taxonID	type	description	language	source
03C83513FF9B887CFF01FED9FEA4FDDE.taxon	description	Description: The strain was observed to exhibit filamentous characteristics under an optical microscope. The filaments appeared long, straight, or slightly curved, and varied in color from blue – green to dark green. Electron microscopy revealed that the ultrastructure consisted of cylindrical cells, measuring approximately 1.1 – 1.7 μm in width and 1.2 – 2.0 μm in length. The cells were generally longer than they were wide, although some were occasionally shorter than their width. The cell wall was notably thick, featuring a solid, transparent sheath with multiple filaments arranged within the thick sheath (Fig. 2). The transverse walls between the cyanobacterial cells were slightly constricted, and necrotic cells were observed. Some cell centers contained granules. The thylakoids were organized in a ring formation, with each cell containing 6 – 8 layers of thylakoids that ran parallel to the intracellular periphery. The growth pattern in BG 11 medium was a blue – green cyanobacterial mat.	en	Liu, Yang, Zhang, Yang, Wang, Xue, Geng, Ruozhen, Zhang, Bangjun (2024): Description of a novel filamentous cyanobacterial species of Leptodesmis (Leptolyngbyaceae, Cyanobacteria) in China based on the polyphasic approach. Phytotaxa 678 (2): 96-108, DOI: 10.11646/phytotaxa.678.2.1, URL: https://doi.org/10.11646/phytotaxa.678.2.1
03C83513FF9B887CFF01FED9FEA4FDDE.taxon	materials_examined	Holotype (here designated): Dry material of strain Leptodesmis xinxiangensis HNU 2023 was preserved in the Herbarium of Wenzhou University (WZUH), Wenzhou, Zhejiang Province, China, as specimen No. WZUH- ZLXX 202301. Type locality: In Xinxiang, Henan Province, China. (April 2023, 113 ° 30 ′ – 115 ° 01 ′ E, 34 ° 55 ′ – 35 ° 50 ′ N). Reference strain: The living culture was preserved in the Laboratory No. 404 of Life of Sciences, Henan Normal University, Henan Province, China. The strain number is HNU 2023.	en	Liu, Yang, Zhang, Yang, Wang, Xue, Geng, Ruozhen, Zhang, Bangjun (2024): Description of a novel filamentous cyanobacterial species of Leptodesmis (Leptolyngbyaceae, Cyanobacteria) in China based on the polyphasic approach. Phytotaxa 678 (2): 96-108, DOI: 10.11646/phytotaxa.678.2.1, URL: https://doi.org/10.11646/phytotaxa.678.2.1
03C83513FF9B887CFF01FED9FEA4FDDE.taxon	etymology	Etymology: This strain was isolated from Xinxiang city where xinxiangensis refered to and transliterated into Latin. Habitat: Adhesion grows in the freshwater area.	en	Liu, Yang, Zhang, Yang, Wang, Xue, Geng, Ruozhen, Zhang, Bangjun (2024): Description of a novel filamentous cyanobacterial species of Leptodesmis (Leptolyngbyaceae, Cyanobacteria) in China based on the polyphasic approach. Phytotaxa 678 (2): 96-108, DOI: 10.11646/phytotaxa.678.2.1, URL: https://doi.org/10.11646/phytotaxa.678.2.1
03C83513FF9B887CFF01FED9FEA4FDDE.taxon	diagnosis	Diagnosis: It differs from Leptodesmis paradoxa in its narrower cells and from L. sichuanensis and L. alaskaensis in its shorter cells. A broader range of cell lengths was observed in L. alaskaensis and L. lacustris, whereas L. xinxiangensis exhibited medium cell length. Meanwhile, L. xinxiangensis showed moderate cell width and length compared to other representatives of Leptodesmis. L. sichuanensis A 121 and L. alaskaensis are motile, whereas L. xinxiangensis, L. paradoxa and L. lacustris are immotile. Leptodesmis xinxiangensis was also distinguished based on its phylogenetic position. Molecular and Phylogenetic Analysis The target gene fragment of the filamentous cyanobacteria HNU 2023 was amplified using the above primers, and the 16 S rRNA, ITS and partial 23 S rRNA