• Category
  • Length Range
    60-79 µm
  • Width Range
    14.8-17.8 µm
  • Striae in 10 µm
  • Reported As
    Neidium kozlowi var. elliptica (Foged 1981, p. 135, plate XXVI, fig. 6)
    ?Neidium kozlowii (Metzeltin et al. 2009, p. 336, plate 102, figs. 2-7; not plate 103, figs. 7-11)



Valves are lanceolate with broadly rounded and unprotracted or very weakly protracted apices. A longitudinal line is evident along each margin. The axial area is straight, about three times wider than the raphe, becoming somewhat wider near the central area. The central area is wide, rectangular in shape and crosses the valve diagonally. It is bordered by short faint striae along the valve margins. The raphe is lateral, becoming filiform at the proximal ends, which are hooked sharply in opposite directions. Striae are oriented diagonally across the valve face. Areolae number 20-24 in 10 µm.


Besides three lakes in the Bob Marshall Wilderness of northwestern Montana, Neidium bobmarshallensis has been recorded from Logging Lake in nearby Glacier National Park. On the date the Logging Lake sample was collected, pH measured 7.78 and specific conductance measured 43. This species was also reported (as N. kozlowi var. elliptica) from a small pond in the Brooks Range of Alaska (Foged 1981).

Lake  Levale 1 1
Credit: Loren Bahls
Lake Levale, Bob Marshall Wilderness, Montana: home of Neidium bobmarshallensis.

Original Description

Valves lanceolate with broadly rounded, very weakly protracted apices. Valve length 60–79 μm; valve width 14.8–17.8 μm. A longitudinal line evident along each margin. Axial area straight and narrow, flaring a bit near the central area. Central area wide, rectangular, oriented diagonally to the apical axis. Central area bordered by short faint striae along valve margins. Raphe lateral, becoming filiform at the proximal ends, which are hooked sharply in opposite directions. Striae oriented diagonally across the valve face, 13–15 in 10 μm. Areolae 20–24 in 10 μm.

  • Author
    Bahls 2013
  • Length Range
    60-79 µm
  • Width
    14.8-17.8 µm
  • Striae in 10µm

Original Images

Neidiumbobmarshall Origimag001
Neidiumbobmarshall Origdesc002

Cite This Page

Bahls, L. (2013). Neidium bobmarshallensis. In Diatoms of North America. Retrieved June 21, 2024, from https://diatoms.org/species/neidium_bobmarshallensis


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