• Category
  • Length Range
    38-85 µm
  • Width Range
    19-31 (girdle view) µm
  • Striae in 10 µm
  • Reported As
    Entomoneis paludosa var. subsalina (Krammer and Lange-Bertalot 1986)



Frustules almost always come to rest in girdle view, a view which is dominated by two highly arched bilobate keels, one on each valve. The keels are slightly torsioned so that the lobes are not all in focus at one time. Lobe margins are flattened in large specimens and more rounded in smaller specimens. Several girdle bands are present and form a crossing, sigmoid pattern that is most evident in small specimens. The junction line between the valve and the keel contains a single bulge, which is flattened and smoothly rounded in large specimens but more angular in smaller specimens. The junction line lacks prominent spots or thickened ribs. Striae on the valve face continue onto the keel without differentiation. Areolae within a stria on both the valve face and the keel are very fine and number approximately 30 in 10 µm.


With 264 records in the Montana Diatom Collection, Entomoneis paludosa is the most frequently occurring species of this genus on the Northwestern Great Plains (Montana, North Dakota, South Dakota, Wyoming). The preferred habitat of this epipelic diatom is muddy streams with a mean pH of 8.6, a mean specific conductance of 3279 µS/cm, and elevated concentrations of sodium and sulfate. Frequent diatom associates of E. paludosa in these habitats are Cymbella pusilla, Nitzschia reversa, Pleurosigma delicatulum, Biremis circumtexta, Nitzschia filiformis, Navicula erifuga, Tabularia fasciculata, and Nitzschia aurariae. Patrick and Reimer (1975) report this species as widely distributed in the United States in waters with moderately high conductivity.

Little  Dry  Creek 2
Credit: Loren Bahls
Little Dry Creek, Garfield County, Montana: home of Entomoneis paludosa.

Original Description

  • Basionym
    Amphiprora paludosa
  • Author
    W.Sm. 1853

Original Images

Entomoneis paludosa orig illus
Entomoneis Paludosa  Orig Descr

Cite This Page

Bahls, L. (2012). Entomoneis paludosa. In Diatoms of North America. Retrieved April 14, 2024, from https://diatoms.org/species/entomoneis_paludosa


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