• Category
  • Length Range
    123-195 µm
  • Width Range
    26-31 µm
  • Striae in 10 µm
    longitudinal striae 19-22, transverse striae 24-25



Valves area lanceolate to weakly rhombic, with rounded apices. Longitudinal ribs are straight, except at the central nodule, where they are constricted. The distal end of the longitudinal ribs is spatulate and blunt. The raphe is straight and filiform. Both the proximal and distal raphe ends are T-shaped. Transverse striae are parallel, except at the apices where they are circumradiate. Longitudinal striae are wavy throughout.


Frustulia bahlsii has been reported from Maine, New Hampshire, New Jersey, and North Carolina (Edlund and Brant 1997). The type locality, Flat Laurel Gap Bog, Haywood County, North Carolina, is a sphagnum bog with low pH and low conductivity. We have also observed F. bahlsii in the Upper Peninsula of Michigan and southern Alaska.

Original Description

Cells solitary. Valves lanceolate to rhombic-lanceolate, valve face flat, apices rounded to slightly rostrate (Figs 1-6). Valve length 98-193 µm, valve breadth 24-33 µm. Central area not differentiated from narrow axil area on valve exterior (Figs 5, 7). Axial area terminates in a slightly expanded spatulate hyaline field (Figs 1-4, 9). Striae punctate; longitudinal striae parallel to slightly undulate, 16-23 in 10 µm and transverse striae parallel to slightly undulate, 20-26 in 10 µm (Figs 1-4, 11-14). Striae continuous around valve apices (Figs 9, 10). Areolae poroid, occluded internally by domed vela (Figs 7-10). Raphe straight and simple; its proximal and distal ends T-shaped on the valve exterior (Figs 7, 9). Raphe enclosed between two internally thickened siliceous ribs (Figs 6, 8, 10). Ribs parallel to slightly curved internally along axial area, slightly expanded around proximal raphe ends to form spatulate thickening rather than a "porte-crayon" usually present in the genus (Fig. 10).

  • Author
    Edlund and Brant 1997
  • Length Range
    98-193 µm
  • Width
    24-33 µm
  • Striae in 10µm
    longitudinal striae 16-23, transverse striae 20-26

Original Images

Frustulia bahlsii orig illus
Frustulia bahlsii orig illus 2
Frustulia bahlsii orig illus 3
Frbahls Original Descript

Citations & Links

Cite This Page

Burge, D, and Edlund, M, and Brant, L. (2015). Frustulia bahlsii. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/frustulia_bahlsii


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