A new bamboo species, Yushania dezhui, from Kunming, Yunnan, China is described and illustrated in this paper. The new species used to be misidentified as Y. polytricha. Based on careful comparison of morphological features and molecular phylogeny evidence, we confirmed its identity as a new member of the genus Yushania. Yushania dezhui resembles Y. maculata, Y. polytricha and Y. weixiensis in several aspects, such as culm height and branch complement structure. However, the glabrous culm leaf sheaths and internodes, the absence of auricles and oral setae on most foliage leaves, except the one-year-old foliage leaves, the pubescence on the adaxial surface of the one-year-old foliage leaves and its limestone habitat preference can readily distinguish this new species from its related taxa. Moreover, we emphasise that individuals from various populations and molecular markers with different inheritance patterns for phylogeny reconstruction should be included in new species discovery, especially in plant groups with complex evolutionary histories.

Limestone montane area, long-necked rhizome, new taxon, temperate woody bamboos

Yushania P.C. Keng is a genus diversified within the Hengduan Mountains region and followed by subsequent spreading outside this region (Ye et al. 2019). It belongs to the subtribe Thamnocalaminae of the tribe Arundinarieae (Poaceae, Bambusoideae) (Zhang et al. 2020) and consists of more than 90 species (Vorontsova et al. 2017; Shi et al. 2022). Taxa of Yushania are usually distributed in mountainous areas above an elevation of 1000 m and most of them are narrowly endemic to a certain region (Li et al. 2006). Due to the special habitat and distribution pattern, new species of Yushania are continuously being described recently from different mountains, such as Y. tongpeii D.Z. Li, Y.X. Zhang & E.D. Liu (Zhang et al. 2019), Y. longshanensis D.Z. Li & X.Y. Ye (Ye et al. 2021b), Y. stoloniforma D.Z. Li & X.Y. Ye (Ye et al. 2021b), Y. doupengshanensis Y.Y. Zhang et N.H. Xia (Zhang and Xia 2021), Y. tongziensis N.H. Xia, Y.Y. Zhang & G. Xie (Zhang et al. 2023).

There are two Yushania species recorded in Kunming, Yunnan, China, i.e. Y. maculata T.P. Yi and Y. polytricha T.P. Yi (Sun et al. 2003). The type specimen of Y. polytricha was collected at the Qiongzhu Temple in the west of Kunming (Yi 1986). During field investigations in recent years, we found a species of Yushania occurring in western and northern Kunming, sometimes sympatric with Y. maculata and Y. polytricha. This species has been misidentified as Y. polytricha for many years in floristic treatments and community ecology papers. The short and thin culms of this species resemble Y. polytricha, but the branches, auricles of culm leaves and foliage leaves and hairs on the culms, culm leaves and foliage leaves differ significantly from those of Y. polytricha. In order to clarify the identity of this species, we performed several field surveys at different times and localities during 2023. We finally confirm that it is new to science based on morphological and molecular evidence and describe it in this paper.

The new species (Yushania dezhui), Y. maculata and Y. polytricha all have solid rhizome necks, while Y. weixiensis possesses hollow ones. The culm height of Y. dezhui, Y. polytricha and Y. weixiensis is usually less than 2 m, whereas Y. maculata is more than 2 m tall. The internode and sheath scar of Y. dezhui are glabrous, which is different from the other three related species, which have at least some hairs on the internode and sheath scar. Dark purple-brown spotted culm leaf sheaths and purple oral setae differentiate Y. maculata from Y. dezhui. Auricles and oral setae of culm leaves and foliage leaves of Y. dezhui are usually absent, while Y. polytricha has conspicuous auricles and oral setae. Moreover, a different branch number per node and setae on culm leaves and foliage leaves can also distinguish Y. dezhui from Y. polytricha (see Table 2 for details). Although Y. dezhui and Y. weixiensis both have relatively short culms, usually glabrous culm leaves without auricles and oral setae and similar branch numbers, characters of rhizome neck, internode and foliage leaf can differentiate these two species (see Table 2 for details).

