• Category
  • Length Range
    215.9-265.8 µm
  • Width Range
    38.9-47.8 µm
  • Striae in 10 µm



Valves are linear, with a strongly gibbous center and broadly rounded apices. The axial area is linear. The central area is elliptic and slightly wider on the primary valve side. Striae are radiate at the valve center and convergent and slightly bent at the apices. A boundary of the internal alveolae openings is visible in LM as a longitudinal line that is positioned close to axial area. The raphe is lateral with drop-shaped proximal raphe ends, deflected to primary side. The terminal raphe fissures are hook-shaped.


This diatom is quite large and rare compared to smaller taxa. It has been verified from lake sediments of northeastern lakes, particularly in Hammonton Pond, New Jersey.

Original Description

Valve strongly gibbous in the middle and gradually widened to the rounded ends; axial area broad, less than one-third the width of the valve, widened unilaterally in the middle; striae, 7 in 10 µ, crossed by a band nearly as wide as the length of the costae and scarcely distinct. L. 273 µ.

The central nodule is scarcely evident, probably because it is not so thick as in other forms. The outline is near to that of N. mesogongyla and certain forms of N. nobilis, differing from the later in the median line, striae and band width which is wider than that of P. latevittata var. domingensis Cl.

Hammonton Pond, N.J.
Pl 28, Fig, 2

A very beautiful form which I cannot find described or figured. It does not appear to be N. major var. turgidula Cl., which has a narrow band. In the fossil deposit from Hopkinton, N.H., valves occur similar in outline but smaller.

  • Author
    Boyer 1916
  • Length Range
    273 µm
  • Striae in 10µm

Original Images

Pinnularia pulchella orig illus 1
Pinnularia pulchella orig desc

Cite This Page

Kersey, M., Potapova, M. (2022). Pinnularia pulchella. In Diatoms of North America. Retrieved March 21, 2023, from https://diatoms.org/species/pinnularia-pulchella


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