• Category
  • Length Range
    4.2-13 µm
  • Width Range
    2.8-4.2 µm
  • Striae in 10 µm
  • Reported As
    Eolimna minima (Moser et al. 1998, Bibliotheca Diatomologica, vol. 38, p. 153)



Cells small, elliptic to oval, with broadly rounded apices. Striae radiate and uniseriate throughout. Striae bordering central area slightly curved. Shorter striae present in middle of valve forming irregular and asymmetric "bow-tie" shaped to irregularly squared central area. Axial area linear, widening slightly toward the central area. Raphe straight with proximal raphe ends tear-drop shaped. Internally, distal raphe fissures end in small helictoglossae. Areolae vary in diameter and shape. Usually, areolae closest to raphe are larger and slightly angular, becoming smaller and more rounded towards margins. Areolae occluded internally.


Sellaphora nigri is considered to be widely distributed and pollution-tolerant.

Original Description

  • Basionym
    Navicula nigri
  • Author
    De Not. 1872
  • Length Range
    ~10 µm

Original Images

Sell Nig Orig Desc

Cite This Page

Minerovic, A. (2016). Sellaphora nigri. In Diatoms of North America. Retrieved April 16, 2024, from https://diatoms.org/species/sellaphora_nigri


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