• Category
  • Length Range
    13.7-26.1 µm
  • Width Range
    3.3-4.4 µm
  • Striae in 10 µm



Valves are lanceolate in smaller specimens, to rhombic-lanceolate in larger specimens. Apices are rostrate to subcapitate in smaller specimens. The apices of larger specimens are not protracted. The axial area is narrow. A central area is absent. The raphe is filiform with weakly expanded proximal ends that are deflected slightly toward the dorsal margin. Raphe branches are somewhat bowed and concave to the dorsal margin. Striae are parallel near the valve center to moderately radiate near the apices.


Encyonopsis neerlandica is widely distributed and locally abundant in mountain lakes in the Northern Rockies. At collection sites with water quality data, pH ranges from 6.7 to 7.2 and specific conductance from 14 to 250 μS/cm. In Europe, Van de Vijver et al. (2012) described this species from oligotrophic to mesotrophic, oxygen-rich and circumneutral moorland pools with low to moderate conductivity.

Hoodoo  Lake 1
Credit: Google Earth
Hoodoo Lake, Mineral County, Montana: home of Encyonopsis neerlandica.

Original Description

Valves weakly (smaller specimens) to moderately (larger specimens) dorsiventral, narrowly lanceolate (never linear) with convex dorsal margin and slightly convex ventral margin. Apices protracted, acutely rounded, rostrate to subcapitate. Valve dimensions (n = 25): length 15–26 μm, width 3.5–4.5 μm, valve length/width ratio 4.2–6.3. Sternum very narrow, linear. Central area absent, striae rarely occur in central area, more distantly spaced. Raphe filiform, curved to the ventral side but with dorsally deflected central raphe endings terminating in inconspicuous central pores. Transapical striae weakly radiate to moderately radiate near the apices, almost equally spaced throughout the entire valve, dorsally 25–28, ventrally 24–26 in 10 μm although in some cases up to 30 striae can be found near the apices. Areolae not discernible in LM.

  • Author
    Van de Vijver et al. 2012
  • Length Range
    15-26 µm
  • Width
    3.5-4.5 µm
  • Striae in 10µm

Original Images

Encyonopsis neerlandica orig illus
Encyo Neerlandica Origdesc002

Cite This Page

Bahls, L. (2013). Encyonopsis neerlandica. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/encyonopsis_neerlandica


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