A new genus of temperate woody bamboos (Poaceae, Bambusoideae, Arundinarieae) from a limestone montane area of China
A new genus of temperate woody bamboos (Poaceae, Bambusoideae, Arundinarieae) from a limestone montane area of China
Yu-Xiao Zhang 0 1
Peng-Fei Ma 1
De-Zhu Li 1
0 Yunnan Academy of Biodiversity, Southwest Forestry University , Kunming, Yunnan 650224 , China
1 Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences , Kunming, Yunnan 650201 , China
Ampelocalamus calcareus is a climbing and slender bamboo, known from south Guizhou, China. This species grows in broadleaved forests of limestone montane areas. Recent molecular phylogenetic analyses demonstrated that A. calcareus was sister to all other lineages of the tribe Arundinarieae rather than a member of Ampelocalamus. The morphological features and habitats of A. calcareus and related genera including Ampelocalamus, Drepanostachyum and Himalayacalamus were compared and discussed. The characteristics of the branch complements, nodes and foliage leaves distinguish A. calcareus from morphologically similar taxa. On the basis of molecular and morphological evidence, we propose to establish a new genus, Hsuehochloa, to accommodate A. calcareus and to honour the late Chinese bamboo taxonomist Chi-Ju Hsueh (Ji-Ru Xue). In addition, we describe the inflorescence of Hsuehochloa for the first time.
eol>Ampelocalamus; climbing bamboos; Hsuehochloa; new genus
Temperate woody bamboos or the tribe Arundinarieae (Bambusoideae, Poaceae)
comprise approximately 550 species in 31 genera
(BPG 2012, Clark et al. 2015)
. They are
mainly distributed in temperate to subtropical montane areas of East Asia (Ohrnberger
Copyright Yu-Xiao Zhang et al. 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.
1999) with China as the centre of species diversity (Li et al. 2006), but also in
Southeast Asia, south India, Sri Lanka, North America and Africa.
The recent plastid molecular phylogenetic results indicated that there were 12
major lineages in temperate woody bamboos, i.e. I. Bergbambos, II. Oldeania, III.
Chimonocalamus, IV. Shibataea clade, V. Phyllostachys clade, VI. Arundinaria clade, VII.
Thamnocalamus, VIII. Indocalamus wilsonii, IX. Gaoligongshania, X. Indocalamus
sinicus, XI. Ampelocalamus calcareus and XII. Kuruna. However, relationships amongst
them remain largely uncertain
(Triplett and Clark 2010, Zeng et al. 2010, Yang et al.
2013, Attigala et al. 2014, 2016, Ma et al. 2014, Zhang et al. 2016, Zhang et al. 2017)
Those lineages are strongly inconsistent with the morphological classification at the
generic and subtribal levels
(Keng and Wang 1996, Li 1997, 1999, Ohrnberger 1999)
Most species and genera were nested within lineages IV, V and VI, while some lineages
included only one species (lineages I, VIII, IX, X, XI). Lineages I and IX consisted
of Bergbambos tessellata (Nees) Stapleton and Gaoligongshania megalothyrsa
(HandelMazzetti) D. Z. Li, Hsueh & N. H. Xia, respectively and Bergbambos Stapleton and
Gaoligongshania D. Z. Li, Hsueh & N. H. Xia are both monotypic
. Lineages VIII and X were formed by Indocalamus wilsonii (Rendle) C.
S. Chao & C. D. Chu and I. sinicus (Hance) Nakai, respectively, with I.?sinicus as the
lectotype of the genus Indocalamus Nakai. Ampelocalamus calcareus C.?D. Chu & C. S.
Chao (lineage XI) was recovered as the sister taxon to all the other temperate woody
(Yang et al. 2013, Ma et al. 2014)
. The phylogenetic positions of the
abovementioned five monotypic lineages have also obtained some support from nuclear gene
(Zhang et al. 2012, Yang et al. 2013)
Molecular phylogenetic results provide fresh perspectives for taxonomy, especially
for lineages VIII, X and XI with only one species. Continuing to include these
bamboos in the present genera renders these genera polyphyletic and causes problems when
describing or citing them. In this paper, we propose to establish a new genus for
Ampelocalamus calcareus based on morphological characters and previous molecular results.
For the other two monotypic lineages (VIII and X), taxonomic revisions will be made
in a separate paper.
