• Category
  • Length Range
    23.1-30.4 µm
  • Width Range
    4.0-4.5 µm
  • Striae in 10 µm



Valves are clavate, with a rounded, rostrate to subcapitate headpole and narrowly rounded footpole. The axial area is wide and lanceolate. The raphe is lateral and mildly undulate. Striae are short and radiate at the footpole, short and weakly radiate between apices, and longer and parallel at the headpole. A single stigmoid is present.

Under SEM, exterior openings of areolae are C-shaped. Externally the stigmoid is small and circular, while internally the opening is slit-like. Helictoglossae are distinct at both valve ends and internal proximal raphe ends are unilaterally deflected and recurved.


Gomphonema sierranum has been observed in the western and southeast United States. Populations in the west are rare, principally found in remote oligotrophic streams in the Sierra Nevada mountain range (Stancheva et al., 2016; personal observation). Populations in the southeast have been found throughout the Piedmont plateau, Blue Ridge, and Ridge and Valley upland areas (USGS SESQA survey).

Original Description

  • Author
    Stancheva and Kociolek 2016
  • Length Range
    17-31 µm
  • Width
    4-5.2 µm
  • Striae in 10µm

Original Images

G Sierrianum Orig Desc Plate1
G Sierrianum Orig Desc Plate2
G Sierrianum Orig Desc Text


Apr 20, 2018 - Correction of species epithet

Prior to this date, this taxon was posted as Gomphonema sierrianum. The epithet "sierrianum" is automatically corrected to "sierranum” in accordance with the International Code of Algae, Fungi and Plants, Art. 60.12.

Cite This Page

Bishop, I. (2017). Gomphonema sierranum. In Diatoms of North America. Retrieved April 16, 2024, from https://diatoms.org/species/gomphonema_sierranum


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