• Category
  • Length Range
    75-205 µm
  • Width Range
    8-11 µm
  • Striae in 10 µm



Valves usually seen in girdle view. Valves are linear, with apices bent towards the ventral margin. The central valve is inflated, often with a visible "notch" 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 between 2 and 3 rows of singly punctate striae. Costae number 5-8 in 10 µm.

This species is usually an epiphyte, but may also be found in the benthos. Both Patrick & Reimer (1966) and Krammer and Lange-Bertalot (1988) give dimensions of up to 300 µm in length.


Original Description

  • Basionym
    Navicula gibba
  • Author
    Ehrenb. 1830

EMAP Assessment

EMAP Distribution

Rhopalodia Gibba   Ehrenberg   Mùller 3
Map 3

Response Plots

Rhopalodia Gibba   Ehrenberg

Cite This Page

Kociolek, P. (2011). Rhopalodia gibba. In Diatoms of North America. Retrieved February 24, 2020, from https://diatoms.org/species/rhopalodia_gibba


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