Materials and methods
Drepanostachyum P. C. Keng and Himalayacalamus P. C. Keng are morphologically
close to Ampelocalamus S. L. Chen, T. H. Wen & G. Y. Sheng
(Li et al. 1996)
three genera all have pachymorph rhizomes, prominent or conspicuous nodal sheath
scars and pendulous culms. Sometimes it is difficult to see the difference when only the
vegetative features are available. Some species of Ampelocalamus were transferred from
the genus Drepanostachyum
(Keng and Wang 1996, Stapleton et al. 2005, Li? et? al.
and several taxa of Drepanostachyum were combined into Himalayacalamus
(Stapleton 1994). It is necessary to compare characters of Ampelocalamus calcareus with
those two genera in order to clarify their morphological similarities and differences.
The type specimen of Ampelocalamus calcareus was examined at the herbarium of
Nanjing Forestry University (NF). We also examined specimens of A. calcareus, other
species of Ampelocalamus, Drepanostachyum and Himalayacalamus at herbaria of Kunming
Institute of Botany, Chinese Academy of Sciences (KUN), Nanjing University (N),
Institute of Botany, Chinese Academy of Sciences (PE) and Sichuan Agricultural
University, Dujiangyan Campus (SIFS) (specimens of N and PE were checked through the
Living plant observation
In 2010, one clump of Ampelocalamus calcareus was introduced by P. F. Ma and Z. M. Cai
from Libo, Guizhou and cultivated at the greenhouse of the Germplasm Bank of Wild
Species (GBOWS), Kunming Institute of Botany, Chinese Academy of Sciences,
Kunming. This introduced clump flowered between 2012 and 2013. Unfortunately, the clump
did not grow well and only a small piece of inflorescence was collected before it died. After
fieldwork in early 2015, it was confirmed that the wild populations also flowered and died
during the same period. More seedlings were introduced into the greenhouse of GBOWS
at Kunming by C. Guo and Y. Guo in March 2015. They grew well in the greenhouse
and became mature individuals after three years. Vegetative features including culms, culm
sheaths, branch complements and foliage leaves were observed based on those individuals.
Four reproductive characters and 15 vegetative characters were selected and compared
across Ampelocalamus calcareus, Ampelocalamus, Drepanostachyum and
Himalayacalamus. For A. calcareus, the morphological data were observed and obtained based on
herbarium specimens, living plants and literature. We observed and measured the
structure of the inflorescence of A. calcareus by hand lens (30?) and stereomicroscope
(Leica M166FC) without dissecting the spikelet due to the scarcity of materials. For
the other genera, the morphological data were obtained from specimens and literature.
The habitats of Ampelocalamus calcareus, Ampelocalamus, Drepanostachyum and
Himalayacalamus were also compared based on literature.
Morphological characteristics and habitat data are summarised in Table 1.
Ampelocalamus calcareus and species of Ampelocalamus, Drepanostachyum and Himalayacalamus
are all unicaespitose. Culms of A. calcareus are procumbent or scrambling, while culms
Subulate roerflleinxeedar, erect or Suobrulraedtfeleecoxiredduli,norueeasard,ielyrect
of Ampelocalamus, Drepanostachyum and Himalayacalamus are pendulous or seldom
scrambling. The characteristics of culm sheaths, internodes, branch complements,
nodal sheath scars and foliage leaves are variable across A. calcareus, Ampelocalamus,
Drepanostachyum and Himalayacalamus.
The inflorescence of Ampelocalamus calcareus is semelauctant and racemose. The
spikelet has five florets and the floret possesses a purple-green lemma (ca. 1 cm long),
palea shorter than the lemma (ca. 0.8 cm long), three purple stamens (4 mm long)
and two plumose stigmas. The inflorescence of Ampelocalamus, Drepanostachyum and
Himalayacalamus has been described in detail in other literature
(e.g. Stapleton 1994,
Li et al. 2006)
, therefore, we only list some key features in Table 1.
Analysis of the habitat data demonstrates that Ampelocalamus calcareus mainly
occurs under broadleaved forests of limestone areas below 1000 m; other Ampelocalamus
species grow under broadleaved forests, on stony slopes (limestone, granite or basalt)
and riverside slopes usually from 200 m to 1800 m alt.; taxa of Drepanostachyum are
usually distributed under coniferous and broadleaved mixed forests from 1300 m to
3200 m alt.; species of Himalayacalamus occur under temperate forests from 1200 m
to 3000 m alt. (Table 1).
