• Category
  • Length Range
    8-24 µm
  • Width Range
    1.7-2.6 µm
  • Striae in 10 µm
    17-23 in the center valve
  • Synonyms
    Eunotia paludosa var. trinacria (Krasske) Nörpel and Alles in Alles et al. 1991



Valves are elongate-triangular, becoming more linear in larger specimens. Ventral margins are straight to weakly concave. Dorsal margins are slightly convex, with a slight central undulation. Valve ends are weakly subcapitate, subrostrate and not set off, or only slightly set off, from the main part of the valve. Helitoglossae are located close to the apices. Striae are parallel. The areolae are unresolved in the LM. Frustules are rectangular in girdle view.


Found in streams, wetwalls, waterfalls, and sink holes, often associated with bryophytes.

Original Description

  • Author
    Krasske 1929
  • Length Range
    4-10 µm
  • Width
    2-4 µm
  • Striae in 10µm

Original Images

Eunotia trinacria orig illus
Eunotia Trinacria  Orig Descr

Cite This Page

Furey, P. (2012). Eunotia trinacria. In Diatoms of North America. Retrieved May 29, 2024, from https://diatoms.org/species/eunotia_trinacria


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