identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
0B4036FEC29054D6A36E9C68A635E34E.text	0B4036FEC29054D6A36E9C68A635E34E.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Pleurastrum gracilis Q. Yan & G. Liu 2026	<div><p>Pleurastrum gracilis Q. Yan &amp; G. Liu sp. nov.</p><p>Description.</p><p>Single cell, ranging from spherical to ellipsoidal in shape (Fig. 1 A, B). The cell wall is thin, the chloroplasts are single, the cell surface is smooth, and there is one pyrenoid (Fig. 1 A). Spores are ovate to elliptical in shape. Spherical nutrient cells can have a diameter of up to 11 μm, sporangia can reach 18 μm, and ellipsoidal nutrient cells are 9–12 μm long and 6–9 μm wide. Multiple ellipsoidal cells were observed to be connected (Fig. 1 C). The cultured cells often appear yellow green in color (Fig. 1 D). Asexual reproduction occurs by producing 8–16 zoospores through sporangia (Fig. 1 E, F). No sexual reproduction observed.</p><p>Etymology.</p><p>Species names refer to the morphology of zoospores.</p><p>Type locality.</p><p><a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=100.38333&amp;materialsCitation.latitude=36.65" title="Search Plazi for locations around (long 100.38333/lat 36.65)">Qinghai Lake</a> in Qinghai Province, China (36°39'N, 100°23'E); on the surface of the lake water.</p><p>Iconotype.</p><p>Fig. 1 A.</p><p>Holotype.</p><p>QF 2021 (HBI), collected by Qiu–Feng Yan, September 2020; deposited in the Freshwater Algal Herbarium (HBI), Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, China.</p><p>Distribution.</p><p>At present, the algal isolate is only found in China. It grows on the surface of saltwater lakes and freshwater rivers.</p><p>Authentic culture.</p><p>Culture isolate FACHB- 3463 is deposited in the Freshwater Algae Specimen Station, Institute of Hydrobiology, Chinese Academy of Sciences (http://algae.ihb.ac.cn/).</p><p>Compared with other Pleurastrum species, the isolate was found in a saline lake at high altitude. The difference between the isolate and its sisters branch was that the cell wall was thin, and a number of ellipsoid cells were observed to connect head to tail.</p><p>Phylogenetic analyses</p><p>The 18 S rDNA alignment applied 58 sequences (including 8 Pleurastrum sequences), which consisted of 1641 sites, out of which 473 (17.8 %) and 365 (12.3 %) were variable and parsimony-informative sites, respectively. 22 ITS sequences were used for alignment and 361 sites, out of which 171 (59.9 %) and 158 (42.5 %) were variable and parsimony-informative sites, respectively. Table 1 presents detailed information about the alignment and nucleotide substitution in 18 S rDNA and ITS concatenated phylogenies for molecular phylogenetic analysis.</p><p>The phylogenetic tree was constructed using the Bayesian approach based on 18 S rDNA and ITS alignments (Figs 2, 3), with the Bayesian posterior probabilities and ML bootstrap support reported. The topology of our 18 S rDNA phylogeny (Fig. 2) is essentially consistent with that reported in previous studies (Kim et al. 2025). The tree based on 18 S rDNA showed a strong Pleurastrum clade, comprising the algal isolates isolated in the present study; hence, the algal isolates were classified into the genus Pleurastrum (Fig. 2). The phylogenetic tree constructed based on ITS sequences supports the above results (Fig. 3 A).</p><p>ITS 2 secondary structure</p><p>The secondary structure of ITS 2 of P. gracilis was annotated and predicted (Fig. 3 B), and it was found that, similar to the model species, this species has a typical one ring four stem structure of eukaryotes. The differences between this species and known species within the genus were compared, with the only difference being the presence of branching structures on Helix- 1. We also constructed a maximum likelihood evolutionary tree using ITS 2 secondary structure (Fig. 4 A). The shared ITS 2 secondary structure was predicted using five species within the Pleurastrum genus (Fig. 4 B), and it was found that the four main helix regions (Helix) of these two isolates had at least one compensatory base change (CBC) compared to other species within the genus (Table 2).</p></div>	https://treatment.plazi.org/id/0B4036FEC29054D6A36E9C68A635E34E	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Pensoft via Plazi	Yan, Qiufeng;Ge, Tao;Wang, Degao;Bai, Yachen;Liu, Benwen;Hu, Jifei;Zhu, Huan;Liu, Guoxiang	Yan, Qiufeng, Ge, Tao, Wang, Degao, Bai, Yachen, Liu, Benwen, Hu, Jifei, Zhu, Huan, Liu, Guoxiang (2026): Phylogenetic and Taxonomic study of a new aquatic alga, Pleurastrum gracilis sp. nov. (Volvocales, Chlorophyta), from the Qinghai Lake. PhytoKeys 279: 255-266, DOI: 10.3897/phytokeys.279.199681
