• Category
  • Length Range
    11.5-22 µm
  • Width Range
    5.9-7.6 µm
  • Striae in 10 µm
  • Synonyms
    Achnanthes flexella var. alpestris Brun
    Achnanthes alpestris (Brun) Lange-Bert. and Metzeltin
    Eucocconeis flexella var. alpestris (Brun) Hust.



Valves are rectangular-elliptical with slanted ends or in the shape of a parallelogram, often twisted. The raphe valve has an oblique narrow linear or slightly sigmoid axial area and a transversely rectangular central area. The raphe is slightly sigmoid with terminal raphe fissures curved to opposite directions. The rapheless valve has a narrow linear or slightly sigmoid axial area, which is also often oblique. The central area on rapheless valve is large, hexagonal to diamond-shaped or rounded. The striae are punctate, slightly radiate, or radiate on one side of the valve, but parallel to slightly convergent on the other side, 25-30 in 10 μm.


Original Description

Var. : Alpestris. Nova, Pl. III, fig. 26. — L. 15 à 45 μ. — F.v. courbée, ventrue, à terminaisons larges, arrondies et un peu capitulées ; stries subtiles; nœud large, ordinairement conique. F.v. à simple courbure. Sources des Alpes et de la région montagneuse; assez commune.

  • Basionym
    Achnanthes flexella var. alpestris
  • Author
    Brun 1880
  • Length Range
    15-45 µm

Original Images

Eucocconeis alpestris orig illus 2
Orig Descr 6

Cite This Page

Potapova, M. (2010). Eucocconeis alpestris. In Diatoms of North America. Retrieved July 15, 2024, from https://diatoms.org/species/eucocconeis_alpestris


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