• Category
  • Diameter
    6-18 µm
  • Width Range
    2.5-6 µm
  • Striae in 10 µm
  • Synonyms
    Aulacoseira distans var. nivalis (W.Sm.) E.Y.Haw.
    Melosira distans var. nivalis (W.Sm.) Kirchner
  • Reported As
    Aulacoseira pfaffiana ((Reinsch) Krammer 1991)



Frustules are cylindrical and form short chains. Valves are 6-18 µm in diameter, with a mantle height of 2.5-6 µm. The ratio of the mantle height to valve diameter is usually less than 1, so the valves are often observed in valve view. The mantle has straight sides and the valve face is flat. Rows of mantle areolae are straight, slightly inclined to the right (dextrorse), 12-16 in 10 µm, with 2-6 elongated areolae in each row. The height of the collum is approximately 1/3 of the mantle height. The valve face is covered by large areolae, 0.5-0.9 µm in diameter. The spines are pointed and narrow with anchor-shaped ends, and originate from every pervalvar costa. The ringleiste is very shallow. There is one rimoportula on the mantle near the ringleiste.


Original Description

Frustules subcylindrical; valves sub-hemispherical,• distinctly cellulate; cellules circular; extremities of valves more or less truncate. Breadth of filament •0002" to •0007". v.v.

  • Basionym
    Melosira nivalis
  • Author
    W.Sm. in Grev. 1855
  • Length Range
    5-18 µm

Original Images

 Melosira nivalis orig illus
Melosira nivalis orig illus

Cite This Page

Potapova, M., English, J. (2011). Aulacoseira nivalis. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/aulacoseira_nivalis


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