A PROPOSAL FOR A NEW RED ALGAL ORDER, THE THOREALES

The freshwater red algal genera Nemalionopsis and Thorea are currently classified in the family Thoreaceae of the Batrachospermales. However, these two genera differ from other members of the order in having multiaxial thalli. The phylogenetic relationships of the genera were investigated using a co...

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Bibliographic Details
Published in:Journal of phycology 2000-12, Vol.36 (s3), p.62-62
Main Authors: Sheath, R. G., Müller, K. M., Sherwood, A.R.
Format: Article
Language:English
Subjects:
Nemalionopsis
Thorea
Thoreales
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Summary:The freshwater red algal genera Nemalionopsis and Thorea are currently classified in the family Thoreaceae of the Batrachospermales. However, these two genera differ from other members of the order in having multiaxial thalli. The phylogenetic relationships of the genera were investigated using a combination of DNA sequence analysis (rbcL and 18S rRNA genes) and transmission electron microscopy. In both gene trees, Nemalionopsis and Thorea form well supported clades (87–100% bootstrap values) separate from other members of the Batrachospermales as well as taxa from the Acrochaetiales, Palmariales, and Nemaliales. In addition, analysis of the secondary structure of the 18S rRNA gene in Nemalionopsis and Thorea reveals an additional helix, which is not present in any of the other taxa within the Rhodophyta. Pit plugs of the Thoreaceae also differ from those of other members of the Batrachospermales in not having an outer cap layer that is not universally domed. Based on these findings, it is proposed that Nemalionopsis and Thorea represent a distinct taxonomic group that should be recognized as a new order, the Thoreales.
ISSN:0022-3646
1529-8817
DOI:10.1046/j.1529-8817.1999.00001-185.x