• Category
  • Length Range
    22.6-32.9 µm
  • Width Range
    9-10.3 µm
  • Striae in 10 µm
    10-12 in the center of the valve, 12-15 near the ends
  • Synonyms
    Encyonema caespitosum var. auerswaldii (Rabenh.) van Heurck 1882
    Cymbella ventricosa var. auerswaldii (Rabenh.) F.Meister 1912
    Cymbella caespitosum var. auerswaldii (Rabenh.) A.Cleve 1955



Valves are strongly arched dorsally and slightly tumid ventrally, with rounded ends. In larger specimens, the ends may be slightly rostrate. Dorsal striae are parallel near the center, becoming radiate near the ends. Ventral striae are slightly radiate. Areolae in each stria are clearly visible and number approximately 25 in 10 µm. The axial area is slightly lanceolate; it is narrow near the ends and slightly expanded and rounded in the central area. The raphe is broad and lateral. The proximal raphe ends are dorsally deflected, while the distal raphe ends are ventrally deflected.

Living cells form mucilage tubes, where they live as colonies inside the tubes.

The lectotype of E. auerswaldii was examined and compared to types of E. prostratum and E. cespitosum (Silva et al. 2013). They report that specimens of E. prostratum are broader than E. cespitosum (16–24.7 μm versus 9.6–12 μm). The maximum length of E. prostratum was reported as 88 μm, and the maximum length of E. cespitosum was reported as 47 μm.


Encyonema auerswaldii often grows as an epiphyte. It forms long, branching mucilage tubes. Encyonema auerswaldii is common in freshwaters across the US.

Encyonema A
Credit: R. Lowe
Periphyton from the Eel River, California, showing Encyonema auerswaldii attached to the green alga, Cladophora.

Original Description

  • Author
    Rabenh. 1853
  • Length Range
    30 µm
  • Striae in 10µm

Original Images

Encyonema auerswaldii orig illus
Encyonema Orig

Cite This Page

Lowe, R. (2015). Encyonema auerswaldii. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/encyonema_auerswaldii


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