• Reported As
    Neidium binode (Patrick and Reimer, pg. 404, Pl. 37, Fig. 6)



Valves are linear-elliptical and biundulate, with constricted central margins and rostrate apices. Striae are uniseriate, coarse, and parallel at the central area becoming weakly radiate near the apices. Areolae are transapically elongate near the raphe, becoming circular near the margin of the valve. A narrow longitudinal canal borders the valve margin. The central area is asymmetric and oval. The axial area is narrow and linear. The raphe is straight. The proximal raphe ends are straight, or deflected slightly to the primary side.

Note that this taxon was described (Krammer 1985) based on Neidium binodis sensu Germain 1981, as distinct from N. binodis (Ehrenberg) Hustedt. The original material of N. binodis (Ehrenberg) Hustedt, however, has not been examined and such work may change the standing of these two species.

Also note that Patrick and Reimer (1966) illustrate a taxon that conforms to N. binodiformis, but is named Neidium binode. It is likely that many of the North American reports do not distinguish, or confuse, these two species.


Neidiomorpha binodiformis was found in a benthic collection from Cold Creek, San Bernadino County in southern California. It was also found in samples from the Spirit Lake fish hatchery, Dickinson County, Iowa. According to Cantonati et al. (2010), xxxxxxxxxxxxxxxx

Original Description

  • Basionym
    Neidium binodiforme
  • Author
    Krammer 1985
  • Length Range
    16-33 µm
  • Width
    5-8 µm
  • Striae in 10µm

Original Images

Neidium Binodeforme  Krammer  Lm
Neidium Binodeforme  Krammer  Sem
Neidium Binodeforme  Krammer Orig

Cite This Page

Mendoza, S. (2015). Neidiomorpha binodiformis. In Diatoms of North America. Retrieved July 20, 2018, from https://diatoms.org/species/neidiomorpha_binodiformis


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