• Category
  • Length Range
    6-38 µm
  • Width Range
    4.5-5.0 µm
  • Striae in 10 µm
  • Reported As
    Pseudostaurosira subsalina (Morales 2005, pg. 115, Figs. 1–20, 80-85)



Valves linear to elliptic, with cuneate to rounded ends. The central area is linear to lanceolate. The valve face connects sharply with the mantle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular. Cells often form short ribbon-like colonies, joined by linking spines. The axial area is narrow and linear or, less frequently, slightly lanceolate. Striae are distinctly punctate and composed of square to round areolae, decreasing in size from valve face/mantle junction to axial area. Striae are slightly alternate (referring to how striae from opposite margins "meet" at the central sternum). Areolae bear branched volae. Areolae on the valve mantle may bear flaps partially occluding the external areolar opening. The striae are interrupted at the valve face/mantle junction by spines. Costae are broader than the striae. Spines are flat, spatulate and solid. Spines are present along the valve face edge, except at the apices. Conspicuous scar-like depositions are present along abvalvar edge of valve mantle. Reduced apical pore fields with round poroids ocellulimbus type) are present at both valve ends. Pore fields are located at the junction between the valve face and mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and do not bear perforations. Valvocopulae are wider than other girdle elements.


Pseudostaruosira americana has been reported from circumneutral water (pH 7.5), with low to medium concentrations of orthophosphate (0.24 mgl/l) and total nitrogen (0.490 mg/l) and moderate specific conductance (238 µS/cm) (Morales 2005).

Original Description

DESCRIPTION: Frustula aspectu cingulari rectangularia in catenis. Valvae isopolares lanceolatae apicibus cuneatis, 6–22 mm longae, 4.5–5.0 mm latae. Striae 16–18 in 10 mm, uniseriatae alternae parallelae. Duae ad quinque areolae in quoque stria. Sternum angustum lineare. Volae projecturis ramosis ex areolarum parietis. Spinae spatulatae. Area porellarum ad apices cum duabus seriebus poris. Rimoportulae nullae.

  • Basionym
    Fragilaria americana
  • Author
    E.Morales 2005
  • Length Range
    6-22 µm
  • Width
    4.5-5.0 µm
  • Striae in 10µm

Original Images

P Americana Orig Illus2
P Americana Description

Cite This Page

Morales, E, and Rosen, B, and Spaulding, S. (2013). Pseudostaurosira americana. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/pseudostaurosira_americana


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