• Category
  • Length Range
    8-16 µm
  • Width Range
    4.4-5.8 µm
  • Striae in 10 µm



Valves are elliptic-lanceolate to linear-elliptic. The raphe valve has a linear axial area, which widens toward the center of the valve, and a transversely elliptic central area. The raphe is straight, without terminal fissures. The central and terminal raphe ends are simple. The central raphe ends curve toward opposite sides internally. The rapheless valve has a wide rhomboid-lanceolate axial area. The central area is usually not differentiated from the axial area. Striae are radiate on both valves, 23-27 in 10 µm. One row of areolae is present on the mantle of both valves. The external openings of the areolae are small, circular.


Common in soft acidic waters.

Original Description

  • Basionym
    Achnanthes acidoclinata
  • Author
    Lange-Bert. in Lange-Bert. and Metzeltin 1996
  • Length Range
    8-14(16) µm
  • Width
    4-7 µm

Original Images

Achnanthes acidoclinata orig illus
Achnanthes acidoclinata  orig illus 2
Achnanthes acidoclinata  orig descr


Mar 28, 2018 - Change in name

From August 2010 until March 2018, this taxon appeared under the name Psammothidium marginulatum. It was updated to conform to Lange-Bertalot and Metzeltin (1996). - M. Potapova

Cite This Page

Potapova, M. (2010). Psammothidium acidoclinatum. In Diatoms of North America. Retrieved July 19, 2024, from https://diatoms.org/species/psammothidium_acidoclinatum


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