b. Agronomy and Life Science Department, Zhaotong University, Zhaotong, Yunnan 657000, China;
c. Yunnan Academy of Biodiversity, Southwest Forestry University, Kunming, Yunnan 650224, China
Yushania P.C. Keng (1957) belongs to the subtribe Arundinariinae and is one of the most species-rich genera in the temperate woody bamboos (Poaceae, Bambusoideae) (Li et al., 2006; Vorontsova et al., 2017; Yi et al., 2008; Zhang et al., 2020). Species of Yushania, which are mainly distributed in China but also in the Himalayas, Indo-China and the Philippines, are morphologically diverse, shrubby or arborescent bamboos, with culm height ranging from 0.35 m to 7 m (Li et al., 2006). Yushania have long necked pachymorph rhizomes (up to 100 cm), branches at each node range from solitary to many, and some of which are as thick as the culm or have no secondary branches. The inflorescence is semelauctant, open and paniculate, with three stamens. Yushania was previously divided into two sections based on culm height and branch number: Yushania sect. Brevipaniculatae T.P. Yi and Y. sect. Yushania (Yi, 1986, 1995). Section Brevipaniculatae is characterized by taller culms, many and subequal branches at each node, which are obviously thinner than the culm, and terminal racemes or panicles. In contrast, species of section Yushania are shorter and have only one branch at each node or one branch at lower nodes but more than three branches at upper nodes; the diameter of branches are usually as thick as culms when only one at the node, and terminal panicles.
Yushania is distributed in the mid-elevation and subalpine mountain areas, from low hills at 500 m to high elevation mountains (up to 3800 m), and its center of diversity is in Southwest China (Keng and Wang, 1996; Li et al., 2006; Ohrnberger, 1999; Vorontsova et al., 2017; Yi, 2000; Yi et al., 2008). The species of Yushania are ecologically important because they play a role in water and soil conservation and provide food and habitat for many endangered animals, including the giant panda (Yi and Jiang, 2010).
Because of infrequent flowering (Janzen, 1976), the inflorescence of only 11 species of Yushania have been hitherto described; thus, most of the taxa are described based on the vegetative morphology (Li et al., 2006; Yang and Yi, 2013, 2014; Yi et al., 2008; Yi and Yang, 2016; Zhang et al., 2019). In 2015, several species in Yushania without flowers were collected by the authors during field investigations in Hunan Province, south-central China. The morphological character of several taxa could not be matched to any described species, and molecular analyses demonstrated that their positions on phylogenetic trees were unique (Ye et al., 2019). Here, we described two new species (referred to as Y. sp.3 and Y. sp.4, respectively, in Ye et al., 2019) based on the morphological and phylogenetic evidence, with comments on morphologically and phylogenetically related species. In addition, we revised the taxonomy of two Yushania species based on morphological comparisons in the field and herbaria, and our phylogenetic results.
2. Materials and methodsMolecular phylogeny of Yushania was reconstructed based on ddRAD-seq data (Ye et al., 2019). Measurements and morphological character assessments of the putative new species were carried out on living plants in the field and herbarium specimens. Related species were chosen from morphological comparisons and phylogenetic results, with the morphological features of these species culled from specimens and descriptions in previous studies (Keng and Wang, 1996; Li et al., 2006; Yi et al., 2008).
3. ResultsIn the ddRAD phylogeny of alpine bamboos with a broad sampling, Yushania is represented by 74 samples of 70 species covering 87.5% of the global species. A simplified phylogeny of Yushania is presented in Fig. 1, showing the phylogenetic position of the putative new species and Yushania tongpeii D.Z. Li, Y.X. Zhang & E.D. Liu, a species described recently based on the vegetative morphology (Zhang et al., 2019).
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| Fig. 1 The simplified phylogeny of Yushania based on ddRAD-seq data (adapted from Ye et al., 2019), highlighting the position of the two putative new species and Y. tongpeii, a species described recently. |
Yushania longshanensis D.Z. Li & X.Y. Ye, sp. nov.
