• Category
  • Length Range
    16-18 µm
  • Width Range
    3.0-3.2 µm
  • Striae in 10 µm



Valves are triundulate with rostrate to subcapitate ends. The central area is expanded laterally with 2-4 shortened striae at the valve margin. The striae are radiate near the center of the valve becoming parallel near the ends. Two to three rows of annulae are at each apex of the valve.


Original Description

Linear, dreiwellig, Enden gerundet. Lang 17-25µ, breit 4,5-5µ. 12-14 Streifen in 10 µ, gebogen, die konvexe Seite den Enden zugewandt, die mittelsten stark verkürzt, so daB sich die schmale, lineare Längsarea in der Mitte fast bis zum Rande erweitert. Die mittleren Streifen konvergierend , gegen die Enden senkrecht zur Raphe.

  • Basionym
    Navicula ignota
  • Author
    Krasske 1932
  • Length Range
    17-25 µm
  • Width
    4.5-5 µm
  • Striae in 10µm

Original Images

Gignota  Orig Ill
Gignota  Orig Descr

Cite This Page

Lowe, R. (2011). Geissleria ignota. In Diatoms of North America. Retrieved June 20, 2024, from https://diatoms.org/species/geisleria_ignota


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