Ampelocalamus calcareus was described by
Chao and Chu (1983)
vegetative specimens. This species has pachymorph rhizomes with short necks and apically
drooping culms (Fig. 1) that are similar to other species of the genus Ampelocalamus,
especially to the type species A. actinotrichus (Merrill & Chun) S. L. Chen, T. H. Wen
& G. Y. Sheng. Moreover, the conspicuous auricles and radiate oral setae on the culm
sheath and leaf sheath are similar to A. actinotrichus as well. However, characteristics
of nodes, branch complements and leaf blades are quite different from
Ampelocalamus. Ampelocalamus calcareus has inconspicuous nodal sheath scars, a solitary branch
at the base and 3?7 subequal branches at the middle and upper parts of the culm and
leathery leaf blades. Other taxa in Ampelocalamus usually possess prominent nodal
sheath scars with a corky collar, many branches with a central dominant one that may
replace the culm and papery leaf blades. Branches at the nodes of A. calcareus are long
(50?100?cm), pendulous and nearly as thick as the culm, which makes culms
scrambling or procumbent. There are also some other vegetative features that can distinguish
A. calcareus from typical Ampelocalamus species, as summarised in Table 1.
Culms of Drepanostachyum and Himalayacalamus are distally pendulous, but not
scrambling, which is different from Ampelocalamus calcareus. Branches on mid-culms
of Drepanostachyum and Himalayacalamus are usually more than 15 in number and
subequal without a central dominant one, while A. calcareus has no more than 10
subequal branches. Culm sheaths of Drepanostachyum and Himalayacalamus are usually
deciduous and glabrous abaxially, whereas culm sheaths of A. calcareus are persistent
and densely white pubescent abaxially. Ampelocalamus calcareus has conspicuous
auricles and oral setae on culm sheaths and leaf sheaths and ovate-lanceolate culm blades,
while auricles and oral setae are often absent and culm blades are subulate or linear in
Drepanostachyum and Himalayacalamus.
Due to the incomplete nature of the flowering material (Fig. 1), the description
and comparison provided in Table 1 may not be fully accurate for healthy individuals
flowering in the wild. The type of inflorescence of A. calcareus is similar to
Himalayacalamus (racemose); the number of florets per spikelet is similar to Ampelocalamus and
Drepanostachyum (5 vs. 2?7); they all have three stamens and two plumose stigmas, but
the anther colour of A. calcareus is purple while anthers are yellow in Ampelocalamus,
Drepanostachyum and Himalayacalamus.
Through comparison of morphological characters, we conclude that
Ampelocalamus calcareus morphologically resembles species of Ampelocalamus, Drepanostachyum
and Himalayacalamus in its pachymorph rhizomes and is especially similar to
Ampelocalamus in its climbing habit. However, the branch complements and the
characteristics of its nodes, culm sheaths and foliage leaves can distinguish this species from all
taxa in these three genera. The inflorescence of A. calcareus is also similar to these three
genera (on the basis of our incomplete material) in its semelauctant structure, the
presence of three stamens and two stigmas.
Molecular phylogenetic studies indicated that Ampelocalamus, Drepanostachyum and
Himalayacalamus had a close relationship in nuclear gene based phylogenies, although
only limited taxa of those genera were sampled
(Yang et al. 2013)
Ampelocalamus calcareus was sister to all the other taxa of the tribe Arundinarieae in plastid and
nuclear gene trees
(Yang et al. 2013, Ma et al. 2014, Attigala et al. 2016, Zhang et al.
. The morphological similarity between the distantly related A. calcareus and those
three genera (Ampelocalamus, Drepanostachyum and Himalayacalamus) demonstrated
that morphological characters had undergone complex evolutionary trajectories in those
taxa and also in the whole tribe and some important features in bamboo taxonomy were
homoplastic or convergent that was illustrated in other studies of Arundinarieae and
some tropical woody bamboos
(Yang et al. 2008, Tyrrell et al. 2012, Attigala et al. 2016)
The habitat and altitude of A. calcareus are more similar to other typical species
of Ampelocalamus than they are to Drepanostachyum and Himalayacalamus (Table 1).
Based on the above analysis of morphology, molecular phylogenetic relationships and
habitat, we propose to establish a new genus to accommodate Ampelocalamus calcareus.
Hsuehochloa D. Z. Li & Y. X. Zhang, gen. nov.
