Algae

Terrestrial cyanobacteria are extremely diverse. In urban areas, they can be found as black stains on the surface of building walls, stone monuments, or man-made structures. Many of the terrestrial cyanobacteria are still understudied. To expand knowledge of terrestrial cyanobacterial diversity, a polyphasic characterization was performed to identify 12 strains isolated from campus of University of the Ryukyus, Okinawa, Japan. Multigene phylogenetic analyses based on 16S rRNA gene and 16S-23S rRNA internal transcribed spacer (ITS) region showed that the isolated strains formed two independent subclades within Nodosilinea, and were distantly related to all described Nodosilinea species. The 16S-23S rRNA ITS secondary structures showed variations for D1-D1′ and Box B domain, while V3 domain was almost identical among entire species of Nodosilinea, including the studied strains. In addition, a unique morphological character, i.e. forming nodule or spiral shape, was also observed in certain studied strains. According to polyphasic characterization, Nodosilinea coculeatus sp. nov. and Nodosilinea terrestrialis sp. nov., were proposed as two new species of terrestrial cyanobacteria from Okinawa.

Progress in phylogenomic analysis has led to a considerable re-evaluation of former cyanobacterial system, with many new taxa being established at different nomenclatural levels. The family <i>Geminocystaceae</i> is among cyanobacterial taxa recently described on the basis of polyphasic approach. Within this family, there are six genera: <i>Geminocystis</i>, <i>Cyanobacterium</i>, <i>Geminobacterium</i>, <i>Annamia</i>, <i>Picocyanobacterium</i>, and <i>Microcrocis</i>. The genus <i>Geminocystis</i> previously encompassed two species: <i>G. herdmanii </i>and <i>G. papuanica</i>. Herein, a new species <i>G. urbisnovae</i> was proposed under the provision of the International Code of Nomenclature for algae, fungi, and plants (ICN). Polyphasic analysis was performed for five strains from the CALU culture collection (St. Petersburg State University, Russian Federation), and they were assigned to the genus Geminocystis in accordance with high 16S rRNA gene similarity to existing species, as well as because of proximity to these species on the phylogenetic trees reconstructed with RaxML and Bayes methods. Plausibility of their assignment to a separate species of the genus <i>Geminocystis</i> was substantiated with smaller cell size; stenohaline freshwater ecotype; capability to complementary chromatic adaptation of second type (CA2); distinct 16S rRNA gene clustering; sequences and folding of D1−D1′ and B box domains of the 16S−23S internal transcribed spacer region. The second objective pursued by this communication was to provide a survey of the family <i>Geminocystaceae</i>. The overall assessment was that, despite attention of many researchers, this cyanobacterial family has been understudied and, especially in the case of the crucially important genus Cyanobacterium, taxonomically problematic.

Cyanobacteria are distributed worldwide, and many new cyanobacterial species are discovered in tropical region. TheNostoc-like genus Amazonocrinis has been separated from the genus Nostoc based on polyphasic methods. However,species diversity within this genus remains poorly understood systematically because only one species (Amazonocrinisnigriterrae) has been described. In this study, two novel strains (NUACC02 and NUACC03) were isolated from moist ricefield soil in Thailand. These two strains were characterized using a polyphasic approach, based on morphology, 16S rRNAphylogenetic analysis, internal transcribed spacer secondary structure and ecology. Phylogenetic analyses based on 16SrRNA gene sequences confirmed that the two novel strains formed a monophyletic clade related to the genus Amazonocrinisand were distant from the type species A. nigriterrae. The 16S rRNA gene sequence similarity (<98.1%) betweennovel strains and all other closely related taxa including the Amazonocrinis members exceeded the cutoff for speciesdelimitation in bacteriology, reinforcing the presence of a new Amazonocrinis species. Furthermore, the novel strainspossessed unique phenotypic characteristics such as the presence of the sheath, necridia-like cells, larger cell dimensionand akinete cell arrangement in long-chains and the singularity of D1–D1′, Box-B, V2, and V3 secondary structures thatdistinguished them from other Amazonocrinis members. Considering all the results, we described our two strains as Amazonocrinisthailandica sp. nov. in accordance with the International Code of Nomenclature for Algae, Fungi and Plants.