Phenotypic and genotypic validation of the rare species Sphaerospermopsis eucompacta comb. nov. (Nostocales, Cyanobacteria) isolated from China

The heterocystous cyanobacterium Anabaena eucompacta R. Li & M. Watanabe was found in China, and two unialgal strains were isolated. The species was characterized by its twisted and tight spirals and the relative position of spherical akinetes to heterocysts (adjacent to one or both sides of heterocysts). However, the taxonomic and phylogenetic position of the species remained to be characterized because of the lack of molecular data. In this study, we used a polyphasic approach, based on both morphological and molecular characters (sequences of 16S rRNA and 16S-23S rRNA), to evaluate its taxonomic position. Our results showed that A. eucompacta was a distinct species and that it should be transferred to the recently established genus Sphaerospermopsis as S. eucompacta (R. Li & M. Watanabe) X. Li & R. Li comb. nov.