• Category
  • Length Range
    63-127 µm
  • Width Range
    11.7-13.6 µm
  • Striae in 10 µm



Valves are linear with weakly convex sides. Apices are subcapitate to broadly subrostrate. The ends and center of larger specimens are occasionally swollen. The axial area is about 1/3 the valve width and widens to an irregularly rhombic central area. The striae in the central area can vary widely across populations and might contain an absent marginal striae on one or both sides or a broad asymmetric transverse fascia. In the central area of some specimens, four indistinct markings might be visible in LM. The raphe is broadly lateral with ?-shaped terminal fissures. Striae are radiate in the center becoming convergent towards the ends.


This large taxon was recorded in sediments of lakes in Pennsylvania, New York, and New Jersey. 

The species was originally described from Scotland (Krammer 1992).

Original Description

  • Author
    Krammer 1992
  • Length Range
    55-130 µm
  • Width
    5.5-15 µm
  • Striae in 10µm

Original Images

Pinn subgibba org img 02
Pinn subgibba org img 01
Pin subgibba org descp

Cite This Page

Aycock, L. (2023). Pinnularia subgibba. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/pinnularia-subgibba


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