Diagnosis. Hsuehochloa resembles genera Ampelocalamus, Drepanostachyum and
Himalayacalamus, but differs from those genera by its thin culms (4?5 mm), fewer branches
in each branch complement (1, 3?7), inconspicuous nodal sheath scar, falcate auricles
and leathery foliage leaves.
Type. Hsuehochloa calcarea (C. D. Chu & C. S. Chao) D. Z. Li & Y. X. Zhang,
comb. nov. (77190834-1)
Basionym. Ampelocalamus calcareus C. D. Chu & C. S. Chao, Acta Phytotax. Sin.
21: 204?206. 1983. Type: CHINA, Guizhou, Libo, 500 m, C. D. Chu, C. S. Chao, J.
Q. Zhang & K. M. Lan 81018 (holotype, NF!; isotype, PE!)
Description. Rhizomes pachymorph. Culms caespitose, apically drooping,
procumbent or scrambling, 4?6 m long, 4?5 mm in diameter, internodes terete, 8?18
cm long, densely white pubescent initially at the upper part, later subglabrous; nodes
and sheath scars inconspicuous. Branch complements with one branch proximally
and 3?7 branches apically, branches 0.5?1 m long, slender, subequal. Culm sheaths
persistent, 1/2 as long as internodes, densely white pubescent, glabrescent, margins
densely white ciliate; auricles falcate, amplexicaul; oral setae many, radiate, ca. 1 cm;
ligule short, apex densely white fimbriate; blade reflexed, green, ovate-lanceolate.
Foliage leaves 2?5 per ultimate branch; sheaths glabrous, glossy, margins ciliate; auricles
present; oral setae deciduous, radiate, 5?7 mm; ligule short, apex long, white ciliate;
blade 7?20 ? 1.2?3 cm, thinly leathery, abaxially slightly glaucous, glabrous on both
surfaces, secondary veins indistinct, 4?7 pairs. Inflorescence imperfectly known,
semelauctant, racemose possibly with 1 or few spikelets; glumes not seen; florets 5; lemma
ca. 1 cm long, purple green; palea ca. 0.8 cm long; lodicules not seen; stamens 3,
anthers purple, 4 mm long; ovary and style not seen; stigmas 2, plumose.
Etymology. Hsuehochloa was named in honour of the late Prof. Chi-Ju Hsueh
(JiRu Xue in Pinyin transliteration) (1921?1999), a pioneer Chinese botanist on
bamboos of SW China and mentor of the senior author in 1983?1986. Hsueh stands for
his family name and chloa means grass.
Distribution and habitat. Endemic to south Guizhou, China, under broadleaved
forests in a limestone montane area at 500?950 m altitude.
Additional specimens examined. CHINA. Guizhou: Libo, 950 m alt., May 1982,
X. H. Song 919 (NF), J. P. Ruan 90041 (N), 600?700 m alt., November 6 2006, T. P.
Yi 06093 & 06094 (SIFS), 679 m alt., 25?26.691'N, 107?56.823'E, 14 April 2010, P.
F. Ma & Z. M. Cai 10050 (KUN), 653 m alt., 25?25.783'N, 107?56.533'E, 28 March
2015, C. Guo & Y. Guo GC 82 (KUN), 667 m alt., 25?25.7'N, 107?56.25'E, 16 May
2015, X. Y. Ye & M. Y. Zhou YXY190 (KUN).Yunnan (Kunming): cultivated in the
greenhouse of GBOWS, Kunming, 1900 m alt., January 2013, P. F. Ma s.n. (KUN).
We are grateful to curators of herbaria of Kunming Institute of Botany, Chinese
Academy of Sciences (KUN), Nanjing Forestry University (NF) and Sichuan
Agricultural University, Dujiangyan Campus (SIFS) for their help in specimen examination.
Thanks also go to Mr Zhao-Ming Cai, Ms Cen Guo and Ms Ying Guo of Kunming
Institute of Botany (KIB), Chinese Academy of Sciences for introducing the plants to the
greenhouse, to Ms Yang Yang of KIB and Dr Jie Zeng of Southwest Forestry University
for assistance in photographing. We also thank Dr Maria S. Vorontsova of Royal
Botanic Gardens Kew and two anonymous reviewers for their constructive suggestions.
This study was funded by the National Natural Science Foundation of China (Grants
31430011 and 31760049) and facilitated by the Germplasm Bank of Wild Species.
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