• Category
  • Length Range
    170-275 µm
  • Width Range
    35-47 µm
  • Striae in 10 µm
  • Synonyms
    Pinnularia dactylus f. dariana (A.W.F.Schmidt) Cleve



Valves are linear-lanceolate, barely triundulate, or slightly expanded at mid-valve. Apices are broad and rounded. The axial area is linear-lanceolate, 1/4-1/3 of the valve width and gradually widens into a poorly separated central area. The central area is wider in the primary valve side.

Striae are radiate in the valve center and slightly convergent at the apices. One longitudinal line crosses the striae approximately in the middle (between the central area and valve margin). This longitudinal line is formed by the edge of internal alveolae openings is usually clearly visible under LM. A second longitudinal line is very close to valve margin and is only occasionally distinguishable in LM. The raphe is lateral, with slightly expanded central ends and sickle-shaped terminal fissures.

Note the valve outline is variable; some valves, such as those illustrated by Schmidt (1876), have rather smooth margins, lacking undulations. The specimen of P. dariana illustrated in Patrick and Reimer (1966) is depicted with a smooth outline, as is the original illustration in Schmidt (1876). The majority of populations, however, are characterized by slightly triundulate valves.


Pinnularia dariana is usually found in lakes, although some historic records of the taxon are from rivers (Hudson River and Neuse River).

Original Description

  • Basionym
    Navicula dariana
  • Author
    A.W.F.Schmidt 1876

Original Images

Pdariana Orig Ill
Pdariana Orig Descr

Cite This Page

Kersey, M., Potapova, M. (2022). Pinnularia dariana. In Diatoms of North America. Retrieved December 08, 2023, from https://diatoms.org/species/pinnularia-dariana


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