• Category
  • Length Range
    25.0–43.0 µm
  • Width Range
    7.0–8.0 µm
  • Striae in 10 µm
    Dorsal: 12–13 at the center, 14–15 at the ends; ventral: 13–15 at the center, 15–17 at the ends
  • Synonyms
    Encyonema norvegica (Grunow) Bukht. 1995



Valves moderately dorsiventral with moderately rounded apices. Dorsal margin moderately arched, with most prominent dorsal arching at the lower limits of the valve size range. Ventral margin slightly tumid or slightly concave at valve center, giving the margin a slightly triundulate or biundulate appearance. Axial area narrow and central area asymmetric, with a slightly or moderately rounded central area on the dorsal side of the valve. External areolae generally dumbbell shaped, but may be bent into V- or Y-shapes, especially at the valve center. Striae slightly radiate at valve center and becoming parallel, or slightly convergent near the apices. Internally, alveoli formed by connected rectangular openings resembling a string of beads. Transapical costae are broad and not prominent. Raphe very slightly dorsally displaced with dilated external proximal raphe ends. Internally, proximal raphe ends strongly curved dorsally and raphe terminating distally in a small helictoglossae.


Original Description

  • Basionym
    Cymbella norvegica
  • Author
    Grunow in Schmidt et al. 1875

Original Images

Plate 10

Cite This Page

Graeff, C. (2012). Encyonema norvegicum. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/encyonema_norvegicum


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