• Category
  • Length Range
    19-30 µm
  • Width Range
    6.5-7.5 µm
  • Striae in 10 µm
    16-18 in middle of dorsal side, 15-18 in middle of ventral side
  • Reported As
    Encyonema hebridicum (Krammer 1997, Taf. 123, Fig. 9)



Valves are moderately to strongly dorsiventral. The dorsal margin is arched and the ventral margin is slightly convex. The apices are protracted and slightly capitate. The raphe is straight, with slightly dorsally deflected proximal ends and strongly ventrally deflected distal ends. The axial area is narrow, with the central area slightly expanded. A stigma is absent. Striae are slightly radiate in the center valve, becoming nearly parallel at the apices.

Janus cells are observed in this taxon. Such frustules have valves of distinctly different stria density on each valve. Janus cells are illustrated in Figures 11a and 11b in the plate from the original publication (Winter and Bahls 2013).

This taxon was illustrated in Krammer (1997) within the images of E. hebridicum, leading to later misidentification in North American material. This taxon was also referred to as ‘Encyonema sp. 1 MONTANA HAMSHER’.


The highest abundance of E. hamsherae is from sites on small headwater streams suggesting a preference for cold, nutrient-poor waters. In general, Encyonema hamsherae is found at elevations ranging from about 1000 to 2100 m. Encyonema hamsherae appears to prefer moderate levels of alkalinity and dissolved solids.

Original Description

Valves moderately to strongly dorsiventral. Dorsal margin arched, ventral margin slightly convex, ends protracted and slightly capitate. Raphe straight, proximal ends slightly dorsally deflected, distal ends strongly ventrally deflected. Axial area narrow, central area slightly expanded, stigma absent. Striae slightly radiate in center becoming nearly parallel at ends. Valve length 19-30 µm, valve width 6.5-7.5 µm, dorsal central striae (14) 16-18 in 10 µm, ventral central striae (11) 15-17 (18) in 10 µm.

  • Author
    Winter and Bahls 2012
  • Length Range
    19-30 µm
  • Width
    6.5-7.5 µm
  • Striae in 10µm
    (14) 16-18 in middle of dorsal side, (11) 15-17 (18) in middle of ventral side

Original Images

Original Plate

Cite This Page

Winter, D. (2012). Encyonema hamsherae. In Diatoms of North America. Retrieved July 24, 2024, from https://diatoms.org/species/encyonema_hamsherae


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