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| Fig. 2 Yushania longshanensis D.Z. Li & X.Y. Ye. A. Habitat B & C. Individuals. |
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| Fig. 3 Yushania longshanensis D.Z. Li & X.Y. Ye. A. Rhizome B. Leaf sheaths C. Culms, showing branches and culm sheaths D. & E. Culm sheaths with a powdery white ring, showing sparsely yellow-brown setose F. Branches at lower nodes, showing 1 with long length G. Branches at upper nodes, showing 3 with no secondary branches H. Foliage leaves. |
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| Fig. 4 Yushania longshanensis D.Z. Li & X.Y. Ye. A. Individual B. Branches at the upper nodes C. Culm sheaths with sparsely yellow-brown setose D. Foliage leaves E. Leaf sheaths. |
Diagnosis. Similar to Yushania confusa (McClure) Z.P. Wang & G.H. Ye, Y. angustifolia T.P. Yi & J.Y. Shi and Y. pachyclada T.P. Yi, but differs by having a thinner culm with only 0.2—0.3 cm in diameter, glabrous sheath scar, oral setae absent, longer leaf blade (up to 20 cm) and fewer secondary veins.
Type. CHINA, Hunan, Longshan County, Da'an Township, Wanbaoshan Forest Farm Department, 29°34'10"N, 109°40'15"E, 1256 m, 19 July 2015, X.Y. Ye & J.X. Liu YXY222 (holotype & isotype: KUN!).
Description. Rhizomes pachymorph, culm neck 18—30 cm long, 0.3—0.4 cm in diameter, solid. Shrubby bamboo, 1—1.5 m tall, 0.2—0.3 cm in diameter; internodes terete, 12—23 cm long, initially sparsely purple spotted, with a white powdery ring below nodes, glabrous, nearly solid; nodes with weakly prominent supra-nodal ridge; sheath scar prominent, with persistent remains of sheath base. Branches 1 at lower nodes, up to 80 cm long, 3 at upper nodes, bearing secondary branches or sometimes none. Culm sheaths persistent, yellow-brown, 1/4—1/3 as long as internode, cartilaginous, sparsely yellow-brown setose, readily deciduous, margins brown setose; auricles and oral setae absent; ligules truncate, ca. 1 mm; blades reflexed, linear-lanceolate, deciduous. Foliage leaves 2—4 per ultimate branch; sheaths 3—5 cm long, glabrous, margins glabrous; auricles and oral setae absent or 2—3, deciduous; ligules truncate, ca. 1 mm; petioles 2—6 mm long, glabrous; blades lanceolate, 10—20 × 0.9—1.3 cm, wavy when dry, glabrous, secondary veins 3—4 pairs, transverse veins conspicuous, apex tapering, base cuneate, margins serrate. Inflorescence unknown.
Phenology. New shoots June to July.
Etymology. The specific epithet refers to the type locality, Longshan county.
Vernacular name. Lóng Shān Yù Shān Zhú (Chinese Pin-Yin transliteration); 龙山玉山竹(Chinese name).
Distribution and habitat. To date, this species is only found in Longshan County, northwest Hunan, China. This species grows with miscellaneous shrubs (Fig. 2A) from 1200 m to 1300 m in the Wanbaoshan Forest Farm.
Notes. Morphological comparison between Y. longshanensis and morphologically and phylogenetically related species (Fig. 1), Y. confusa, Y. angustifolia and Y. pachyclada is provided in Table 1.
