• Category
  • Length Range
    6-14 µm
  • Width Range
    3-3.5 µm
  • Striae in 10 µm
  • Synonyms
    Staurosira elliptica (Schum.) D.M.Williams and Round




Valves elliptic to lanceolate. Valves with cuneate to rounded ends. The central area is broad and lanceolate. The valve face connects gradually with the mantle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view frustules are rectangular. Cells form ribbon-like colonies, joined by linking spines. Striae are distinct and composed of one, rarely two or more, areolae on the valve face and mantle. 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 hollow. Spines are present along the valve face edge, except at the apices. Reduced, ocellulimbus type, apical pore fields with round poroids are present at both valve ends. Pore fields are located at the junction between valve face/mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and do not bear perforations. Valvocopulae are wider than other girdle elements.

This taxon is difficult to recognize under the light microscope and a clear separation from Pseudostaurosira brevistriata may not be possible with small specimens. Here, the Schumann type material studied in detail by Edlund et al. (2006) is presented.


Original Description

Fragilaria elliptica. Fr. minima, elliptica, striis granulatis interruptis, taenia longitudinali plus minusive aperta. long 2-4, lat.= 4-5/10 longitudinis, striae 25 in 1/100 L.

  • Basionym
    Fragilaria elliptica
  • Author
    Schum. 1867

Original Images

Iconotype 1
Original Description 1

EMAP Assessment

EMAP Distribution

Staurosira Elliptica   Schumann   Williams Et  Round 3
Map 3

Response Plots

Staurosira Elliptica   Schumann   Williams Et  Round

Cite This Page

Morales, E. (2011). Pseudostaurosira elliptica. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/pseudostaurosira_elliptica


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