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Algae 1997;12(4): 235-246. |
Taxonomy and Phylogeny of Scenedesmus
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Ebrhard H. Hegewald
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Research Center Julich
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ABSTRACT |
The first taxa of the genus Scenedesmus were described in 1828 and studied for more than one hundred years only by light microscopy. The position, delimitation and subdivision of the genus has often been changed. The study of the cell wall structures in the transmission electron microscopy and finally DNA studies (G/C content, homologies, reassociation, sequence analyses) have been very important for progress in the taxonomy of the genus. The combined studies of light and electron microscopy and of DNA studies resulted in a better understanding of the relationship of taxa. Besides overinterpreted variability, polymorphism occurs with the switching of qualitatively different cell wall ultrastructures with the following generation. According to recent publications the genus is now divided into only two subgenera. Several taxa from the former family Chlorellaceae (now classes Trebouxiophyceae) were transferred to Scenedesmus and the genera Tetradesmus and Enallax should become retransferred to scenedesmus.
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Key words:
Chlorella, Dicloster, DNA, electron microscopy, morphology, phylogeny, physiology, Scenedesmus, taxonomy, Tetradesmus |
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