Diatoms of North AmericaDiatoms of North America

Stauroneis absaroka

Bahls 2010

Stauroneis Absaroka Guide
  • Category
    Symmetric Biraphid
  • Length Range
    43-75 µm
  • Width Range
    10.1-14.7 µm
  • Striae in 10 µm
    17-19

Identification

Stauroneis absaroka LM6 Stauroneis absaroka LM5 Stauroneis absaroka LM4 Stauroneis absaroka LM3 Stauroneis absaroka LM2 Stauroneis absaroka LM1
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Description

Valves are lanceolate with subrostrate to subcapitate apices. The axial area is broad, often with an irregular border formed by the ends of striae, widening gradually towards the central area. The central area is a very broad stauros, widening markedly toward the valve margins. Curved striae border the stauros. Shortened striae have not been observed in the central area. The raphe branches are moderately lateral. Proximal raphe ends are strongly curved and tipped with distinctly inflated, drop-like central pores. Striae are radiate throughout and curved about the central area. Striae puncta are distinct and number 22-26 in 10 µm.

Autecology

Stauroneis absaroka has been recorded from five lakes and ponds in southwest Montana. The pH of these waters ranges from 6.1 to 7.8 and specific conductance ranges from 21 to 41 µS/cm. This taxon is uncommon and only a minor component of the diatom assemblage at each location where it was found.

Bloody Dick Pond 3
Credit: Loren Bahls
Bloody Dick Pond #3, Beaverhead County, Montana: home of Stauroneis absaroka.

Original Description

Valves lanceolate with subrostrate to subcapitate ends. Length 43-75 µm, width 10.1-14.7 µm. Axial area wide, often with an irregular border, expanding gradually toward the central area. Central area a very broad butterfly-shaped fascia, widening markedly toward the valve margins. Shortened striae not observed in the central area. Raphe fissures moderately lateral, proximal endings strongly curved and tipped with distinctly inflated, drop-like central pores. Striae curved and radiate throughout, 17-19 in 10 µm. Striae puncta distinct, 22-26 in 10 µm. For measurements, n = 14 valves.

  • Author
    Bahls 2010
  • Length Range
    43-75 µm
  • Width
    10.1-14.7 µm
  • Striae in 10µm
    17-19

Original Images

Sabsaroka Origimag
Sabsaroka Origdesc

Cite This Page

Bahls, L. (2011). Stauroneis absaroka. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/stauroneis_absaroka

Responses

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