• Category
  • Length Range
    30-49 µm
  • Width Range
    11.3-15.0 µm
  • Striae in 10 µm
  • Synonyms
    Gomphonema truncatum var. turgidum (Ehrenb.) R.M.Patrick 1975



Valves are strongly asymmetric to the transapical axis, with a broad, truncated headpole, nearly as wide as the central inflation. The footpole is narrow and rounded, with a porefield bisected by the distal raphe. The axial area is wide and linear-lanceolate. The raphe is complex and lateral. The central area is small with central striae of variable length, and containing a single isolated stigma. Striae are parallel to weakly radiate, except at the footpole, where they become strongly radiate. Areolae are coarse and easily visible in LM, measuring 21-26 in 10 µm. Voigt discontinuities are often visible.


This taxon was described by Ehrenberg (1854) from fossil deposits in New York and Rhode Island (Smithfield). It has been documented in recent surveys and lake sediment records across the country.

Original Description

- turgidum, Kielselguhr von New-York, Nord-Amerika, T. II. II. F. 40.; Kieselguhr, Smithfield, Rhodes Island, Nord-Amerika, T. IV. II. F. 34.

  • Author
    Ehrenb. 1854

Original Images

Ehrenberg 1854 T2 fig40
Ehrenberg 1854 T4 fig34
Ehrenberg 1854  pg 15

Cite This Page

Bishop, I. (2015). Gomphonema turgidum. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/gomphonema_turgidum


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