• 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
    Gomphoneis olivacea (Hornem.) P.Dawson ex R.Ross and P.A.Sims 1978



Valves are clavate, with a broadly rounded headpole and a narrow footpole. The valve tapers more strongly toward 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 biseriate and radiate. The apical pore fields appear (with DIC optics) more like condensed striae rather than differentiated apical pore fields.

In North America, it has been treated as a member of Gomphoneis, as Gomphoneis olivacea (Hornem.) P.Dawson ex R.Ross and P.A.Sims 1978. This website also treated it as Gomphoneis olivacea, until 2019. In Europe, it has been treated within Gomphonema, as Gomphonema olivaceum (Hornem.) Bréb. 1838 (Hofmann et al. 2013, Levkov et al. 2016).

The phylogenetic relationships of Gomphonella olivacea, Gomphoneis and Gomphonema species have been examined based on gene sequences (18sV4, rbcl) (Jahn et al. 2019). This work led to the recognition and resurrection of Gomphonella (Hornem.) Rabenh., as well as the transfer of a number of species to Gomphonella. Future work will likely lead to further clarification of relationships in this group of diatoms.

Note that in the North American 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.


This species is common in North American streams and rivers. It is considered to be cosmopolitan, found across the world along with many varieties (Hofmann et al. 2013). A conspicuous feature of this diatom is its habit of extracellar polysaccaride production (EPS). It forms large gobs of mucilage from the apical porefield, and likely, from the raphe as well. Indeed, it was originally described by Hornemann (1810) for its production of mucilage, “Substantia gelatinosa lubrica supellucida".

Original Description

  • Basionym
    Ulva olivacea
  • Author
    Hornem. 1810

Original Images

Ulva Olivacea Orig Illus
Gomphonella Olivacea Lectotype

Citations & Links



  • Index Nominum Algarum
  • North American Diatom Ecological Database
    NADED ID: 37065


Jul 15, 2019 - Recognition of Gomphonella

From February 2011 until July 2019, this taxon appeared on this website as Gomphoneis olivaceum (Hornem.) P.A.Dawson ex R.Ross and P.A.Sims 1978. Following the publication of Jahn et al. (2019), the page was revised to show this taxon as Gomphonella olivacea (Hornem.) Rabenh.

The archived version of the page is available upon request. - S. Spaulding

Cite This Page

Kociolek, P., Spaulding, S. (2019). Gomphonella olivacea. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/gomphonella_olivacea


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