category
  • Length Range
    48-90 µm
  • Width Range
    12-15 µm
  • Striae in 10 µm
  • Synonyms
    Pinnularia acrospheria var. turgidula Grunow ex Cleve



Valves are linear, with a strongly gibbous center and broadly rounded, capitate apices. The axial area is linear, gradually widening into a lanceolate central area. The surface of the valve of both axial and central areas is mottled. The raphe is lateral with proximal raphe ends weakly expanded, deflected to primary side, and closely spaced. The terminal raphe fissures are sickle-shaped. Striae are weakly radiate at the valve center and parallel throughout the rest of the valve.


Pinnularia turgidula occurs in the benthos of lakes in the Northeastern US.

Original Description

  • Author
    Grunow ex Cleve 1895
  • Length Range
    48-70 µm
  • Width
    12 µm
  • Striae in 10µm

Original Images

Pinn turgidula Orig Descr

Cite This Page

Friedman, N., Potapova, M. (2021). Pinnularia turgidula. In Diatoms of North America. Retrieved May 25, 2024, from https://diatoms.org/species/pinnularia-turgidula


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