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POLYPHYLETIC ORIGIN OF THE DICTYOSPHAERIUM MORPHOTYPE WITHIN CHLORELLACEAE (TREBOUXIOPHYCEAE)1
Article first published online: 19 MAR 2010
© 2010 Phycological Society of America
Journal of Phycology
Volume 46, Issue 3, pages 559–563, June 2010
How to Cite
Krienitz, L., Bock, C., Luo, W. and Pröschold, T. (2010), POLYPHYLETIC ORIGIN OF THE DICTYOSPHAERIUM MORPHOTYPE WITHIN CHLORELLACEAE (TREBOUXIOPHYCEAE). Journal of Phycology, 46: 559–563. doi: 10.1111/j.1529-8817.2010.00813.x
Received 4 May 2009. Accepted 18 November 2009.
- Issue published online: 2 JUN 2010
- Article first published online: 19 MAR 2010
The green algal Dictyosphaerium morphotype is characterized by spherical or oval cells connected by gelatinized strands to microscopic colonies, which are covered by prominent mucilaginous envelopes. Combined SSU and ITS rRNA gene sequence analyses revealed that this morphotype evolved independently both in the Chlorella and Parachlorella clades of the Chlorellaceae. It was shown that strains exhibiting the morphology of the type species Dictyosphaerium ehrenbergianum Nägeli established a sister lineage to Parachlorella. The strain D. ehrenbergianum CCAP 222/1A was designated as an authentic strain for establishing the epitype of the genus Dictyosphaerium. The comparison of this strain with the authentic strain of Parachlorella beijerinckii Krienitz, E. Hegewald, Hepperle, V. Huss, T. Rohr et M. Wolf (SAG 2046) showed considerable differences in the secondary structure of the ITS region. Within the whole ITS-1 and ITS-2 region, 27 compensatory base changes (CBCs) were recognized. In the conserved Helix III of the ITS-2, five CBCs/HemiCBCs were detected. This is a conclusive argument for separation of these two species. The clear definition of Dictyosphaerium is intended to be the necessary starting point of taxonomic reevaluation of Dictyosphaerium-like algae within different evolutionary lineages of the Chlorellaceae.