Valves are linear to linear-lanceolate with capitate apices. Valves are more or less symmetric along the apical axis. The axial area is narrow. The central area is rounded and variable in size. The raphe is filiform. Proximal raphe ends are weakly expanded and deflected dorsally. Distal raphe fissures are comma-shaped and curved to the ventral side. Striae are radiate throughout.
Encyonopsis hustedtii is widespread and locally common in small streams, springs, and mossy seeps in the Northern Rockies. These waters have somewhat alkaline pH (pH 7.3-8.0) and low to moderate concentrations of dissolved solids (255-411 µS/cm).
Encyonopsis hustedtii is one of many small-celled Encyonopsis and Encyonema species in the Northern Rockies (see plate below). Some of these may be ecomorphs of established species. All of these may be found in Krammer (1997) and Bahls (2013).
Valves linear to linear-lanceolate, not or scarcely dorsiventral. Apices capitate. Valve length 14.4–19.6 µm; valve width 3.3–4.0 µm. Axial area narrow. Central area rounded, variable in size. Raphe filiform, proximal ends unexpanded, deflected dorsally. Distal raphe fissures comma-shaped, curved to the ventral side. Striae weakly radiate throughout, 23–26 in 10 µm.
Bahls, L. (2013). Encyonopsis hustedtii. In Diatoms of North America. Retrieved October 14, 2024, from https://diatoms.org/species/encyonopsis_hustedtii
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Encyonopsis hustedtii 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.