• Category
  • Length Range
    75-205 µm
  • Width Range
    8-11 µm
  • Striae in 10 µm
  • Synonyms
    Rhopalodia gibba (Ehrenb.) O.Müll.



Valves are usually seen in girdle view. Valves are linear, with apices bent toward the ventral margin. The central valve is inflated. Often, a visible "notch" is present on the dorsal margin. The raphe is positioned in a canal along the dorsal margin, and the proximal raphe ends and helictoglossae are not evident. Costae are prominent, and extend across the valve face. Between each costa are 2-3 rows of single, punctate striae. Costae number 5-8 in 10 µm.

Both Patrick and Reimer (1966) and Krammer and Lange-Bertalot (1988) give dimensions of up to 300 µm in length.


This species usually grows as an epiphyte, but it may also be found in the benthos. Because it may host endosymbiotic cyanobacteria, it may thrive in low nitrogen habitats.

Original Description

  • Basionym
    Navicula gibba
  • Author
    Ehrenb. 1832

Original Images

Navicula Gibba Or Descr


May 16, 2020 - Revision to previous name

From 2011 to May 2020, this species appeared as Rhopalodia gibba (Ehrenb.) Kütz., which had been its accepted name. Phylogenetic analysis of diatoms with a canal raphe system showed that the genus Rhopalodia is not a monophyletic group (Ruck et al. 2016). In order for the classification to reflect evolutionary relationships, the least disruptive way to achieve the monophyly of taxa in this lineage was to subsume Rhopalodia into Epithemia. - M. Potapova

Cite This Page

Kociolek, P. (2011). Epithemia gibba. In Diatoms of North America. Retrieved July 15, 2024, from https://diatoms.org/species/epithemia_gibba


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