The length of the eight newly-sequenced plastomes ranged from 139599 bp (Y. shuichengensis T.P. Yi & L. Yang LPS15) to 139653 bp (the new species Y. dezhui XS01), with a consistent GC content of 38.90%. They showed a typical quadripartite circular structure, which consisted of a pair of inverted repeat regions (IR), one large single copy region (LSC) and one small single copy region (SSC). The plastome length of the new species varied from 139616 bp (ZSC03) to 139653 bp (XS01). The newly-assembled eight nrDNA sequences had a length from 8337 bp in Y. shuichengensis (LPS22) to 9010 bp in Y. polytricha (QZS001) and comprised of 18S (1811 bp), ITS1 (215–216 bp), 5.8S (165 bp), ITS2 (215–217bp), 26S (3392 bp) and an intergenic spacer (IGS, 2539–3212 bp). For the new species, individuals ZSC03 and CCS03 had the same length (8695 bp) of nrDNA sequences, while the length of the individual XS01 was four bp longer than the individual DSTQ02 (216 bp vs. 217 bp in the ITS2 region and 2898 bp vs. 2893 bp in the IGS region).

After alignment, the plastome sequences had a total length of 143257 bp, including 3994 variable sites and 783 parsimony informative sites. In the plastome tree, six lineages were recovered with high support, i.e. clades III-VI, clades IX and XI (Fig. 1). The four samples of the new species were nested within the clade V and formed two subclades. One subclade consisted of individuals ZSC03 and CCS03 (MLBP/BI = 98/1.00) and the other clade included individuals XS01 and DSTQ02 (MLBP/BI = 100/1.00). The new species had close relationships with Fargesia nivalis T.P. Yi & J.Y. Shi, Yushania maculata, Y. niitakayamensis (Hayata) P.C. Keng, Y. polytricha and Y. shuichengensis (LPS22).

Figure 1. 

Maximum Likelihood phylogenetic tree reconstructed from plastome sequences of the tribe Arundinarieae. Numbers along branches indicate the Maximum Likelihood bootstrap values (MLBP) and Bayesian posterior probabilities (BI). * means MLBP/BI=100/1.00. The Roman numbers on the right of this tree correspond to those lineages recovered in previous studies (Yang et al. 2013). The branch in red (MLBP/BI = 88/1.00) denotes the clade containing Yushania dezhui and its relatives.

The aligned length for nrDNA sequences was 13004 bp with 2571 variable sites and 1502 parsimony informative sites. In the nrDNA topologies, five subtribes were revealed, including subtribes Ampelocalaminae, Arundinariinae, Gaoligongshaniinae, Hsuehochloinae and Thamnocalaminae (Fig. 2). All the four individuals of the new species were grouped into a clade (MLBP/BI = 100/1.00) and nested in the subtribe Thamnocalaminae.

Figure 2. 

Phylogenetic tree reconstructed from nrDNA sequences of the tribe Arundinarieae by using the Maximum Likelihood method. Numbers along branches indicate the Maximum Likelihood bootstrap values (MLBP) and Bayesian posterior probabilities (BI). * means MLBP/BI = 100/1.00.

Taxonomic treatment

 Yushania dezhui Y.X.Zhang & R.L.Zhang, sp. nov.

urn:lsid:ipni.org:names:77346804-1

Figs 3, 4, 5

Diagnosis

Yushania dezhui resembles Y. maculata T.P. Yi, Y. polytricha Hsueh & T.P. Yi and Y. weixiensis T.P. Yi, but differs in having rhizome necks much thicker than culms, glabrous culm leaf sheaths, internodes and sheath scars, auricles and oral setae of most foliage leaves usually absent and the one-year-old foliage leaves with pubescence adaxially.

Figure 3. 

Yushania dezhui Y.X.Zhang & R.L.Zhang A clump B foliage leafy branch C branches D internode and culm leaf.

Type

China • Yunnan: Kunming City, Panlong District, Ciba Town, Changchong Hill; 25°07'28.87"N, 102°42'17.41"E; 2226 m a.s.l.; 22 August 2023; Y.X. Zhang et al. CCS03 (holotype, KUN!; isotype, IBSC!).

Figure 4. 

Habitats of Yushania dezhui Y.X.Zhang & R.L.Zhang A Changchong Hill, voucher No. CCS03 B Xiaoshao Village, voucher No. XS02 C Haikou, voucher No. ZSC03 D Xundian, voucher No. DSTQ02. Photos by Yu-Xiao Zhang.

