Aulacoseira
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| Thwaites |
Aulacoseira is a genus of diatoms (Bacillariophyta) with around 18 species that occur exclusively in freshwater.
features
Aulacoseira is a centric diatom. It forms unbranched threads made of long cylindrical cells that have a thorn-like suspension at the end of the cell. The individual cells have the typical diatom shell consisting of two counters. This is rectangular in the side view and circular in the shell view. The shell surface has a clearly granular structure. The cell nucleus sits in the middle. At the edge there are several disc-shaped plastids that are colored golden brown by fucoxanthin . The cells are 3 to 30 micrometers in diameter.
Asexual reproduction occurs through the typical division of diatoms into two parts, which leads to the reduction of the cells. The cell threads break easily. Sexual reproduction occurs through the oogamy characteristic of centric diatoms . This is followed by cell enlargement in the course of auxospore formation. The formation of permanent cells directly from vegetative cells is also known.
Occurrence
Aulacoseira occurs in the sediment, but also in the plankton of stagnant, eutrophic waters. It can also be found in brackish water.
supporting documents
- Karl-Heinz Linne von Berg, Michael Melkonian u. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 , p. 238.