• Category
  • Length Range
    9–13 µm
  • Width Range
    5.0–5.4 µm
  • Striae in 10 µm



Valves are elliptic. Raphe valve has a narrow linear axial area and transversely rectangular, or elliptic central area. The raphe is filiform and straight with slightly expanded, almost straight or very slightly deflected external distal ends. The internal proximal raphe ends are deflected to opposite sides. The internal distal raphe ends have small helictoglossae. The rapheless valve has a narrow linear axial area and an asymmetric central area. Striae are uniseriate. Areolae are isodiametric and number 35–40 in 10 μm. The central striae have 8–9 areolae in central striae, numbering 35-40 areolae in 10 μm. The external areolae openings are very small.


Psammothidium pennsylvanicum has been found in 15 streams in north central Pennsylvania, including some affected by acid mine drainage. Conductivity in these streams ranged from 6 to 378 μS/cm, and pH from 4.0 to 7.0.

Original Description

  • Author
    Potapova 2012
  • Length Range
    9–13 µm
  • Width
    5.0–5.4 µm
  • Striae in 10µm

Original Images

Pspenn  Or Ill
Pspenn Or Descr

Cite This Page

Potapova, M. (2012). Psammothidium pennsylvanicum. In Diatoms of North America. Retrieved July 19, 2024, from https://diatoms.org/species/psammothidium_pennsylvanicum


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