Description

Rhizomes pachymorph, necks 2–30 cm long, 0.5–1.2 cm in diameter, internodes 0.2–1 cm long, solid. Culms diffuse, 0.4–1.8 m tall, 1–5 mm in diameter, subsolid; internodes 2.5–21.5 cm long, terete, purple-spotted initially, slightly white powdery below the nodes; nodes slightly prominent; sheath scars corky. Branches 3–12, slender and equal. Culm leaves tardily deciduous, ca. 1/2 as long as the internode; sheaths glabrous abaxially, green or purple apically, margins ciliate, occasionally white pubescent at the base; auricles linear or absent, usually present on upper culm leaves; oral setae several when auricles present; ligules truncate, 1–2 mm tall, green or purple, margins ciliate or not; blades linear, recurved, glabrous, 0.3–2.3 cm long. Foliage leaves 3–5 per ultimate branch; sheaths glabrous, green, purple or purple-green, 2.5–5.2 cm long, margins glabrous; auricles and oral setae usually absent, except present on the one-year-old foliage leaves, auricles linear, green or purple; ligules truncate, 1–2 mm tall, green or purple; blades 2.5–12.5 × 0.5–1.3 cm, pubescent adaxially for the one-year-old blades, glabrescent later, glabrous abaxially, secondary veins 2–4-paired, transverse veins conspicuous, margins serrate on both sides. Inflorescence unknown.

Figure 5. 

Yushania dezhui Y.X.Zhang & R.L.Zhang A foliage leaves with green sheath B foliage leaves with purple sheath C, D branches E internode with culm leaf F the one-year-old foliage leaf blade, showing the pubescent adaxial epidermis, ab = abaxial epidermis, ad = adaxial epidermis G auricles, oral setae and ligule of the one-year-old foliage leaf, a = auricles, l = ligule, s = oral setae. Photos A–E by Yu-Xiao Zhang F, G by Shun-Shun He.

Phenology

New shoots June to August.

Distribution and habitat

This new species is found in Kunming, Yunnan, China. It usually occurs in limestone montane areas at elevations of 2100–2400 m in the understorey of forests of Quercus longispica (Handel-Mazzetti) A. Camus, Castanopsis delavayi Franchet or Cupressus sp.

Etymology

The epithet honours Professor De-Zhu Li of Kunming Institute of Botany, Chinese Academy of Sciences, who has made great contributions to the taxonomy, molecular phylogeny, evolution and biogeography of bamboos and promoted the collaboration of bamboo research around the world.

Chinese name

Dé Zhū Yù Shān Zhú (Chinese pronunciation), 德铢玉山竹 (Chinese characters).

Additional specimens examined (paratypes)

China – Yunnan Province, Kunming City • Panlong District, Ciba Town, Changchong Hill; 25°7'31.85"N, 102°42'25.13"E; 2211 m a.s.l.; 26 June 2023; Y.X. Zhang & C. ZhangCCS01 (KUN); • same collection data as for preceding; 25°6'55.28"N, 102°42'5.67"E; 2314 m a.s.l.; 27 August 2023; R.L. Zhang et al. CCS04 (KUN); • same collection data as for preceding; 25°7'6.86"N, 102°42'9.98"E; 2310 m a.s.l.; 27 August 2023; R.L. Zhang et al. CCS05 (KUN); • Panlong District, Ciba Town, Xiaoshao Village; 25°11'12.22"N, 102°44'41.14"E; 2243 m a.s.l.; 27 June 2023; Y.X. Zhang & C. Zhang XS01 (KUN); • same collection data as for preceding; 25°11'10.32"N, 102°44'43.1"E; 2266 m a.s.l.; 27 June 2023; Y.X. Zhang & C. Zhang XS02 (KUN); • Xishan District, Haikou Forest Farm; 24°50'50.09"N, 102°36'19.75"E; 2147 m a.s.l.; 18 August 2023; Y.X. Zhang & R.L. Zhang ZSC02, ZSC03 (KUN); • same collection data as for preceding; 2106 m a.s.l.; 25 July 2020; H. Peng PHHK112 (KUN); • Xundian County, Xianfeng Town; 25°31'12.79"N, 103°04'28.80"E; 2429 m a.s.l.; 21 August 2023; Y.X. Zhang et al. DSTQ02 (KUN).

