Research Article |
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Corresponding author: Yi-Hua Tong ( yh-tong@scbg.ac.cn ) Academic editor: Wei Lim Goh
© 2025 Zheng-Yang Niu, Lin Bai, Yi-Hua Tong, Nian-He Xia.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Niu Z-Y, Bai L, Tong Y-H, Xia N-H (2025) Indosasa fimbriligulata (Poaceae, Bambusoideae), a new bamboo species from Guangxi, China. PhytoKeys 265: 209-221. https://doi.org/10.3897/phytokeys.265.167921
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Based on morphological and molecular phylogenetic evidence, we confirmed that some bamboo collections from Guangxi, China, represent a new species of Indosasa. The new species, named I. fimbriligulata, is morphologically similar to I. glabrata but differs by having internodes that are white strigose when young, and hollow without or with a little clastic pith, culm buds triangular, culm leaf sheaths abaxially scattered with tufted brown setae, culm leaf auricles well developed, and culm leaf ligule apex long fimbriate. A detailed description, as well as two color plates of this new species, is also provided.
Arundinarieae, morphology, phylogeny, taxonomy, three-branched bamboos
Indosasa McClure was established by F. A.
During two field investigations in Fangchenggang City, Guangxi, we encountered a running bamboo that does not fit the description of any known species. However, some traits, such as strongly raised culm supra-nodal ridges, strongly raised and asymmetrically swollen branch supra-nodal ridges, and the branch complement with three branches per mid-culm node, match well with those diagnostic of Indosasa s.s. After comparison with all the previously recorded species of Indosasa in national and local floras (
Morphological comparisons between this new species and morphologically similar species were conducted based on living plants in the field, specimens, protologues, and descriptions from floras (
To ascertain the phylogenetic position of this new species, we conducted phylogenetic analyses based on nuclear single-copy orthologous genes (SOGs). According to the most recent phylogenetic framework of three-branched bamboos (
For DNA extractions, young leaves were collected in the field and dried with silica gel. Total genomic DNA was extracted from the dried leaves using the Rapid Plus DNA Lib Prep Kit for Illumina (RK2008) (ABclonal, Woburn, USA) and sheared (1 μg DNA per sample) using a Covaris M220 ultrasonicator (Covaris, Woburn, USA). PCR products were purified using the AMPure XP system (Beverly, USA). Library quality was assessed on the Agilent 5400 system (Agilent, USA), and DNA quantification was performed by quantitative polymerase chain reaction (qPCR). The qualified paired-end library was pooled using the NEBNext® UltraTM DNA Library Prep Kit and sequenced on the NovaSeq 6000 platform with the PE150 strategy. After filtration of adapters and low-quality reads using Fastp software v. 0.23.2 (
For nuclear gene recovery, we used the protein-coding sequences of six previously published bamboo genomes – Dendrocalamus latiflorus Munro (
We aligned the 479 SOGs using MAFFT v. 7.505 (
We used a multi-species coalescent-based method for nuclear gene-based phylogenetic inference. We first inferred individual ML trees using RAxML v. 8.2.12 (
Our nuclear SOG-based MLB species tree strongly supported that the new species is a member of Indosasa s.s. and is closely related to I. glabrata (BS = 100) (Fig.
The multi-locus bootstrapping ASTRAL species tree shows the phylogenetic position of Indosasa fimbriligulata, which is reconciled by coalescence of 465 single-copy orthologous nuclear gene trees after collapsing branches with support values <30%. BS support values below 70% are represented by a slash.
Morphological comparison revealed that the new species is morphologically similar to I. glabrata in having small culms that are 2–4 m high and 0.5–2 cm in diam., narrow and long triangular papery culm leaf sheaths, and linear-lanceolate culm leaf blades, whereas the other Indosasa species are usually characterized by relatively large culms, leathery culm leaf sheaths, and broad lanceolate to ovate culm leaf blades. The new species can be easily distinguished from I. glabrata by having triangular (vs. oblate) culm buds, white strigose (vs. glabrous) young culm internodes, without pith or with slightly clastic pith (vs. lamellate pith), abaxial surface of culm leaf sheath with scattered clumps of brown setae and base of culm leaf sheath with dense brown setae (vs. glabrous culm leaf sheath), well-developed (vs. undeveloped) culm leaf auricles and oral setae, and culm leaf ligule with long fimbriae (vs. glabrous) (Table
Indosasa fimbriligulata N.H.Xia, Z.Y.Niu & Y.H.Tong. A. Branch complement, showing strongly raised and asymmetrically swollen branch supra-nodal ridges; B. Foliage leafy branchlets; C. Ultimate foliage leafy branchlet; D. Portion of foliage leafy branchlet showing auricles and oral setae; E. Portion of culm leaf, showing culm leaf blade; F. Culm leaf ligule with long fimbriae; G. Culm leaf sheath base. Scale bars: 5 cm (A); 10 cm (C); 5 mm (F); 1 cm (D, E, G).
