• Category
  • Length Range
    62-90 µm
  • Width Range
    13.9-17.5 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis spec. 1 (Van de Vijver et al. 2004)



Valves are elliptic-lanceolate to linear-lanceolate with subcapitate apices. The axial area is linear, about three times wider than the raphe, and expands slightly near the central area. The central area is very wide at the valve margins and shaped like a bow tie. One to several short striae occur at each margin of the central area. Raphe branches are lateral but become filiform towards the distal and proximal ends. Distal raphe ends are hooked in the same direction. Proximal raphe ends are nearly straight and tipped with unexpanded central pores. Striae are somewhat wavy and strongly radiate throughout. Areolae are easily distinguished in LM and number 18-20 in 10 µm.


In the Northern Rockies, Stauroneis pax has been recorded from two lakes, a river, and a spring seep. All but one of these sites lies within the Waterton/Glacier International Peace Park. The remaining site, Lake Lavale, is in the Bob Marshall Wilderness about 100 km south of Glacier National Park. The pH of these waters ranges from 8.0 to 8.2 and specific conductance ranges from 149 to 183 µS/cm. Van de Vijver et al. (2004) reported this taxon from the Russian Arctic, where it was found in “a small, very shallow ditch, completely colonized by green algae”.

Lake  Levale 1
Credit: Loren Bahls
Lake Levale, Bob Marshall Wilderness, Lewis & Clark County, Montana: home of Stauroneis pax.

Original Description

Valves elliptic-lanceolate to linear-lanceolate with protracted subcapitate ends. Length 62-90 µm, width 13.9-17.5 µm. Axial area narrow, linear, widening close to the central area. Central area shaped like a bow tie, much wider at valve margins. One to several shortened striae on each margin. Raphe lateral, becoming filiform toward the endings of each branch. Distal ends hooked in the same direction, proximal endings nearly straight and tipped with unexpanded central pores. Striae somewhat wavy and strongly radiate throughout, 18-20 in 10 µm. Striae puncta easily distinguished in LM, 18-20 in 10 µm. For measurements, n = 9 valves.

  • Author
    Bahls 2010
  • Length Range
    62-90 µm
  • Width
    13.9-17.5 µm
  • Striae in 10µm

Original Images

Spax Origimag
Spax Origdesc

Cite This Page

Bahls, L. (2011). Stauroneis pax. In Diatoms of North America. Retrieved April 21, 2024, from https://diatoms.org/species/stauroneis_pax


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