New Taxa of Filamentous Cyanobacteria from Freshwater Habitats in China: Description of Neoleptolyngbya gen. nov. with Two Species, and Pseudoleptolyngbya wuhanensis sp. nov

TL;DR

This paper describes two new species in a new genus and one new species of Pseudoleptolyngbya from Chinese freshwater habitats, using genetic and structural analyses.

Contribution

The discovery of Neoleptolyngbya gen. nov. and Pseudoleptolyngbya wuhanensis sp. nov., expanding cyanobacterial diversity in China.

Findings

Two new species in a novel genus (Neoleptolyngbya) and one new Pseudoleptolyngbya species were identified.

16S rRNA gene sequences showed similarity below the cyanobacterial species/genus delineation threshold.

16S–23S ITS secondary structures revealed species-specific differences supporting taxonomic novelty.

Abstract

Three cyanobacterial strains (CB-4, GQSK-2, and LHH-2) with thin, simple filaments were isolated from freshwater habitats in China. In this study, a polyphasic approach, integrating 16S rRNA gene phylogenetic analyses, p-distance calculation, 16S-23S ITS secondary structures, and morphological and ecological observations, was employed to resolve the taxonomic status of these strains. The results confirmed the existence of two new species within a novel genus (Neoleptolyngbya) and one additional new species of Pseudoleptolyngbya (Leptolyngbyaceae): Neoleptolyngbya gaoqiuensis sp. nov. (strain GQSK-2), Neoleptolyngbya chanbaensis sp. nov. (strain CB-4), and Pseudoleptolyngbya wuhanensis sp. nov. (strain LHH-2). In the 16S rRNA phylogeny, strains GQSK-2 and CB-4 formed a well-supported, independent lineage sister to the Leptolyngbyopsis clade, while strain LHH-2 clustered with two recognized Pseudoleptolyngbya species in a distinct clade. Sequence similarity analyses revealed that the 16S rRNA gene sequences of GQSK-2 and CB-4 shared a maximum similarity of 94.2% with those of phylogenetically related established genera, and the 16S rRNA gene sequence of LHH-2 exhibited a maximum similarity of 95.7% with its closest Pseudoleptolyngbya relatives, both values below the threshold for cyanobacterial species/genus delineation. Furthermore, comparative analysis of the 16S–23S ITS secondary structures between the three strains and their respective reference strains revealed significant species-specific differences, providing additional evidence for their taxonomic novelty. The discovery of these novel taxa enriches the cyanobacterial diversity in China and lays a theoretical foundation for the conservation and sustainable utilization of algae resources.

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