Brachysira
Kützing 1836 Category: Symmetrical biraphid
TYPE SPECIES: Brachysira aponina Kützing
Image Credit: Megan Otu, Sarah Spaulding
CLASS: Bacillariophyceae
ORDER: Naviculales
FAMILY: Brachysiraceae
- Valves linear to linear-lanceolate to cruciform
- Valve apices rounded to protracted
- Striae finely punctate, form longitudinal undulations
Valves of Brachysira are linear to linear-lanceolate in outline. The ends of the valves, or apices, may be rounded to protracted. In general, the valves are symmetrical to the apical axis. Some specimens may have a slight, to strong, asymmetry to the transapical axis. The striae are finely punctate, and form longitudinal undulations. The raphe is straight and the axial area is narrow. In the SEM, an elevated siliceous ridge separating the valve face and mantle on the external valve surface is visible. Cells possess a single plastid.
Brachysira may grow singly and unattached, or it may grow at the ends of mucilaginous stalks. Species within the genus are broadly distributed across North America in a range of trophic states, with individual species characteristic of oligotrophic to dystrophic waters. Cell abundance may be especially high in low conductivity and low pH waters, for example, in bog habitats. The genus is primarily benthic, but may also be found in lake plankton, where cells may become entrained.
Cite This Page:
Spaulding, S., and Edlund, M. (2009). Brachysira. In Diatoms of the United States. Retrieved June 20, 2013, from http://westerndiatoms.colorado.edu/taxa/genus/Brachysira
Contributor: Sarah Spaulding | Mark Edlund - January 2009
Citations
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.
Compère, P. (1988). Brachysira microcephala (Grunow) Compere nom correct de “Navicula exilis” Grunow 1860 non Kutzing 1844. Mem. Soc. Roy. Bot. Belg. 10: 9-11.
Lange-Bertalot, H. and Moser, G. (1994). Brachysira Monographie der Gattung. Bibliotheca Diatomologica 29: 1-212.
Reimer, C.W. (1961). New and variable tax of the diatom genera Anomoneis Pfitz. and Stauroneis Her. (Bacillariophyta) from the United States. Proc. Acad. Nat. Sci. Philadelphia 113: 187-214.
Round, F.E. and Mann, D.G. (1981). The diatom genus Brachysira. I. Typification and separation from Anomoeneis. Archiv Protistenkunde 124: 221-231.
Shayler, H.A. and Siver, P.A. (2004). Description of a new species of the diatom genus Brachysira (Bacillariophyta), Brachysira gravida sp. nov. from the Ocala National Forest, Florida, U.S.A. Nova Hedwigia 78: 399-409.
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.
Wolfe, A.P. and Kling, H.J. (2001). A consideration of some North American soft-water Brachysira taxa and description of B. arctoborealis sp. nov. Lange-Bertalot-Festschrift Studies on Diatoms, Dedicated to Dr. Dr. h.c. Horst Lange-Bertalot on the occasion of his 65th birthday.
Wolfe, A.P., Cooke, C.A. and Hobbs, W.O. (2006). Are current rates of atmospheric nitrogen deposition influencing lakes in the eastern Canadian Arctic?. Arctic, Antarctic, and Alpine Research 38: 465-476.