• Category
  • Length Range
    29-45 µm
  • Width Range
    7.0-11.4 (valve height, including keel) µm
  • Striae in 10 µm
  • Synonyms
    Entomoneis paludosa var. punctulata (Grunow) Czarn. and Reinke 1982



Frustules are very lightly silicified and come to rest primarily in girdle view, a view which is dominated by two highly arched bilobate keels, one on each valve. The keel lobes are broadly rounded and the keels are only slightly torsioned so that both lobes are more or less in focus at the same time. A row of dots, that may be determined to be fibulae, follow the contour of each lobe a short distance from the keel margin. The short, curved junction line between valve face and keel is restricted to a terminal portion of each lobe of the keel. The cingulum is composed of five or six open bands. Striae are very faint and continuous from the valve face onto the keel without differentiation. The fine structure of the striae cannot be resolved in LM.


There is only one record of Entomoneis punctulata in the Montana Diatom Collection, that from the Redwater River near Circle, Montana. This taxon is likely overlooked in strewn mounts because of its weakly silicified frustules and faint markings. E. punctulata is widespread in marine to brackish waters of the Arctic and temperate regions, including the Baltic Sea (Witkowski et al. 2000). Osada and Kobayasi (1990) report it from several river estuaries in Japan.

Redwater  River
Credit: Loren Bahls
Redwater River, McCone County, Montana: home of Cymbella hustedtii

Original Description

  • Basionym
    Amphiprora paludosa var. punctulata
  • Author
    Grunow in Cleve and Grunow 1880
  • Length Range
    46-50 µm

Original Images

Entomoneis punctulata orig illus
Entomoneis Punctulata  Orig Descr

Cite This Page

Bahls, L. (2012). Entomoneis punctulata. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/entomoneis_punctulata


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