# 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.

## Key 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.