• Category
  • Length Range
    81-124 µm
  • Width Range
    16.3-23.5 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis aff. catharinae (Bahls 2010, p. 61, figs. 1-5)



Valves are lanceolate with rounded, unprotracted apices. A relatively deep pseudoseptum occupies each apex. The axial area is narrowly lanceolate and widens gradually to the central area. Central stauros is nearly rectangular, expanding somewhat toward the valve margins, and positioned diagonally at a low angle to the transapical axis. The raphe is distinctly lateral with straight proximal ends that are weakly inflated. Striae are radiate throughout. Areolae are relatively coarse and number 12-16 in 10 µm.


Stauroneis thompsonii is known so far only from the type locality, where it is uncommon. It was first collected by the author in September 1990. In September 2012, the author returned to the same location and collected another sample containing this species. On the latter date, water temperature measured 12.5 C, pH was 8.83, and specific conductance was 107 µS/cm.

Upper  Wolverine  Lake 2
Credit: Loren Bahls
Wolverine Lake (upper), Kootenai National Forest, Lincoln County, Montana: home of Epithemia smithii

Original Description

Valves lanceolate with rounded, unprotracted apices. A deep pseudoseptum occupies each apex (Fig. 24). Valve length 88–105 µm; valve width 16.3–17.5 µm. Raphe lateral with straight proximal ends, slightly inflated. Distal raphe ends hooked to same side. Axial area narrowly lanceolate, widens gradually towards central area. Central stauros nearly rectangular and placed somewhat diagonally to apical axis. Striae radiate throughout, 17–18 in 10µm. Areolae in striae 12-15 in 10 µm.

  • Author
    L.L.Bahls 2012
  • Length Range
    88-105 µm
  • Width
    16.3-17.5 µm
  • Striae in 10µm

Original Images

Staurosthompson Origimag
Staurosthompson Origdesc

Cite This Page

Bahls, L. (2012). Stauroneis thompsonii. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/stauroneis_thompsonii


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