• Category
  • Length Range
    55-82 µm
  • Width Range
    11.0-16.8 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis anceps (Krammer and Lange-Bertalot 1986)
    Stauroneis anceps (Patrick and Reimer 1966)
    Stauroneis anceps (Camburn and Charles 2000)



Valves are linear-elliptic-lanceolate with abruptly protracted, rostrate to subcapitate apices. The axial area is narrow and nearly linear, widening a bit near the central area. The central area is shaped like a bow tie and is wider near the valve margins. Shortened striae are occasionally present in the central area. The raphe is moderately lateral. Proximal raphe ends are nearly straight, terminated by small, weakly inflated pores. Striae are radiate throughout. Areolae are variably spaced and number 18-25 in 10 µm.

Note that previous floras (Krammer and Lange-Bertalot 1986, Patrick and Reimer 1966, Camburn and Charles 2000) did not include S. amphicephala, but treated it under a very broad concept of S. anceps.


Stauroneis amphicephala is widely distributed in the Northern Rockies in habitats ranging from small ponds and wetlands to large lakes. pH in these waters ranges from 6.0 to 8.6 and specific conductance ranges from 35 to 140 µS/cm. Van de Vijver et al. (2004) report Stauroneis amphicephala as widely distributed in the Arctic in a variety of standing waters with a pH range of 6.1 to 8.1 and specific conductance values ranging from near 0 to 280 µS/cm. Such conditions are very similar to those recorded in the Northern Rockies.

Cut  Bank  Pond  Gnp
Credit: Loren Bahls
Cut Bank Pond, Glacier National Park, Montana: home of Stauroneis amphicephala.

Original Description

  • Author
    Kütz. 1844
  • Length Range
    60 µm
  • Width
    12-14 µm

Original Images

Stauroneis Amphicephala  Orig Ill
Stauroneis Amphicephala  Orig Descr

Cite This Page

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


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