• Category
  • Length Range
    49.6-71.1 µm
  • Width Range
    12.1-17.9 µm
  • Striae in 10 µm
  • Synonyms
    Pinnularia lata var. rabenhorstii (Grunow) Cleve 1895



Valves are linear with moderately convex margins. Apices are bluntly rounded. The axial area is narrow. The central area is small to moderately large, rounded, and somewhat asymmetric. The raphe is lateral and straight. Proximal raphe ends are bent to one side and tipped with inflated pores. Distal raphe ends are hook- or sickle-shaped. The broad striae are weakly radiate at the valve center, becoming parallel at the apices.


Pinnularia rabenhorstii prefers cold oligotrophic waters in the mountains (Krammer 2000). This species is uncommon in collections from the Northwest United States. The seven specimens pictured on this web page were collected from seven different lakes and ponds, all but one of them within a few kilometers of the Canadian border. At these sites pH ranged from 7.34 to 8.81 and specific conductance ranged from 12 to 31 µS/cm.

Loudon Lake
Credit: Ryan Davis, Adventurers and Scientists for Conservation.
Loudon Lake, Okanogan County, Washington: home of Pinnularia rabenhorstii.
Boundary Trail Pond3A
Credit: Ryan Davis, Adventurers and Scientists for Conservation
Boundary Trail Pond #3, Okanogan County, Washington.

Original Description

  • Basionym
    Navicula rabenhorstii
  • Author
    Grunow 1860

Cite This Page

Bahls, L. (2014). Pinnularia rabenhorstii. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/pinnularia_rabenhorstii


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