• Category
  • Length Range
    53-64 µm
  • Width Range
    9.0-12.0 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis gracilior "Zackenberg" (Van de Vijver et al. 2004)



Valves are lanceolate to rhombic-lanceolate with gradually narrowed capitate apices. Raphe branches are moderately lateral, becoming filiform at the distal and proximal ends. Proximal raphe ends are straight and not expanded. The axial area is narrow and linear, barely wider than the raphe, and expands slightly at the central area. The central area is a rectangular stauros. Striae are radiate throughout. Areolae are round to transapically oblong, irregularly spaced, and number 20-24 in 10 µm.


Stauroneis pikuni is widely distributed in lakes and ponds throughout the Northern Rockies, but is rarely found in abundance. In waters where Stauroneis pikuni occurs, pH ranges from 6.6 to 7.3 and specific conductance ranges from 8 to 71 µS/cm. Van de Vijver et al. (2004) reported this taxon (as Stauroneis gracilior "Zackenberg") from the Zackenberg area of East Greenland.

Loren At  Marinas  Pond  Glacier  National  Park
Credit: Marina Potapova
Loren Bahls at Two Medicine Campground Pond, Glacier National Park, Montana: type locality for Stauroneis pikuni.

Original Description

Valves lanceolate with gradually narrowed capitate to subcapitate ends. Length 53-64 µm, width 9-12 µm. Raphe fissures moderately lateral, becoming filiform at the distal and proximal ends. Proximal raphe endings straight, pores not inflated or deflected. Axial area narrow and linear, barely wider than the raphe, flaring slightly at the central area. Central area a narrow rectangular fascia. Striae radiate throughout, 24-28 in 10 µm. Striae puncta fine, round to oblong, and irregularly spaced, 20-24 in 10 µm. For measurements, n = 22 valves.

  • Author
    Bahls 2010
  • Length Range
    53-64 µm
  • Width
    9-12 µm
  • Striae in 10µm

Original Images

Spikuni Origimag1
Spikuni Origimag2
Spikuni Origdesc

Cite This Page

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


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