• Category
  • Length Range
    25-33 µm
  • Width Range
    5.8-7.2 µm
  • Striae in 10 µm



Valves are lanceolate with narrow, subrostrate ends. The raphe is filiform, ending in weakly expanded proximal pores that are relatively distant from one another. The axial area is narrow, widening slightly towards the central area. The central area is small and variable in shape with irregular margins. Striae are strongly radiate near the valve center, becoming parallel at the prominent Voigt discontinuities, and finally weakly convergent at the ends. Areolae in the striae are fine and difficult to resolve in LM, numbering about 30 in 10 microns.


There are 38 records of Navicula cryptofallax in the Montana Diatom Collection, most of them from flowing waters in the Northern Rocky Mountains, but also from standing waters. Here it prefers weakly alkaline water (mean pH = 7.9) of moderate conductivity (mean SC = 523 ┬ÁS/cm). Common diatom associates of Navicula cryptofallax are Amphora tumida, Diploneis parma, Encyonopsis perborealis, Encyonema elginense, Cymbopleura subaequalis, Caloneis schumanniana, and Cymbopleura subcuspidata..

Credit: Loren Bahls
The Gallatin River near Bozeman, Montana: home of Navicula cryptofallax.
Navcryptofallax Chem
Credit: Montana Diatom Database
Abundance-weighted means of selected water quality variables measured concurrently with the collection of samples containing Navicula cryptofallax.

Original Description

Valve stricte lanceolatae apicibus subcapitato-rostratiforme protractis, 23-30 microns longae, 5.5-6 microns latae, i.e. paulo variabiles quoad latitudinem. Raphe filiformis poris centralibus satis distantibus positis inter se; pori indecori visu, exigui, angusti etiam in REM numquam hamati nec declinati. Area axialis angusta parum dilatata ad mediam valvae versus. Area centralis modice parva plusminusve rotundata apparens. Striae transapicales valde radiantes, parallelae sub apices, 12-14 in 10 microns. Lineolae circiter 30 in 10 microns sed difficulter separandae (in LM). REM: Sternum parum elevatum super planitie externa valvae.

  • Author
    Lange-Bert. and G.Hofm in Lange-Bert. 1993
  • Length Range
    23-30 µm
  • Width
    5.5-6.0 µm
  • Striae in 10µm

Original Images

Ncryptofallax Origimag
Ncryptofallax Origdesc

Cite This Page

Bahls, L. (2011). Navicula cryptofallax. In Diatoms of North America. Retrieved June 13, 2024, from https://diatoms.org/species/navicula_cryptofallax


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