• Category
  • Length Range
    34.5-48.0 µm
  • Width Range
    9.0-10.5 µm
  • Striae in 10 µm
    33-35 in the center
  • Synonyms
    Frustulia rhomboides var. crassinervia (Bréb.) R.Ross
    Navicula rhomboides var. crassinervia (Bréb.) Grunow



Valves are rhomboid with undulate margins. Apices are narrowly rounded and moderately protracted. Both the longitudinal ribs and the raphe are slightly curved. The ribs are slightly constricted at the central nodule. The longitudinal striae are wavy, but not prominent. Striae are fine and mostly parallel; in some valves the striae are wavy along the length of the valve. At the apices, the striae are difficult to discern, but appear to be present in some specimens. The longitudinal ribs and helictoglossae fuse to form a small porte-crayon.

Images of F. crassinervia (Lange-Bertalot 2001, pl. 127, figs 7-15) suggest that the species has striae that circumradiate the apices.

Original Description

  • Basionym
    Navicula crassinervia
  • Author
    Bréb. in W.Sm. 1853

Original Images

 Navicula crassinervia orig illus
Navicula crassinervia orig descr

Cite This Page

Kociolek, P., Graeff, C. (2011). Frustulia crassinervia. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/frustulia_crassinervia


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