• Category
  • Length Range
    180-370 µm
  • Width Range
    32-48 µm
  • Striae in 10 µm
  • Reported As
    Pinnularia latevittata var. domingensis (Patrick and Reimer 1966, pg. 631, pl. 62, fig. 1)
    Pinnularia nobilis (Krammer 1992, Fig 73:2)



The valves are large, linear, with an inflated middle part and subcapitate-cuneate apices. The length-to-width ratio is 5.5–7.7. The axial area is linear and about 1/4–1/3 of the valve width. Occasionally, there are irregular depressions on the external surface of the axial area, mostly along the external raphe fissure. The central area is round or elliptical, not always well separated from the axial area, usually wider on the primary valve side. The external raphe slit is only slightly curved so that the raphe appears lateral in LM. The central pores are small and round. The central nodule is prominent, with two depressions on its internal surface. The terminal raphe fissures are hook-shaped and extend onto the valve mantle. The striae (alveoli) are covered externally by silica plates perforated by pores arranged in 7–8 rows. The inner openings of the alveoli are approximately 1/2 the length of the stria in the narrowest part of the valve. Under LM their borders appear as two longitudinal lines: one transects the striae about 4–7 μm from their inner ends and is usually easily observed with LM, while another line runs 2–5 μm from the valve margin and is sometimes not detectable with LM. Striae continue to the valve mantle without any interruption at the valve face–mantle junction, where there are occasional spines on some virgae, which are widened at the spine base. The spines are not found at the valve apices, and their density is variable.


This taxon is found in lakes of Eastern United States with pH 4.3–7.7, conductivity 13–417 μS/cm, TP 6–80 μg/L and TN 238–1099 μg/L, with average values indicating a preference for slightly acid, soft waters of relatively low nutrient content and trophic status.

Original Description

  • Author
    Krammer 2000

Original Images

Pinnularia alabamae Orig Ill
Pinnularia alabamae Orig Descr

Cite This Page

Potapova, M. (2023). Pinnularia alabamae. In Diatoms of North America. Retrieved December 02, 2023, from https://diatoms.org/species/pinnularia-alabamae


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