• Category
  • Length Range
    20-47 µm
  • Width Range
    6.3-8.2 µm
  • Striae in 10 µm



Valves are linear to biundulate, with parallel sides in smaller specimens to slightly concave sides in larger specimens. Apices are cuneate and rounded. The axial area is narrow, gradually widening toward the small elliptic central area. The raphe is weakly lateral. The proximal raphe ends curve toward the primary side of the valve. Distal raphe ends are hooked toward the secondary side. Striae are parallel in the middle, become weakly radiate, and then parallel again at the apices. Areolae are coarse and number 18-20 in 10 µm.

This taxon may be conspecific with Navicula natchikae, described from Kamchatka (Petersen 1946).


There are 17 records of Boreozonacola olympica in the Montana Diatom Collection, all from streams, lakes, ponds, and fens in northern Idaho and western Montana. The pH of these waters ranges from 6.0 to 7.8 and specific conductance ranges from 16 to 71 µS/cm. This taxon was described from springs in Olympic National Park, Washington (Sovereign 1963) (elevation 1676 meters, pH 6.8). It has also been repored from Adak Island, Alaska (Hein 1990) .

No  Name  Lake  Gnp
Credit: Loren Bahls
No Name Lake, Glacier National Park, Montana: home of Boreozonacola olympica.

Original Description

Valves linear with cuneate rounded ends, margins slightly triundulate, 21-47 µ long, 6-8 µ wide. Axial area narrow lanceolate, central area irregular elliptical. Raphe threadlike, slightly curved, central pores distant. Striae radial infrequently becoming parallel at the ends, 17-19 in 10 µ, plainly punctate, the puncta spaced about 20 in 10 µ.

  • Basionym
    Navicula pseudosilicula var. olympica
  • Author
    Sovereign 1963
  • Length Range
    21-47 µm
  • Width
    6-8 µm
  • Striae in 10µm

Original Images

Navicula pseudosilicula var. olympica orig illus
Navicula pseudosilicula var. olympica orig descr

Cite This Page

Bahls, L. (2011). Boreozonacola olympica. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/boreozonacola_olympica


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