Brachysira brebissonii

R.Ross in B.Hartley 1986      Category: Symmetrical biraphid
BASIONYM: Navicula aponica var. brachysira Bréb. ex. Kütz. 1849
SYNONYM(S): Anomoeoneis serians var. brachysira (Bréb. ex. Kützing) Hustedt  

Brachysira arctoborealis


Brachysira hannae

LM scalebar = 10 µm = 80 pixels.


Contributor: Paul Hamilton - December 2010
Length Range: 11-36 µm
Width Range: 4-8 µm
Striae in 10 µm: 26-35


Valves are small, rhombic-lanceolate to elliptical-lanceolate with narrow rounded apices. Striae are weakly radiate from center to apex. The axial area is narrow and straight. The raphe is positioned within two ribs that lie on the external face of the valve. The ribs terminate at the edge of the central area and the apices. The raphe is filiform and straight, with expanded drop-like proximal fissures and T-shaped distal fissures. Areolae are typically elongate. The striae are interrupted by hyaline areas, creating a “wave-like” appearance of the striae. Central area is small, circular to slightly oval. Small papillae (silica nodules) are often scattered across the external valve face, visible in SEM. A thickened rib is present along the valve margin and apex, separating the valve face from the mantle. Striae on the mantle are uniseriate and aligned with striae on the valve face. In SEM, the internal proximal raphe fissures are unilaterally deflected. The distal fissures are bounded by small helictoglossa. Areolae are covered internally with flat hymenes.

Original Description

Basionym: Navicula aponica var. brachysira
Author: Bréb. ex. Kütz. 1849
Length Range: µm
Striae in 10 µm:

Original Description

  1. N: brachysira Bréb. (T. V. F. 11. c. d. e.) unterscheidet sich von der N. aponica nicht wesentlich, sie bleibt nach der Theilung nur länger als die typische Form verbunden und erscheint dann eine Zeit lang in Kurzen Bändern, wie das auch öfters bei der N. serians der Fall ist. De Brébisson hat sie bei Falaise beobachet.

Original Images

Cite This Page:
Hamilton, P. (2010). Brachysira brebissonii. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Brachysira brebissonii

Contributor: Paul Hamilton

Reviewer: Sarah Spaulding


Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 pp.

Gaiser, E.E. and Johansen, J. (2000). Freshwater diatoms from Carolina bays and other isolated wetlands on the Atlantic Coastal Plain of South Carolina, USA, with descriptions of seven taxa new to science. Diatom Research 15(1): 75-130. 10.1080/0269249X.2000.9705487

Hartley, B. (1986). A check-list of the freshwater, brackish and marine diatoms of the British Isles and adjoining coastal waters. Journal of the Marine Biological Association of the United Kingdom 66: 531-610.

Lange-Bertalot, H. and Moser, G. (1994). Brachysira Monographie der Gattung. Bibliotheca Diatomologica 29: 1-212.

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Shayler, H.A. and Siver, P.A. (2004). Biodiversity of the genus Brachysira in the Ocala National Forest, Florida, U.S.A. Proceedings of the Seventeenth International Diatom. Symposium Ottawa, Canada, 25th – 31st August 2002 (M. Poulin, ed.), Biopress limited, Bristol. p. 309-333.

Siver, P.A. and Hamilton, P.B. (2011). Diatoms of North America: The Freshwater Flora of Waterbodies on the Atlantic Coastal Plain. Iconographia Diatomologica 22.

Siver, P.A., Hamilton, P.B., Stachura-Suchoples, K. and Kociolek, J.P. (2005). Diatoms of North America. The Freshwater Flora of Cape Cod. Iconographia Diatomologica 14: 1-463.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Brachysira brebissonii CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Brachysira brebissonii was widely distributed across North America in acidic waterbodies. In studies along the Altantic coastal plain this taxon was observed in ponds that were moderately acidic and oligotrophic to mesotrophic. Despite being widespread, it was usually found in low numbers. pH and TP optima (average weighted means, AWM) from four studies (Siver & Hamilton, 2011; Siver et al. 2005; Camburn & Charles 2000; Gaiser & Johansen 2000) range from 4.7-5.8 and 5.7-13.2 for pH and TP (µg/L) respectively.

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

Brachysira brebissonii

EMAP Response Plots

Brachysira brebissonii

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.