• Category
  • Length Range
    215-386 µm
  • Width Range
    38-60 µm
  • Striae in 10 µm
    12-14

Identification

Description

Valves are lanceolate and very large with blunt, broadly rounded apices. The axial area is moderately broad and linear. The central area is a rectangular stauros, often narrowing somewhat toward the valve margins. Short striae may be present in the central area. External raphe fissures are lateral. Proximal raphe ends are straight and somewhat inflated. Striae are radiate throughout. Areolae are coarse and number 11-14 in 10 µm.

Autecology

Stauroneis rex is widely distributed in ponds and small lakes in the Northern Rockies. These waters tend to be alkaline (mean pH = 7.8) with moderate concentrations of electrolytes (mean specific conductance = 194 µS/cm). In contrast, Stauroneis phoenicenteron prefers circumneutral waters (mean pH = 7.1) with low concentrations of electrolytes (mean specific conductance = 34 µS/cm).

Handkerchief  Lake 1
Credit: Loren Bahls
Handkerchief Lake, Flathead County, Montana: type locality of Stauroneis rex.

Original Description

Valves are very large and broadly lanceolate with blunt, broadly rounded ends. Length 215-386 µm, width 38-60 µm. Length to width ratio: 5.6-6.5. Axial area moderately broad and linear. Central area a rectangular fascia, narrowing somewhat toward the valve margins. Shortened striae may be present. External raphe fissures lateral, proximal endings somewhat inflated and straight. Terminal raphe fissures hooked, opening toward the secondary side. Striae radiate throughout, 12-14 in 10 µm. Striae puncta coarse, 11-14 in 10 µm. For measurements, n = 68 valves.

  • Author
    L.L.Bahls 2010
  • Length Range
    215-386 µm
  • Width
    38-60 µm
  • Striae in 10µm
    12-14

Original Images

Srex Origimage1
Srex Origimage2
Srex Origdesc

Cite This Page

Bahls, L. (2011). Stauroneis rex. In Diatoms of North America. Retrieved June 22, 2018, from https://diatoms.org/species/stauroneis_rex

Responses

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