• Category
  • Length Range
    30.8-49.6 µm
  • Width Range
    7.8-9.9 near head pole; 8.3-10.0 at the valve center µm
  • Striae in 10 µm



Valves are clavate and triundulate. The headpole is narrow and rostrate to subcapitate. The footpole is subrostrate. Valves are widest at the center valve. The undulation nearest the head pole is coequal with, or narrower than, the central undulation. The undulation near the foot pole is narrower than the undulation near the head pole, giving the valve a wedge-shaped appearance. The axial area is narrow. The central area is an incomplete rectangular fascia, interrupted on one side by a shorter stria with an isolated stigma, and on the other side by 0-2 shorter striae. The raphe is lateral, becoming filiform near the proximal and terminal ends. Proximal raphe ends are straight and terminate in slightly inflated ends. Terminal raphe fissures are deflected to the same side at approximately 45 degrees. Striae are curved and nearly parallel near the central area and become radiate and straight near the apices. Areolae in the striae are fine and are greater than 30 in 10 µm.


This taxon was described from material collected in Spitsbergen, Norway. The specimens shown on this web page were collected from a small pool on the tundra of Nunavut (Canada) above the Arctic Circle (photo below). The pH of this pool at the time of collection was 8.10.

Sample 5 1
Credit: Beverly Boynton, Adventurers and Scientists for Conservation
Small pool on the tundra of Nunavut, Canada: home of Gomphonema nathorstii

Original Description

Cite This Page

Bahls, L. (2016). Gomphonema nathorstii. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/gomphonema_nathorstii


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