• Category
  • Length Range
    32-39 µm
  • Width Range
    7.0-8.3 µm
  • Striae in 10 µm
  • Synonyms
    Navicula viridula var. germainii (J.H.Wallace) Lange-Bert.



Valves are lanceolate with drawn-out apices. The axial area is narrow and straight. The central area is slightly asymmetric and elliptical. The raphe is straight, with external proximal raphe ends slightly dilated and bent toward the primary side of the valve. The central nodule is asymmetrically expanded on the internal valve surface to the primary side. Terminal raphe fissures are hooked to the secondary valve side. Striae are radiate around the center, 13-15 in 10 µm, becoming parallel then convergent at the apices. The areolae are often visible under LM, ca. 30-32 in 10 μm.

Note that this concept of Navicula germainii follows that of Lange-Bertalot (2001), but differs from the original concept of Wallace (1960), who did not distinguish between N. germainii and N. rostellata sensu Lange-Bertalot. Patrick (Patrick and Reimer 1966) designated a lectotype specimen of Navicula germainii, but Patrick's circle on holotype slide of N. germainii contains several specimens of both N. germainii and N. rostellata sensu Lange-Bertalot. The illustration of the lectotype in Patrick and Reimer (1966, Fig. 48:8) does not correspond to any of these specimens.


This taxon widespread in rivers across the US and is considered to be tolerant to a range of conditions. In the EPA Western EMAP survey, it was commonly found in plains rivers and in sites with greater human impact. It typically occurred in waters with pH of greater than 7.5, high pH, conductivity, alkalinity, dissolved organic carbon, and sodium. It was tolerant of embedded streams and measures of total human disturbance.

Original Description

Valvis late lanceolatis 34-37 μ longis, 7-9.5 μ latis. Apicibus plus minus porrectis, subcapitatis, striis granulatis, centralibus radiantibus sed apices versus leviter convergentibus, 13-14 in 10 μ.

  • Author
    J.H.Wallace 1960
  • Length Range
    34-37 µm
  • Width
    7-9.5 µm
  • Striae in 10µm

Original Images

Na Germ  Or Ill
Nagermain  Or Descr

Cite This Page

Potapova, M. (2011). Navicula germainii. In Diatoms of North America. Retrieved June 21, 2024, from https://diatoms.org/species/navicula_germainii


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