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Aulacoseira

Aulacoseira forms long tube-like series of cylindrical cells which connect via spines.  The length and shape of these spines, as well as the patterns of its areolae, are useful for identifying between species.  It is a common genus of centric diatoms in many freshwater environments. 

A. ambigua

  • Cells are 3-15 µm in diameter, 5-15 µm in height, and have a height : width ratio >1.

  • 17-22 rows of areolae in 10 µm.  

  • Rows curve to the right towards the spines.

  • Spines are short, pointed, and emerge from between each row of areolae.

For more information, visit diatoms.org here.

A. granulata

  • Cells are 4-17 µm in diameter, 4-20 µm in height, and have a height : width ratio of >0.8, up to 5.

  • 8-18 rows of areolae in 10 µm. 

  • Rows curve slightly to the right towards the spines.

  • Easily identified by one or a few long spines, extending nearly the length of the cell. 

For more information, visit diatoms.org here.

All images taken and owned by Thomas Shannon, in association with the University of Wisconsin - Madison and the UW-Madison Center for Limnology.

For information on image use, please contact tshannon3@wisc.edu

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