• Category
  • Length Range
    11.7-15 µm
  • Width Range
    5.6-6 µm
  • Striae in 10 µm
    26–28 on rapheless valve, 30–32 on raphe valve



Valves are elliptic. The raphe valve has a linear axial area and a transapically rectangular to oval central area, occupying 2/3 of the valve breadth. The raphe has proximal pores that are slightly expanded and located in grooves. The distal raphe has simple distal ends. The rapheless valve has an axial area that is narrow at the apices and widens toward the valve center, in a rhombic-lanceolate shape and occupies 2/3 of the valve breadth. Striae are slightly radiate, and more coarse on the rapheless valve as compared to the raphe valve. Areolae on the rapheless valve are visible in LM.


So far found only in oligotrophic lakes of Washington Cascade Mountains.

Original Description

  • Author
    Potapova and Enache 2013
  • Length Range
    11.7-15 µm
  • Width
    5.6-6 µm
  • Striae in 10µm
    26–28 in 10 μm on rapheless valve, 30–32 on raphe valve

Original Images

Psnivale  Orig Ill
Psnivale  Orig Descr

Cite This Page

Potapova, M. (2014). Psammothidium nivale. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/psammothidium_nivale


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