| Character | Yushania longshanensis | Y. confusa | Y. angustifolia | Y. pachyclada |
| Culm height | 1-1.5 m | 1-2 m | 1.5-2 m | 1-2 m |
| Culm diameter | 0.2-0.3 cm | 0.2-1 cm | 0.5-0.7 cm | 0.3-1 cm |
| Internode | 12-23 cm long, a ring of white powder below nodes | 10-33 cm long, initially powdery white | (6) 16-22 cm long, a ring of white powder below nodes | 20-30 cm long, a ring of white powder below nodes |
| Branch complement | 1-3 | 1-5 | 1-3 | 1-5 |
| Sheath scar | Prominent, glabrous, with persistent remains of sheath base | Prominent, initially yellow setose | Slightly prominent, glabrous | Prominent |
| Culm sheath | Cartilaginous, sparsely yellow-brown setose, margins setose | Leathery, brown setose, margins setose | Densely brown setose, densely ciliate | Leathery, usually glabrous, margins glabrous |
| Culm sheath oral setae | Absent | Several, 1-2 mm long, readily deciduous | 1-2, 1-3 mm long, deciduous early | Absent |
| Culm sheath blade | Re flexed, linear-lanceolate, deciduous | Reflexed, linear-lanceolate or linear | Erect or reflexed, linear-lanceolate, glabrous | Reflexed, conical or linear-lanceolate, glabrous |
| Leaf number of the ultimate branch | 2-4 | 2-5 (7) | 4-8 | 2-5 |
| Leaf sheath | 3-5 cm long, glabrous, margins glabrous | (2) 3-6.5 cm long, glabrous, margins white-gray ciliate | Glabrous | - |
| Leaf oral setae | Absent or 2-3, deciduous | Several, 2-5 mm long, gray-yellow | 2-3, 3-8 mm long, erect, purple | Absent |
| Petiole | Glabrous | Densely pubescent, rarely glabrous | Glabrous | - |
| Leaf blade | 10-20 x 0.9-1.3 cm, glabrous, secondary veins 3 -4 pairs | (3) 8-13 (21.5) x 0.6-1.5 (2.1) cm, abaxially basally gray hairy, secondary veins 4-6 pairs | 10-13 x 0.6-1 cm, glabrous, secondary veins 3 -4 pairs | 6-14 x 1.1-2 cm, glabrous, secondary veins 4-6 pairs |
| Habitat | Growing with miscellaneous shrubs from 1200 m to 1300 m, Longshan, Hunan. | Widely distributed, usually under forest at elevations of 1000-2300 m. | Cultivated, 1160 m, Guiyang, Guizhou. | Usually under broadleaved evergreen forest on mountain ridges, 1700-1800 m, southern Sichuan and northeastern Yunnan. |
Yushania stoloniforma D.Z. Li & X.Y. Ye, sp. nov.
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| Fig. 5 Yushania stoloniforma D.Z. Li & X.Y. Ye A. Individual, showing 1 branch at lower nodes and scrambling character B. Branches, showing solitary branch at the basal nodes and three branches at the upper nodes C. Culm sheath with falcate auricles D. Leaf sheath, showing developed auricles and oral setae E. Rhizome F. Culms, showing branches and culm sheaths G. Nearly solid internodes H. Branchlet. |
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| Fig. 6 Yushania stoloniforma D.Z. Li & X.Y. Ye A. Individual, showing solitary branch at the basal nodes and scrambling character B. Long-necked rhizome C. Foliage leaves D. Culm sheath with falcate auricles E. Nodes with branches. |
Diagnosis. Similar to Yushania confusa, Y. pingshanensis T.P. Yi and Y. auctiaurita T.P. Yi, but differs in having shrubby scrambling clumps, thinner culm, shorter leaf sheath and fewer secondary veins.
Type. CHINA, Hunan, Longshan County, Maoping Township, Shazipo Forest Farm, 29°21'44"N, 109°30'47"E, 1094 m, 20 July 2015, X.Y. Ye & J.X. Liu YXY224 (holotype & isotype: KUN!).
