• Category
  • Length Range
    12-18 µm
  • Width Range
    4.8-6.2 µm
  • Striae in 10 µm



Valves are linear-elliptical, often slightly gibbous at midvalve. Both valves have a linear axial area and transversely rectangular central area. The raphe is straight, without the terminal raphe fissures. The central and terminal raphe ends are slightly expanded externally. The central raphe ends curve toward opposite sides internally. The striae are radiate on both valves, 27-33 in 10 µm, interrupted at valve margin. One row of areolae is present on the margin of both valves. Areolae are 34-42 in 10 µm within the striae. The external openings of the areolae are isodiametric to transapically elongated.


Original Description

Valve elliptic, sides nearly parallel; striae radiate throughout, straight, non-punctate, 28-32/10 μ at ends, slightly coarser at center; central area transversely rectangular; rapheless valve: axial area narrow at ends expanding toward center to form ovoid rectangular area; length 13.5-15.1 μ, width 5.7-6.2 μ.

  • Basionym
    Achnanthes chlidanos
  • Author
    M.H.Hohn and Hellerman 1963
  • Length Range
    13.5-15.1 µm
  • Width
    5.7-6.2 µm
  • Striae in 10µm

Original Images

Orig Ill001 2
Orig Descr 2

Cite This Page

Potapova, M. (2010). Psammothidium chlidanos. In Diatoms of North America. Retrieved May 18, 2024, from https://diatoms.org/species/psammothidium_chlidanos


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