Amazonocrinis thailandica sp. nov. (Nostocales, Cyanobacteria), a novel species of the previously monotypic Amazonocrinis genus from Thailand

Abstract

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.

Insights into the phylogenetic inconsistencies of the genus Amazonocrinis and description of epilithic Amazonocrinis malviyae sp. nov. (Cyanobacteria, Nostocales) from Jammu and Kashmir, India

“…The phylogenetic clustering observed in this study is not in congruence with the 16S rRNA gene trees represented in Alvarenga et al [17] and Tawong et al [33]. This is a matter of concern as in the 16S rRNA gene phylogenetic trees represented by Alvarenga et al [17] and Tawong et al [33], A. nigriterrae CENA67 T , A.…”

“…NIES-4103 (AP018288), Aliinostoc sp. SA22 (MK956204) and A. nigriterrae CENA66 (MW327025) and the recently described Amazonocrinis thailandica NUACC02 T /NUACC03 (LC657918/LC657919) [33] clustered within the Amazonocrinis clade II (Fig. 3).…”

“…SA22 (MK956204) and A. nigriterrae CENA66 (MW327025) and the recently described Amazonocrinis thailandica NUACC02 T /NUACC03 (LC657918/LC657919) [33] clustered within the Amazonocrinis clade II (). Further, the 16S rRNA gene percentage similarity between the members of clades I and II was in the range of 95.0–97.9 % ().…”

“…While it is understandable that taxonomic interpretations, based especially on phylogenetic evidence may be subject to change with the addition of more taxa in the future (as seen in the case of Aliinostoc and Pseudoaliinostoc ), the case of Amazonocrinis was different as the sequences that caused the split of the genus were present in the public domain even before the discovery of the new genus. Both Alvarenga et al [17] and Tawong et al [33] missed two sequences (excluding the sequence of 19C-PS T ). Coincidentally, an addition of only these missing sequences simply split the entire Amazonocrinis cluster.…”

“…It must be noted that in both the studies the sequences corresponding to Nostoc ellipsosporum V (AJ630450) and Nostoc ellipsosporum str. Lukešová 51_1991 (MG596757) were absent [17, 33], and we speculate that the addition of these sequences to the phylogenetic analysis probably led to the splitting of the Amazonocrinis clade. This issue of low taxon sampling, particularly in the Nostocales, resulted in similar taxonomic complications when the genus Minunostoc was described [39].…”