The branch number per node of the new species Yushania dezhui is 3–12, which is similar to Y. maculata and Y. weixiensis. In Flora Reipublicae Popularis Sinicae (Yi 1996), Yushania was divided into two sections, i.e. section Brevipaniculatae T. P. Yi and section Yushania. Taxa of the former section usually possess many branches per node, whereas species of the latter one have solitary branch or one branch on lower nodes and 3–5(-8) on middle and upper nodes. Therefore, we place Y. dezhui into section Brevipaniculatae. The most unique morphological character of Y. dezhui is the adaxial epidermis with pubescence for the one-year-old foliage blades. Up to now, there are no more than 20 bamboo species with hairy adaxial epidermis of foliage blades recorded in China, such as Bambusa polymorpha Munro, Yushania qiaojiaensis Hsueh & T. P. Yi (Li et al. 2006; Shi et al. 2022). Besides those morphological features (Table 2) that can differentiate Y. dezhui from sympatric species Y. maculata and Y. polytricha and morphologically similar species Y. weixiensis, the habitat preference is another diagnostic character. The new species Y. dezhui usually occurs in limestone montane areas from 2100 m to 2400 m a.s.l., while Y. maculata and Y. weixiensis are usually distributed on non-limestone shady slopes and at a slightly higher elevation than the new species (2200–3500 m) and Y. polytricha occurs at elevations from 1900 m to 1950 m (2000 m) (Li et al. 2006; Shi et al. 2022).

In the plastome phylogenetic analyses, the recovered six main lineages, i.e. clades III–VI, clades IX and XI, were consistent with previous studies (Guo et al. 2021). The relationships amongst the five subtribes in the nrDNA tree were not well resolved, which was also consistent with Guo et al. (2021). The four individuals of Yushania dezhui were grouped into two subclades in the plastome tree (Fig. 1), whereas they formed a clade with high support (100%) in the nrDNA tree (Fig. 2). A similar situation applied to Y. shuichengensis. Discordance between plastome and nuclear gene trees has been recovered in the genus Yushania and other genera, even in the tribe Arundinarieae (e.g. Zhang et al. (2012); Yang et al. (2013); Guo et al. (2019); Guo et al. (2021); Ye et al. (2021a)). The cytonuclear incongruence was mostly caused by the complex evolutionary history of those taxa, including hybridisation, introgression, incomplete lineage sorting and so on. Ye et al. (2021a) revealed the reticulate evolutionary history of the genera Fargesia Franchet and Yushania, based on genome skimming and double digest restriction-site-associated DNA sequencing data. In their study, only several species with multiple individuals were clustered as monophyletic and most species with multiple individuals were resolved as polyphyletic in the plastome trees. Our results referring to Y. dezhui and Y. shuichengensis were consistent with Ye et al. (2021a). In the DNA barcoding study of Fargesia, the nrDNA sequences showed better discriminatory power than the plastomes and some species recovered as polyphyletic in the plastome trees were resolved as monophyletic in the nrDNA phylogenies (Lv et al. 2023). The cases of Y. dezhui and Y. shuichengensis were also congruent with that of Fargesia. However, the specific reasons for the cytonuclear incongruence of Y. dezhui and Y. shuichengensis need to be tested within a more comprehensive sampling background in the future. On the whole, all the aforementioned studies, including our own, have demonstrated that it was better to exploit molecular markers with different inheritance patterns in discovering new species, especially those with complicated evolutionary histories.

We are grateful to Professor Lynn G. Clark of Iowa State University, USA, for polishing the manuscript and Professor Hua Peng of Kunming Institute of Botany, Chinese Academy of Sciences (CAS) and Dr. Jun Hu of Chengdu Institute of Biology, CAS for providing some geographic information in the field. We also thank Misses Na Su, Run-Lian Li and Shun-Shun He for their help in sampling or microphotography and Ms Ling Wang of Kunming Institute of Botany, CAS for the illustration.