• Category
  • Length Range
    7-21 µm
  • Width Range
    4-5 µm
  • Striae in 10 µm
  • Synonyms
    Navicula subbacillum 1937
  • Reported As
    Navicula stroemii (Krammer and Lange Bertalot 1986, Pl. 69, Figs 4-6)



Valves are linear to linear-elliptic in outline, with broadly rounded apices. The raphe is straight, with straight proximal ends. The terminal raphe fissures are gently deflected. The axial area is linear, with grooves sometimes visible under LM as parallel lines on each side of the raphe. A conopeum partially covering the grooves is present, but difficult to resolve in LM. The central area is small and circular, or may be nearly absent in some specimens. Striae are radiate, weakly curved toward the valve margin and sparse in the valve center. Polar bars are absent.

Navicula vasta is considered a heterotypic synonym by Falasco et al. (2009).


This taxon was documented in rivers and lakes of the northeast United States, but likely has a much broader distribution in North America.

Original Description

  • Basionym
    Navicula subbacillum
  • Author
    Hust. 1937
  • Width
    3.5-4.5 µm
  • Striae in 10µm

Original Images

Navicula subbacillum orig illus
Navicula subbacillum orig desc

Cite This Page

Bishop, I. (2021). Sellaphora subbacillum. In Diatoms of North America. Retrieved April 14, 2024, from https://diatoms.org/species/sellaphora_subbacillum


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