Description. Rhizomes pachymorph, culm neck 20—40 cm long, 0.3—0.5 cm in diameter, internodes 0.8—0.9 cm long, solid. Culms scrambling, 2—2.5 m, 0.2—0.5 cm in diameter; internodes terete, 16—28 cm long, initially densely purple spotted, sparsely powdery white with a dense ring below nodes, glabrous, nearly solid; nodes with weakly prominent supra-nodal ridge; sheath scar prominent, with persistent remains of sheath base. Branches 1 at lower nodes, as thick as culms, 3—5 at upper nodes, have secondary branches. Shoots green, brown setose; culm sheaths persistent or tardily deciduous, leathery, longitudinal ribs prominent, triangularly narrowly rounded, 1/3—1/2 as long as internode, brown setose, margins densely brown setose; auricles falcate; oral setae 4—7, 3—4 mm long, radiating; ligules truncate, ca. 1 mm; blades erect or reflexed, linear-lanceolate. Foliage leaves 5—6 per ultimate branch; sheaths 2—4 cm long, glabrous, margins white ciliolate; auricles elliptic or absent, oral setae several, 2—5 mm long, yellow, radiating; ligules truncate, ca. 1 mm; petioles 1—3 mm long, glabrous; blades lanceolate, 5—11 × 0.7—1.5 cm, wavy when dry, glabrous, secondary veins 3—4 pairs, transverse veins conspicuous, apex tapering, base cuneate, margins serrate. Inflorescence unknown.
Phenology. New shoots July.
Etymology. The specific epithet refers to the scrambling habit.
Vernacular name. Pú Fú Yù Shān Zhú (Chinese Pin-Yin trans-literation); 匍匐玉山竹(Chinese name).
Distribution and habitat. To date, this species is only found in Longshan County, northwest Hunan, China. This species lives in the understory of cultivated fir forests at an elevation of 1100 m in the Shazipo Forest Farm.
Notes. Morphological comparison between Yushania stoloniforma and morphologically and phylogenetically related species (Fig. 1), Y. confusa, Y. pingshanensis and Y. auctiaurita is provided in Table 2.
| Character | Yushania stoloniforma | Y. confusa | Y. pingshanensis | Y. auctiaurita |
| Clumps | Scrambling | Erect | Erect | Erect |
| Culm height | 2-2.5 m | 1-2 m | 1.2-2 m | 1-2.5 m |
| Culm diameter | 0.2-0.5 cm | 0.2-1 cm | 0.5-0.75 cm | 0.3-0.8 cm |
| Internode | 16-28 cm long, sparsely white powder with a densely ring below node, nearly solid | 10-33 cm long, initially white powder, nearly solid | 13-35 cm long, a ring of white powder below nodes, wall 1.5-2.5 mm thick | 16-22 cm long, white powder below nodes, wall 1-3 mm thick |
| Branch complement | 1-5 | 1-5 | 1-3 | 1-3 |
| Sheath scar | Glabrous, with persistent remains of sheath base | Initially yellow setose | Glabrous | Initially retrorsely brown setose, with persistent remains of sheath base |
| Culm sheath | Persistent or tardily deciduous, leathery, brown setose, margins setose | Persistent, leathery, brown setose, margins setose | Persistent, densely light yellow verrucose setose abaxially, margins densely ciliate | Persistent, cartilaginous, yellow-brown setose, margins densely ciliate |
| Culm sheath auricle | Falcate | Absent | Small, oblong or falcate | Falcate, large |
| Culm sheath oral setae | 4-7, 3-4 mm long, radiating | Several, 1-2 mm, readily deciduous | 3-5, 3-6 mm long | Many, 3-6 mm long, radiating, yellow-brown |
| Culm sheath ligule | Truncate, ca. 1 mm | Truncate, ca. 1 mm | Truncate or arcuate, ca. 0.6 mm | Arcuate, ca. 0.5 mm |
