• Category
  • Length Range
    124-213 µm
  • Width Range
    21-33 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis phoenicenteron f. gracilis (Patrick and Reimer 1966)
    Stauroneis phoenicenteron f. gracilis (Camburn and Charles 2000)
    Stauroneis regina (Bahls 2010)



Valves are narrowly lanceolate with subtly protracted apices. The axial area is linear and two to three times wider than the raphe. The stauros is rectangular, often widening slightly near the valve margins. Short striae are absent from the stauros. The raphe is lateral with curved and inflated proximal ends. Terminal raphe fissures are hooked toward the secondary side. Striae are radiate throughout. Areolae are relatively coarse and number 14-18 in 10 µm.


Stauroneis supergracilis is widely distributed in lakes, ponds, and wetlands in the Northern Rockies. The pH of these waters ranges from 5.5 to 8.6 (mean pH = 6.7) and specific conductance ranges from 7 to 168 µS/cm (mean SC = 63 µS/cm). Van de Vijver et al. (2004) report this species from the sub-Antarctic, where it was found in a large shallow pool with slightly acid pH (6.6) and low specific conductance (<100 µS/cm).

Bloody  Dick  Pond 2 2
Credit: Loren Bahls
Bloody Dick Pond No. 2, Beaverhead County, Montana: home of Stauroneis supergracilis.

Original Description

Differential diagnosis compared to Stauroneis gracilis Ehrenberg: Valves relatively narrow-lanceolate with hardly protracted, simply bluntly rounded ends, valves gradually attenuating towards the ends (and not linear- or elliptic-lanceolate with protracted, subrostrate ends). Length 120-140 µm, breadth 20-22 µm (and not 75-120 µm and 15-20 µm). Raphe distinctly lateral with central external endings significantly curved with moderately deflected pores towards the secondary side of the valve (as in St. gracilis). Axial area almost linear and moderately broad, hardly widened near the central area. Central area forming a somewhat irregular fascia as to breadth, moderately widened towards the margins. Striae strongly radiate throughout, 16-17 in 10 µm. Puncta in the striae not very densely spaced, 17-18 (and not 18-21) in 10 µm. In the central area, sometimes (a few) irregularly shortened striae are present.

  • Author
    Van de Vijver and Lange-Bert. 2004
  • Length Range
    120-140 µm
  • Width
    20-22 µm
  • Striae in 10µm

Original Images

Stsupergracilis Origimag
Stsupergracilis Origdesc

Cite This Page

Bahls, L. (2012). Stauroneis supergracilis. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/stauroneis_supergracilis


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