• ALGAE
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• v.35 no.1
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• pp.1-15
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• 2020

Two strains isolated from a subtropical region in China, were morphologically identified as a Nostoc-like species, but its taxonomic identity was unknown. In this study, these two strains were taxonomically and phylogenetically characterized based on polyphasic approach combining morphological and genetic characteristics. Though both were virtually indistinguishable from Nostoc in field and cultured material, these two strains were phylogenetically distinct from Nostoc based on 16S rRNA phylogeny. The 16S-23S internal transcribed spacer rRNA secondary structure of these strains showed the unique pattern of D1-D1', Box-B, and V3 helix, which distinguished them from other Nostoc-like heterocytous genera. A unique cluster separated from Nostoc sensu stricto supports the establishment of Violetonostoc gen. nov. with the type species as Violetonostoc minutum sp. nov.