| Culm sheath blade | Erect or reflexed, linear-lanceolate | Reflexed, linear-lanceolate or linear | Reflexed, triangular-linear or linear-lanceolate | Erect or decumbent, narrowly triangular or lanceolate, glabrous, margins serrulate |
| Leaf number of the ultimate branch | 5-6 | 2-5 (7) | 5-9 | 3-8 |
| Leaf sheath | 2-4 cm long, glabrous, margins white ciliate | (2) 3-6.5 cm long, glabrous, margins white-gray ciliate | 5.2-6.5 cm long, glabrous, margins glabrous | Glabrous or gray pubescent, apically white powder, margins yellow-brown ciliate |
| Leaf auricle | Elliptic | Absent | Small, purple | Purple, falcate |
| Leaf oral setae | Several, 2-5 mm long, yellow, radiating | 2-5 mm long | 4-8, yellow, 3-8 mm long | Many, 2-7 mm long |
| Leaf ligule | Truncate, ca. 1 mm | Truncate, glabrous, ca. 1 mm | Truncate, glabrous, ca. 0.3 mm | Arcuate, ca. 1 mm |
| Petiole | Glabrous | Densely pubescent, rarely glabrous | Glabrous | Abaxially occasionally white powder |
| Leaf blade | 5-11 x 0.7-1.5 cm, glabrous, secondary veins 3 -4 pairs | (3)8-13 (21.5) x 0.6-1.5 (2.1) cm, abaxially basally gray hairy, secondary veins 4-6 pairs | 9-17 x 1.3-2.2 cm, glabrous, secondary veins 6 -8 pairs | 8-16 x 1.3-3 cm, glabrous, secondary veins 5-9 pairs |
| Habitat | Under the cultivated fir forest, 1100 m, Longshan, Hunan. | Widely distributed, usually under forest at elevations of 1000-2300 m. | Under broadleaved evergreen forest on mountain ridges, 1500 -2000 m, Pingshan, Sichuan. | Under broadleaved forest, 1700-1800 m, southeast Guizhou. |
Yushania weiningensis D.Z. Li & X.Y. Ye, nom. nov.
Yushania microphylla T.P. Yi & L. Yang, J. Bamboo Res., 32: 5. 2013. nom. illeg.
Type: CHINA. Guizhou, Weining County, Xiaohai Town, Xiaozhangguan Village, 26°56'29"N, 104°6'17"E, 2300 m, 15 November 2005, Yi Tongpei 05111 (holotype, SIFS). Non Y. microphylla (Munro) R.B. Majumdar in S. Karthikeyan & al., Fl. Ind. Enum. - Monocot.: 283 (1989); non Y. microphylla (Munro) Ohrnb., Bamboos of the World Intro. 2 10 (1996), isonym. Basionym: Arundinaria microphylla Munro, Trans. Linn. Soc. London 26(1): 32 (1868).
Distribution. To date, this species is only found in Weining, Guizhou, China.
Notes. Yang and Yi described a new Yushania species from Guizhou, China, in 2013, named as Y. microphylla T.P. Yi & L. Yang (Yang and Yi, 2013). However, we found that this name (Y. microphylla (Munro) R.B. Majumdar) has been used to describe a small and shrubby bamboo distributed in northeast India, Sikkim, Khasi Hills in Meghalaya and Bhutan (Munro, 1868; Noltie, 2000; Seethalakshmi and Muktesh Kumar, 1998; Stapleton, 1994; Vorontsova et al., 2017). According to the International Code of Nomenclature for algae, fungi, and plants (Turland et al., 2018), Y. microphylla T.P. Yi & L. Yang is a latter homonym and is illegitimate. This species was sister to Yushania maculata T.P. Yi in phylogenetic trees (Ye et al., 2019). We confirmed that Y. microphylla T.P. Yi & L. Yang is an independent species after morphological comparisons of closely related species (Table 3). Therefore, we propose Y. weiningensis D.Z. Li & X.Y. Ye as a new name for Y. microphylla T.P. Yi & L. Yang. The specific epithet of the new name refers to the type locality, Weining County.
