• Category
  • Length Range
    48-53 µm
  • Width Range
    9-10 µm
  • Striae in 10 µm
    8-9 at the center, 11-12 towards the apices



Valves are lanceolate with elongate-protracted, rounded apices. The axial area is narrow, straight, widening to form an irregularly-rounded to elliptical central area. The central area is formed by shortened striae that are also more widely spaced than elsewhere on the valve. The raphe is lateral, slightly arched, with dilated proximal raphe ends. Striae are distinctly lineolate, radiate around the center, becoming parallel, then convergent at the ends.

Taxonomic note: We present N. rhynchocephala following Lange-Bertalot (2001). The specimen illustrated as N. rhynchocephala in Patrick & Reimer (1966) corresponds to our treatment of N. rhynchotella. The type material of N. rhynchocephala, however, has not been investigated and further work may clarify the original type as designated.


This taxon is typically low in abundance and tends to occur in sites with lower nutrient concentrations.

Original Description

  • Author
    Kütz. 1844

Original Images

N Rhynchocephala  Kutzing 1844

Citations & Links

Cite This Page

Kociolek, P. (2011). Navicula rhynchocephala. In Diatoms of North America. Retrieved June 19, 2024, from https://diatoms.org/species/navicula_rhynchocephala


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