• Category
  • Length Range
    14-40 µm
  • Width Range
    5-8 µm
  • Striae in 10 µm
    10-13 in the center of the valve, 12-14 at the ends
  • Synonyms
    Gomphonema olivaceum (Hornem.) Bréb. 1838



Valves are clavate with a broadly rounded headpole and a narrow footpole. The valve tapers more strongly towards the footpole than to the headpole. The raphe is filiform and lateral. The raphe terminates internally distantly from the apices. The axial area is narrow, straight, and expanded laterally to form a rectangular central area bordered by shortened striae at or near the margin. Stigma are absent. Striae are costate and individual areoale are not visible in the LM. Striae are radiate. The apical pore fields appear (with DIC optics) more like condensed striae rather than differentiated apical pore fields.

Although this species was validly transferred to Gomphoneis (Ross and Sims 1978) (also see Dawson 1974), this classification has not been uniformly recognized and continues to appear as Gomphonema olivaceum.

Comments: In the USA flora we recognize a more narrow concept than that suggested by Krammer and Lange-Bertalot (1986, pl. 165). The specimens illustrated in figs. 4-6 are similar to those in North America. Figures 1-3 appear to be of another taxon.


Original Description

  • Basionym
    Ulva olivacea
  • Author
    Hornem. 1806

EMAP Assessment

EMAP Distribution

Gomphonema Olivaceum 20 Copy
Map 20

Response Plots

Gomphonema Olivaceum Copy 1

Cite This Page

Kociolek, P. (2011). Gomphoneis olivaceum. In Diatoms of North America. Retrieved June 25, 2018, from https://diatoms.org/species/gomphoneis_olivaceum


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