| Character | Yushania weiningensis | Y. microphylla | Y. maculata |
| Culm neck | Solid | Hollow | Solid |
| Culm height | 3-4 (5) m | 1.2 m | 2-3.5 m |
| Internode | (10)28 (35) cm, glabrous, initially white powdery | ca. 7 cm long, glabrous | 10-30 (40) cm, brown or light yellow setose, initially densely white powder |
| Nodal sheath scar | Weakly prominent | Prominent | Level or weakly prominent |
| Branches | 5-8 | Many | 7-12 |
| Leaf sheath | Striate, light-green, glabrous | Striate, dark, scabrous, fimbriate at the top | Glabrous |
| Leaf blade | 3.8-8.5 x 0.4-0.7 cm, linear-lanceolate, apex acuminate, secondary veins 2-3 pairs | 3 x 0.3 cm, linear-lanceolate, acute; secondary veins 2 pairs, inconspicuous | 9-15 x 0.9-1.1 cm, linear-lanceolate, apex acuminate, secondary veins 4 pairs |
| Distribution | Weining, Guizhou, China | Bhutan and India | Southwest Sichuan, northeast Yunnan, China |
Specimens examined. CHINA, Guizhou, Weining County, Xiaohai Town, Xiaozhangguan Village, 26°56'46"N, 104°4'58"E, 2363 m, 13 May 2015, X.Y. Ye & M.Y. Zhou YXY180 (KUN!).
Yushania elevata T.P. Yi
Yushania elevata T.P. Yi, J. Bamboo Res., 5 (1): 17. 1986. Type: CHINA. Yunnan, Tengchong County, 20 August 1983, Yi Tongpei 83142 (holotype, SIFS!).
Yushania gigantea T.P. Yi & L. Yang, Bull. Bot. Res., 31 (1): 1. 2014. syn. nov. Type: CHINA. Yunnan, Lushui County, 25°59'47"N, 98°39'41"E, 2300 m, 26 October 2005, Yi Tongpei 05080 (holotype, SIFS).
Description. Culm neck to 70 cm; internodes solid. Culms 4—7 m, 1.4—6 cm in diameter; internodes terete, 15—60 cm, glabrous or initially brown setulose below nodes; wall 3—8 mm thick; nodes with weakly prominent to prominent supra-nodal ridge; sheath scar prominent, initially brown setose. Branches 8—20, solid or nearly so. Culm sheaths persistent or gradually deciduous, narrowly triangular, ca. 1/2-2/3 as long as internodes, leathery to cartilaginous, densely yellow-brown woolly setose, margins densely brown setose, longitudinal ribs prominent; auricles absent; oral setae absent or gradually deciduous; ligules convex or rarely truncate, 1—2 mm tall, glabrous; blades linearlanceolate, 2—7 × 0.3—0.6 cm, revolute, glabrous. Foliage leaves 4—7 per ultimate branch; sheaths 2—5.5 cm long, longitudinal ribs prominent, glabrous; auricles absent; oral setae absent or several, erect or curved, brown, 0.5—6 mm; ligules convex, 0.5—1 mm tall, glabrous; petioles 1—2.5 mm long, glabrous; blades narrowly lanceolate, 3.5—20 × 0.4—1.8 cm, glabrous, secondary veins 2—4 pairs, transverse veins distinct, base cuneate, one margin serrulate, another margin smooth, apex acuminate.
Phenology. New shoots July.
Distribution and habitat. Yushania elevata occurs under the broadleaved forest or Pinus yunnanensis Franch. forest in western Yunnan, at the elevations of 2000—2300 m.
Notes. Yushania gigantea was described in 2014 by Yang and Yi (2014), and included in our phylogenetic analyses based on ddRAD-seq data (Ye et al., 2019). Results show that this species is sister to Y. elevata and obtained 100% bootstrap support. Morphological comparison of the two species revealed that they were very similar, differing only in two ambiguous features: Y. gigantea has persistent culm sheaths and a longer leaf blade (3.5—20 cm), whereas Y. elevata is tardily deciduous and has a shorter leaf blade (4.5—9.5 cm) (Keng and Wang, 1996; Li et al., 2006; Yang and Yi, 2014). Most Yushania species are short and shrubby; only few can grow into arborescent plants (about six species). Moreover, the holotype specimen of Y. gigantea was collected from Lushui, western Yunnan, China, at an elevation of 2300 m, which is in the distribution range of Y. elevata (2000—2300 m in western Yunnan) (Keng and Wang, 1996; Li et al., 2006). It is unlikely that two arborescent species occur in a narrow area. Together with their close relationship and similar morphology, we conclude that Y. gigantea and Y. elevata are conspecific, and Y. gigantea is treated to be a new synonym of Y. elevata.
