• Category
  • Length Range
    35-56 µm
  • Width Range
    5.7-6.2 µm
  • Striae in 10 µm



Valves are linear, with either straight or slightly convex margins. The apices are offset and subcapitate to rostrate. The raphe is lateral. The proximal raphe ends are closely placed and the terminal fissures are sickle-shaped. The axial area is narrow and widens to a central area with a broad, transverse fascia. Striae are radiate in the center, becoming convergent toward the ends. The length-to-width ratio is greater than 6 and as high as 9 in larger specimens.


This taxon has been verified in the NEON study site at Suggs Lake, Florida.

Original Description

  • Author
    Krammer 1992
  • Length Range
    30-58 µm
  • Width
    4.7-7.5 µm
  • Striae in 10µm

Original Images

Pinn subcapitata var elongata org img1
Pinn subcapitata var elongata org img2
Pinn subcapitata var elongata org descrp

Cite This Page

Aycock, L. (2022). Pinnularia subcapitata var. elongata. In Diatoms of North America. Retrieved May 29, 2024, from https://diatoms.org/species/pinnularia-subcapitata-var-elongata


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