• Category
  • Length Range
    14.5-47.5 µm
  • Width Range
    2.2-3.7 µm
  • Striae in 10 µm
    18-22 in the center valve, 20-24 ends



The dorsal margin is convex and the ventral margin is concave. Valves are strongly arched, more so in larger specimens. For most of the length of the valve, the margins are similar in shape and equally spaced from one another. The apices are rounded, protracted and dorsally recurved. The helictoglossae are located close to the apices. The distal raphe ends curve onto the valve face, extending a little less than halfway to the dorsal margin and then curving back slightly toward the center of the valve face. Striae are evenly spaced, and parallel along the length of the valve, becoming radiate at the apices. Areolae are 40 in 10 µm. One apical rimoportula is present, just dorsal of the midway point on the valve apex. The external expression of the rimoportula is similarly placed (see SEM image). The internal expression of the areolae are round and areolae aligned at almost the same level as the inner valve surface.

Historically, there has been taxonomic confusion between E. steineckei Peterson and E. nymanniana. Eunotia steineckei is considered to be a subjective synonym of E. nymanniana (see discussions in Furey et al. 2011, Lange-Bertalot et al. 2011, and Mayama 1997). The original description of E. nymanniana includes two diagrams (Grunow 1881, Figs 34: 8,10). The image on the left (Fig 34: 8) was lectotypified by Mayama (1997) and the image on the right is conspecific with E. neocompacta Mayama in Mayama & Kawashima (1998).


Found in streams and wet walls, often associated with bryophytes.

Original Description

  • Author
    Grunow 1881

Original Images

Eunotia  nymanniana orig illus
Eunotia nymanniana orig illus 2

Cite This Page

Furey, P. (2012). Eunotia nymanniana. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/eunotia_nymanniana


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