Specimens examined. CHINA, Yunnan, Lushui County, Wuzhong Village, 26°07'03"N, 98°35'43"E, 2061 m, 8 May 2011, ZXZ11010 (KUN!); CHINA, Yunnan, Lushui County, Wuzhong Village, 26°03'12"N, 98°36'53"E, 2206 m, 8 May 2011, ZXZ11012 (KUN!); CHINA, Yunnan, Lushui County, along the Pianma Road between 72 and 73 km, 25°59'55"N, 98°39'39"E, 2429 m, 6 August 2014, X.Y. Ye & W.H. Wang YXY134 (KUN!).
4. DiscussionYushania longshanensis (i.e., Y. sp.3 in Fig. 2 in our previous work) (Ye et al., 2019) and Y. stoloniforma (i.e., Y. sp.4 in Fig. 2 in our previous work) (Ye et al., 2019) are here assigned to Yushania sect. Yushania based on morphological features: solitary branch at the base nodes and three to five branches at the upper nodes, and culms with short or medium height.
Yushania longshanensis is most similar to Y. angustifolia and Y. pachyclada according to morphological characteristics, but can be distinguished by some subtle features: thinner culms (only 0.2—0.3 cm in diameter), sparsely yellow-brown setose, larger leaf blade and type of habitat where distributed. Moreover, molecular phylogenetic analyses indicate that Y. longshanensis is distantly related to Y. angustifolia (Ye et al., 2019). In addition, phylogenetic analysis shows that Y. longshanensis is related to Y. stoloniforma and Y. confusa. However, Y. longshanensis and Y. stoloniforma have different growth habit; furthermore, Yushania longshaneneis and Y. confusa can be distinguished by the presence versus absence of hair on the sheath scar, petiole and leaf blade.
Yushania stoloniforma is morphologically similar to Y. pingshanensis and Y. actiaurita. They all have less than five branches at the node, medium culm height, prominent sheath scar, persistent culm sheath, several radiating culm sheath oral setae and reflexed culm sheath blade, but Y. stoloniforma can be easily distinguished from them by its different growth habit, the smaller leaf size and the different arrangement of the leaf blade. Phylogenetic topology indicates that Y. stoloniforma has a sister relationship with Y. confusa (Ye et al., 2019) although the two species have different morphological features, with Y. stoloniforma having scrambling growth habit, glabrous sheath scar, developed culm sheath auricles with radiating oral setae, and glabrous petiole and leaf blade.
Most species of Yushania are distributed in the Hengduan Mountains region and may have begun migrating southward during the late Pliocene (Ye et al., 2019). The migration route of Yushania passes through the Yunnan-Guizhou Plateau, adjacent to Hunan province. Therefore, the discovery of Y. longshanensis and Y. stoloniforma, which are endemic to the Hunan province, provides a means for studying the origin and diversification of Yushania, and may also help to understand the evolutionary history of bamboos distributed in southwestern China. In addition, the discovery of Y. longshanensis and Y. stoloniforma calls attention to these two ecologically important species, which play a role in soil protection and provide food and habitat for animals, including many endangered species.
Author contributionsXYY conducted the field and phylogenetic work and drafted this paper; YXZ revised the draft; DZL conceived and wrote this paper.
Declaration of competing interestThe authors have no conflicts of interest to declare.
AcknowledgementsWe thank Jing-Xia Liu of Kunming Institute of Botany, Chinese Academy of Sciences, and staff of Wanbaoshan Forest Farm and Shazipo Forest Farm for their assistance in the fieldwork. The study was funded by the National Natural Science Foundation of China (nos. 31800315, 31430011), and the Applied and Fundamental Research Foundation of Yunnan Province (2019FD059).
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