Indosasa fimbriligulata N.H.Xia, Z.Y.Niu & Y.H.Tong. A. Culm leaf sheath; B. Portion of culm, showing leaf blade, node, and internode; C. Culm node, showing culm bud and sheath scar; D. Branch complement with three branches at culm node, showing strongly raised and asymmetrically swollen branch supra-nodal ridges; E. Ultimate foliage leafy branchlet. Scale bars: 2 cm (A–E).
| Characters | I. fimbriligulata | I. glabrata |
|---|---|---|
| Young culm | ||
| Primary buds | Triangular | Oblate |
| Surface of internodes | White strigose | Glabrous |
| Cavity pith | Nearly absent | Lamellate |
| Culm leaf | ||
| Abaxial surface of sheaths | Scattered with tufted brown setae | Glabrous |
| Base of abaxial surface of sheaths | Densely brown setose | Glabrous |
| Auricles | Small, ca. 0.5 × 1 mm | Undeveloped |
| Oral setae | Developed, 2–10 mm long | Undeveloped |
| Apex of ligules | Fimbriate | Glabrous |
| Blade shape | Linear to linear-lanceolate | Narrow lanceolate to lanceolate |
Although recent phylogenetic studies based on plastid and nuclear sequences confirmed that Indosasa s.l. is non-monophyletic (
China • Guangxi Zhuang Autonomous Region: Fangchenggang City, Naliang Town, Gaolin Village; 21°37'48"N, 107°40'57"E; alt. 391 m; 17 April 2025; L. Bai & H. Y. Li BLSC-25041501 (holotype: IBSC!).
Indosasa fimbriligulata resembles I. glabrata but differs from the latter in having white strigose internodes when young, hollow internodes without pith or with a little clastic pith, abaxial surface of culm leaf sheaths scattered with tufted brown setae, well-developed culm leaf auricles, and culm leaf ligule apex with long fimbriae.
Rhizomes leptomorph. Culms diffuse, erect, sometimes flexuose, 2–4 m tall and 0.5–1.5 cm in diameter; internodes flattened on branching side, with two longitudinal ridges and three grooves above branching points along the branching side, 30–50 cm long, initially green to dark green, yellow-green when aged, white strigose when young, glabrescent when old, white powdery only at infranodal regions; walls 3–4 mm thick, cavity hollow without pith or with slightly clastic pith; supra-nodal ridges strongly raised, sheath scars prominent, with a corky ring and densely brown setose when young, glabrescent when old, with persistent remains of sheath base. Branch supra-nodal ridges strongly raised and asymmetrically swollen. Primary buds solitary, triangular, yellowish green, not sunken into culm, margin densely ciliate. Branch complement with three branches at each culm node. Culm leaf sheaths initially green with small purple dots, more so on the marginal part, turning to straw when old, tardily deciduous, narrow and long triangular, papery, abaxially scattered with tufted brown setae, densely brown setose at base, margins densely ciliate; auricles small, ovate to triangular, ca. 1 × 0.5 mm; oral setae well-developed, many, straight or slightly tortuous, 2–10 mm long; ligules arcuate, ca. 2 mm tall, abaxially puberulent, apex long fimbriate, fimbriae many, straight or slightly tortuous, 3–7 mm long; blades reflexed, linear to linear-lanceolate, 0.8–3 × 0.1–0.3 cm, 3/50–6/50 as long as sheath, apex acuminate, base narrowed, adaxially sparsely brown setae, abaxially glabrous. Foliage leaves 4–7 per ultimate branchlet; sheaths 3.5–6.5 cm long, glabrous, longitudinal ribs conspicuous when dry; auricles well-developed, ovate to triangular, 3–5 × 1–3 mm; oral setae many, straight or slightly tortuous, 3–20 mm long; ligules short, truncate, 0.5–1 mm tall, abaxially pubescent; blades lanceolate, papery, 9.5–24 × 1.5–3.8 cm, apex acuminate, base cuneate to widely cuneate, glabrous on both sides, one margin serrulate, other margin entire, secondary veins 5–8 pairs, transverse veinlets conspicuous. Inflorescence unknown.
New shoots from April to June.
This new species has been found only in its type locality so far. It usually occurs on mountain slopes near roadsides and streams.
The specific epithet refers to the fimbriate culm leaf ligule of this species, which is rarely seen in other Indosasa species. Its Chinese name is given as 流苏大节竹 [liú sū dà jié zhú].
China • Guangxi: Fangchenggang City, Naliang Town, Gaolin Village; 21°37'34"N, 107°41'8''E; alt. 443 m; 15 June 2025; Z. Y. Niu, NZY297 (IBSC).
Old culms are used for fences.
We are grateful to Ms. Hong-Yan Li (South China Botanical Garden, Chinese Academy of Sciences) for her assistance during the fieldwork and to Mr. Ding-Han Cui (South China Botanical Garden, Chinese Academy of Sciences) for the line drawing.
The authors have declared that no competing interests exist.
No ethical statement was reported.
No use of AI was reported.
This study was supported by the National Natural Science Foundation of China (Grant No. 32270227), the Chinese Academy of Sciences (Biotaxonomic Scientist Post Grant No. CAS-TAX-24-049), the Basic Research Projects Independently Deployed by South China Botanical Garden, Chinese Academy of Sciences (Grant No. JCYJXM-202507), and the National Wild Plant Germplasm Resource Center.
Zheng-Yang Niu: writing original manuscript, field investigation, data analysis. Lin Bai: field investigation. Yi-Hua Tong: funding support, data acquisition, reviewing, and editing the manuscript. Nian-He Xia: supervision, funding support, reviewing, and editing the manuscript.
Zheng-Yang Niu https://orcid.org/0000-0003-0281-1504
Yi-Hua Tong https://orcid.org/0000-0002-5034-005X
Nian-He Xia https://orcid.org/0000-0001-9852-7393
All of the data that support the findings of this study are available in the main text or Supplementary Information.
465 single-copy orthologous gene alignments used for the reconstruction of MLB ASTRAL species tree and one supplementary table
Data type: zip
Explanation note: Here are 465 single-copy orthologous gene alignments used for the reconstruction of multi-locus bootstrapping ASTRAL species tree, and their corresponding specimen voucher information used in our study.