Pseudostaurosira elliptica

(Schumann) Edlund, Morales and Spaulding 2006      Category: Araphid
BASIONYM: Fragilaria elliptica Schumann 1867
SYNONYM(S): Staurosira elliptica (Schumann) Williams and Round 

Pseudostaurosira brevistriata


Pseudostaurosira neoelliptica

LM scalebar = 10 µm = 80 pixels.


Contributor: Eduardo Morales - October 2011
Length Range: 6-14 µm
Width Range: 3-3.5 µm
Striae in 10 µm: 14-16



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

Basionym: Fragilaria elliptica
Author: Schumann 1867
Length Range: µm
Striae in 10 µm:

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.

Original Images

Cite This Page:
Morales, E. (2011). Pseudostaurosira elliptica. In Diatoms of the United States. Retrieved October 26, 2016, from

Species: Pseudostaurosira elliptica

Contributor: Eduardo Morales

Reviewer: Rex Lowe


Edlund, M.B., Morales, E.A. and Spaulding, S.A. (2006). The type and taxonomy of Fragilaria elliptica Schumann, a widely misconstrued taxon. In: Witkowski, A. (Ed.). Proceedings of the 18th International Diatom Symposium. Miedzyzdroje, Poland. pp 53-59. Biopress Limited, Bristol, England.

Schumann, J. (1867). Preussiche Diatomeen. Schriften der Physikalisch-Ökonomischen Gesellschaft zu Könisberg 8: 37-68.

Williams, D.M. and Round, F.E. (1987). Revision of the genus Fragilaria. Diatom Research 2: 267-288.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Pseudostaurosira elliptica CAS

North American Diatom Ecological Database (NADED)

NADED ID: 73025

Autecology Discussion

EMAP Assessment

The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Pseudostaurosira elliptica

EMAP Response Plots

Pseudostaurosira elliptica

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.