• Category
  • Length Range
    15.5-36.6 µm
  • Width Range
    4.9-7.1 µm
  • Striae in 10 µm
  • Synonyms
    Anomoeoneis styriaca (Grunow) Hust. 1930
  • Reported As
    Anomoeoneis styriaca (Patrick and Reimer 1966, p. 382, plate 33, fig. 15)



This page is being evaluated and may be updated with a new name following Van de Vijver et al. (2021).

Valves are lanceolate with rounded, unprotracted apices. The axial area is narrow. The central area is elliptical, apically elongated, with a middle constriction in larger valves. Proximal raphe ends are weakly expanded and close in small valves, becoming increasingly distant in larger valves. Striae are radiate. Areolae are transapically elliptic near the axial area and bacilliform towards the valve margins. Areolae are irregularly spaced, creating a pattern of undulating longitudinal lines.


Specimens of B. styriaca pictured on this website are from Bent Flat Fen and Johns Lake, both in Flathead County, northwest Montana. The pH of Bent Flat Fen is 7.40 and specific conductance is 460 µS/cm. The pH of Johns Lake is 7.24 and specific conductance is 30 µS/cm. Lange-Bertalot & Moser (1994) report that B. styriaca is widely distributed and locally abundant in northern and alpine regions of the Northern Hemisphere and that it is a good indicator of oligotrophic and oligosaprobic waters.

Johns  Lake  Gnp  Hikespeak Com
Credit: Hikespeak.com
Johns Lake, Glacier National Park, Montana: home of A. rostellata

Original Description

  • Basionym
    Navicula styriaca
  • Author
    Grunow in Van Heurck 1880

Cite This Page

Bahls, L. (2014). Brachysira styriaca. In Diatoms of North America. Retrieved February 28, 2024, from https://diatoms.org/species/brachysira_styriaca


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