• Category
  • Length Range
    4.6-14.5 µm
  • Width Range
    2.6-3.5 µm
  • Striae in 10 µm
  • Synonyms
    Navicula minima var. atomoides (Grunow) Cleve
  • Reported As
    Navicula tantula (Hustedt 1934, pl. 399, figs 54-57)
    Eolimna minima (Moser et al. 1998, vol. 38, pg. 153)
    Eolimna tantula (Werum and Lange-Bertalot 2004, pg. 147, pl. 39, figs 8, 9; pl. 40, fig. 1)



Valves are small, linear to linear-elliptic with broadly rounded apices. The axial area is narrow, widening slightly toward the central area. The central area is distinctly rectangular or bow tie-shaped, with one areola of each stria extending onto the shallow mantle. The raphe is filiform, with proximal ends slightly 'tear-drop' shaped. Distal raphe ends are deflected to same side, terminating internally in small helictoglossae. Striae are radiate, uniseriate, and noticeably curved near the central area. Areolae are occluded internally. Polar bars are absent, but large apical perforations are present and occluded internally.

There has been much confusion regarding the taxonomic identity of Sellaphora atomoides and related species. The recent treatment of the former Eolimna minima and Sellaphora seminulum species complexes are further explained in Wetzel et al. (2015), and the specimens illustrated here appear to agree with the treatment of S. atomoides described by the Wetzel et al.


Sellaphora atomoides has been verified from aerial habitats and 'pristine' conditions. The taxonomic treatment and autecology of S. atomoides is very recent and has likely been reported under different names in the past, including Eolimna minima, Eolimna tantula, and Sellaphora seminulum. Because small-celled naviculoid taxa are often dominant in benthic freshwater communities, they are considered ecologically important taxa and in need of revision and further scrutiny. The recent treatment by Wetzel et al. (2015) will aid in clarifying the habitat preferences and distribution of S. atomoides and related taxa.

Original Description

  • Basionym
    Navicula atomoides
  • Author
    Grunow 1880
  • Length Range
    8 µm
  • Width
    4 µm
  • Striae in 10µm

Original Images

Satomoides Orig Drawings
Satomoides Orig Desc

Cite This Page

Minerovic, A. (2016). Sellaphora atomoides. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/sellaphora_atomoides


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