• Category
  • Length Range
    13.1-20.6 µm
  • Width Range
    3.0-3.8 µm
  • Striae in 10 µm
  • Synonyms
    Encyonopsis microcephala var. robusta (Hust.) Krammer 1997
    Cymbella microcephala var. robusta Hust. 1939



Valves are linear to linear-lanceolate and not or weakly dorsiventral. Apices are capitate. The axial area is narrow. The central area is small and rounded. The raphe is filiform and straight with unexpanded proximal ends that are deflected dorsally. Distal raphe fissures are comma-shaped and curved to the ventral side. Striae are weakly radiate throughout.


Encyonopsis robusta is widespread and locally common in small streams, springs, and mossy seeps in the Northern Rockies. These waters typically have somewhat alkaline pH and low to moderate concentrations of dissolved solids. Encyonopsis robusta may occupy the same habitats as E. hustedtii.

Blakiston  Beaver  Pond  A 4
Credit: Barb Johnston, Parks Canada
Blakiston Beaver Pond A, Waterton Lakes National Park, Alberta: home of Encyonopsis robusta.

Original Description

  • Basionym
    Cymbella microcephala fo. robusta
  • Author
    Hust. 1939

Cite This Page

Bahls, L. (2013). Encyonopsis robusta. In Diatoms of North America. Retrieved May 25, 2024, from https://diatoms.org/species/encyonopsis_robusta


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