Nodosilinea hunanesis sp. nov. (Prochlorotrichaceae, Synechococcales) from a Freshwater Pond in China Based on a Polyphasic Approach

Abstract

A cyanobacterial strain (ZJJ01), morphologically identified as a Leptolyngbya-like species was isolated from a freshwater pond in Zhangjiajie National Forest Park, China, and it was characterized through a polyphasic study based on morphological, ecological, and molecular data. Morphologically, the strain fits the description of Leptolyngbya well, but under further examination, it formed a distinctive structure, namely nodules, which confirmed that it belonged to the genus of Nodosilinea. The 16S rRNA gene threshold value and 16S rRNA phylogenetic analyses clearly confirmed that the studied strain belongs to the genus Nodosilinea but that it is phylogenetically distinct from the 10 other species of Nodosilinea. Furthermore, The D1–D1’ and Box–B helix of the 16S–23S ITS region of the strain ZJJ01 were also different from those of previously described Nodosilinea species. On the basis of this polyphasic approach, here, we provide a description of the new taxon: Nodosilinea hunanesis sp. nov.

Unbiased analyses of ITS folding motifs in a taxonomically confusing lineage: Anagnostidinema visiae sp. nov. (cyanobacteria)

“…Likewise, ITS rDNA region dissimilarity shows that A. visiae is between 3.9% and 6.3% dissimilar from the other identified taxa in the genus. Interestingly, this work re‐emphasizes a potentially confounding note when constructing phylogenies using only the 16S rDNA gene (Cai et al, 2022; Osorio‐Santos et al, 2014). Our strains, and indeed all strains in the genus for which we had sequence data, shared remarkedly high 16S rDNA gene similarity (99.9%–100%, Table 2).…”

“…To create more discrimination for novel taxa, researchers have turned to the folding motifs in the 16S–23S ITS rDNA region, in particular the D1–D1′, V3, and Box B structures (Boyer et al, 2002; Cai et al, 2020; Iteman et al, 2000). Numerous new taxa have been proposed due to apomorphies or discontinuities in these regions and, in some cases, concurrent transfer of previously described species (e.g., Nodosilinea hunanensis sensu, Cai et al, 2022; Oculatella coburnii sensu Osorio‐Santos et al, 2014; Koksharova & Wolk, 2002). Although an admirable endeavor, questions arise: How variable are these structures themselves?…”

Revealing the Diversity of Thin Filamentous Cyanobacteria, with the Discovery of a Novel Species, Pegethrix qiandaoensis sp. nov. (Oculatellaceae, Oculatellales), in a Freshwater Lake in China

“…To establish the cyanobacterial taxonomic system consisting of monophyletic groups at all ranks is becoming an ideal aim for studying the true diversity of cyanobacteria [33,34]. Further, with the usage of the polyphasic approach, a large number of cyanobacterial new genera and species has been described, which subsequently led to substantial taxonomic revisions, especially at the order and family levels [4,14,16].…”

Stenomitos nagquensis sp. nov. (Leptolyngbyaceae, Cyanobacteria) from a Meadow Wetland in the Tibet Plateau: A Novel Species Studied Based on a Polyphasic Approach

“…In this circumstance, the p-distance method based on the 16S rRNA gene cannot be used as the only absolute basis for separating terminal taxonomic levels (i.e., genera and species). Therefore, apart from utilizing the gold standard 16S-rRNA-gene-based phylogeny, other informative molecular characteristics-including the analysis of the p-distance dissimilarity of 16S-23S ITS and the prediction of secondary structures-have proven their usefulness as strong additional sources of evidence to support the high similarity values given by the 16S rRNA gene sequence comparison across cyanobacterial lineages [55][56][57].…”

“…The common problems include either a lack of unique features for diagnosis, the possession of overlapping features with different or unrelated groups [11,55], or both. For example, a cyanobacterial strain (ZJJ01) from a freshwater pond isolated from Zhangjiajie National Forest Park, China, appeared to be morphologically similar to Leptolyngbya but was found to belong to the genus Nodosilinea after further morphologic examination and confirmation from molecular data [57]. Members of the genus Stenomitos are not exempt from morphological plasticity, and they exhibit morphological variability as well.…”