sequences with a full length of 2177 bp were obtained. The 16 S rRNA sequence of HNU 2023 was compared with that of the online alignment tool BLAST at NCBI. The similarity between Leptodesmis xinxiangensis HNU 2023 and the four species of Leptodesmis in this study was 95.67 – 96.81 % (Supplementary Table S 1), which was higher than the 95 % threshold defining bacterial genus classification and lower than the 97.5 % threshold defining bacterial species classification (Hoffmann et al., 2005). Sequences of the HNU 2023 and Cf. Leptolyngbya sp. CCNUM 2 (isolated from humid moss on forest limestone in Wuhan, China) (Zhang et al., 2019) and Cf. Leptolyngbya sp. Greenland 9 (isolated from Arctic hot springs in Greenland) (Roeselers et al., 2007) were found to have similarities of between 99.63 % and 100 % (Supplementary Table S 1), thereby indicating a high probability that the uncultured cyanobacterium and Leptodesmis xinxiangensis HNU 2023 were strains of the same species. A phylogenetic tree of the 16 S rRNA gene was constructed based on the neighbor-joining method (NJ), maximum likelihood method (ML) and Bayesian methods (BI). As shown in Fig. 3, the sequences of HNU 2023 and the four species of the genus Leptodesmis were clustered into a phylogenetic branch, with a high bootstrap support value (100 / 73 / 1.00), indicating that HNU 2023 belongs to the genus Leptodesmis and may represent a new species of the filamentous cyanobacteria Leptodesmis. Analyses of ITS between 16 S and 23 S rRNA Gene and Secondary Structures In this study, the partial 16 S- 23 S ITS sequence of HNU 2023 was obtained with a total length of 524 bp (Table 1), and they were used, together with seven species of the five genera Leptodesmis, Kovacikia, Alkalinema, Chroakolemma and Stenomitos downloaded from NCBI, to construct the ITS secondary structures. The ITS region can be used as a tool to distinguish closely related organisms (Caires et al., 2018; Pietrasiak et al., 2014). In general, all the sequences contained both tRNAIle and tRNAAla (Table 1). Analyses of D 1 - D 1 ′ helix (Fig. 4) of the studied strains showed unique structure and different nucleotides in comparison with other Leptodesmis species. The eight related species were classified into eight types. The D 1 - D 1 ′ helix structure of the strain HNU 2023 showed that the basal stem consisted of a 5 - bp helix, followed by a 1: 8 - bp bilateral bulge, two small unidirectional bulges, and then further followed by two bilateral bulges of 4: 5 - and 3: 2 - bases, the terminal loop contained 5 - bp bases. The Box-B helix (Fig. 5) of strain HNU 2023 was similar to that of several species of similar species, such as Leptodesmis alaskaensis BACA 0748, Leptodesmis sichuanensis A 121 and Chroakolemma opaca 701 clone 2 in the basal and apical stem-loop. There was a 5 - bp helix, followed by a 1: 2 bp-base bilateral bulge, in the basal stem of strain HNU 2023, and the apical structures contained a 5 - bp helix with a 4 - bp loop. No regular patterns were found for the V 3 helices between HNU 2023 and the other seven filamentous species (Fig. 6). The studied strain HNU 2023 had a 3 - bp helical basal stem, followed by four bilateral bulges (4: 4 -, 1: 1 - and two 1: 2 - bases), and the apical structures contained a 9 - bp helix with a 3 - bp loop, which significantly differed from that of species.	en	Liu, Yang, Zhang, Yang, Wang, Xue, Geng, Ruozhen, Zhang, Bangjun (2024): Description of a novel filamentous cyanobacterial species of Leptodesmis (Leptolyngbyaceae, Cyanobacteria) in China based on the polyphasic approach. Phytotaxa 678 (2): 96-108, DOI: 10.11646/phytotaxa.678.2.1, URL: https://doi.org/10.11646/phytotaxa.678.2.1
