Mastigocladus laminosus (Stigonematales, Cyanobacteria): phylogenetic relationship of strains from thermal springs to soil-inhabiting genera of the order and taxonomic implications for the genus

Abstract

J. Kaštovský and J.R. Johansen. 2008. Mastigocladus laminosus (Stigonematales, Cyanobacteria): phylogenetic relationship of strains from thermal springs to soil-inhabiting genera of the order and taxonomic implications for the genus. Phycologia 47: 307–320. DOI: 10.2216/07-69.1

The morphology, ecology, life cycles, ultrastructure and sequences of the 16S rRNA gene of four cyanobacteria strains from different localities putatively identified as Mastigocladus laminosus were studied. Our strains fall into three separate clades, and conclusions based on “classical” taxonomical methods correspond with conclusions based on sequences of the 16S rRNA gene. According to all methods used, M. laminosus sensu stricto includes true branching strains from thermal springs only, and the genus Mastigocladus is separated from all soil species in the genus Fischerella. The genera Mastigocladus and Fischerella have a confused taxonomic history because the generitype of both taxa was collected from Karlovy Vary Hot Spring within 15 years of the description of each. Strains with other ecological (nonthermal locality) or morphological characteristics (thermal habitat but unbranched forms) belong to different genera. We begin the revision process by moving Mastigocladus laminosus var. indica to Fischerella indica stat. nov., comb. nov. Full resolution of the taxonomic confusion surrounding Mastigocladus and Fischerella will likely require a proposal for designation of a new type species for the genus Fischerella.

Key Words::

• Cyanobacteria
• Fischerella
• Mastigocladus
• Phylogeny
• Stigonematales
• Thermal springs
• 16S rRNA

ACKNOWLEDGMENTS

We thank Prof. Jiří Komárek for helpful discussions and inspiration and Dr. L. Kováčik, Prof. B.V. Gromov and Prof. G.U. Schlosser for providing strains. Dr. Paul Silva provided an extensive review of pre–starting date nomenclatural history of Mastigocladus laminosus. This study was supported by the Mattoni award, MSM 6007665801 and GAČR206/08/0318. Sequencing was supported by National Science Foundation award DEB 0206360. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.