Identification

Description

Valves are linear in small specimens to lanceolate in larger specimens, with protracted and broadly rounded apices. The axial area is narrow and widens slightly near the central area. The stauros is narrow, somewhat expanded toward the valve margins, and occasionally contains short striae at the margins. Raphe branches are lateral. Proximal raphe ends are inflated and curved. Terminal raphe fissures are hooked. Striae are radiate throughout. Areolae number 18–22 in 10 µm.

Autecology

Stauroneis subborealis has been found in a few fens, ponds, and small lakes in western Montana. The pH of these waters ranges from 6.2 to 9.1 and specific conductance ranges from 10 to 257 µS/cm.

014 11 A 1
Credit: Loren Bahls
Drosera Fen, Indian Meadows Research Natural Area, Helena National Forest, Montana: type locality for Stauroneis subborealis.

Original Description

Valves are linear in small specimens to lanceolate in larger specimens, with protracted and broadly rounded apices. Length 46–142 µm, width 9–24 µm. Length to width ratio: 4.9-6.6. Axial area narrow, widening slightly near the central area. Transverse fascia narrow, somewhat expanded toward the valve margins, occasionally containing short striae. Raphe fissures lateral, proximal endings inflated and curved. Terminal raphe fissures hooked. Striae radiate throughout, 17–20 in 10 µm. Striae puncta 18–22 in 10 µm. For measurements, n = 31 valves.

  • Author
    L.L.Bahls 2010
  • Length Range
    46-142 µm
  • Width
    9-24 µm
  • Striae in 10µm
    17-20

Original Images

Ssubbor Origimag1
Ssubbor Origimag2
Ssubbor Origdesc

Cite This Page

Bahls, L. (2011). Stauroneis subborealis. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/stauroneis_subborealis

Responses

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