Staurosirella leptostauron var. dubia

(Grunow) Edlund 1994      Category: Araphid
BASIONYM: Fragilaria harrisonii var. dubia Grunow 1862
SYNONYM(S): Fragilaria leptostauron var. dubia (Grunow) Hust. 

Staurosirella leptostauron


Staurosirella martyi

LM scalebar = 10 µm = 80 pixels.


Contributor: Eduardo A. Morales - October 2010
Length Range: 4-38 µm
Width Range: 3.5-6.5 µm
Striae in 10 µm: 6-10


Valves are heavily silicified, lanceolate in larger specimens and elliptical in smaller specimens, 3.5-6.5 µm wide by 4-38 µm long. Valves demonstrate rostrate ends in larger specimens becoming rounded in smaller valves. Valve face flat, or slightly undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular and form ribbon-like colonies, probably joined by linking spines. The colonies are attached to the substratum at one end by a frustule attached by a mucilage pad, or colonies may be planktonic. The axial area is lanceolate. The striae are distinct, composed of lineolae gradually decreasing in size from the valve face/mantle edge to both the central sternum and the valve mantle, 6-10 in 10 µm. The lineolae bear finely branched volae. Lineolae are long forming wide striae that have the appearance of punch holes on the valve. Striae vary from parallel in the central area to radiate toward the valve ends. Striae extend deeply into the valve mantle. Costae are wider than the striae. The spines are reduced to solid prominences, two on each costa, between the striae. Striae are present along the valve face edge, except at the apices. Well-developed, ocellulimbus type, apical pore fields with round poroids are present. Apical pore fields are located on the valve mantle. Rimoportula are absent. Scab-like structures, or blisters, are absent. Copulae, or girdle bands are open and do not bear perforations. Valvocopula are wider than other girdle elements and bear developed fimbriae (finger-like projections).

Original Description

Basionym: Fragilaria harrisonii var. dubia
Author: Grunow 1862
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Morales, E. (2010). Staurosirella leptostauron. In Diatoms of the United States. Retrieved April 26, 2018, from

Species: Staurosirella leptostauron

Contributor: Eduardo A. Morales

Reviewer: Sarah Spaulding


Edlund, M.B. (1994). Additions and confirmations to the algal flora of Itasca State Park. II. Diatoms from Chambers Creek. Journal of the Minnesota Academy of Science 59(1):10-21.

Grunow, A. (1862). Die österreichischen Diatomaceen nebst Anschluss einiger neuen Arten von andern Lokalitäten und einer kritischen Uebersicht der bisher bekannten Gattungen und Arten. Erste Folge. Epithemieae, Meridioneae, Diatomeae, Entopyleae, Surirelleae, Amphipleureae. Zweite Folge. Familie Nitzschieae. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 12: 368, Pl. 7, fig. 8.

Williams, D.M. and Round, F.E. (1987). Revision of the genus Synedra Ehrenb. Diatom Research 1(2): 313-339.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Staurosirella leptostauron var. dubia CAS

North American Diatom Ecological Database (NADED)

NADED ID: 175007

Autecology Discussion

Frustules attach to substrates by mucilage pads; ribbon-like colonies are common.

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

Staurosirella leptostauron var. dubia

EMAP Response Plots

Staurosirella leptostauron var. dubia

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.