NIU Zheng-yang，TONG Yi-hua，NI Jing-bo，ZHANG Zhi-xian，XIA Nian-he

（1.Key Laboratory of Plant Resources Conservation and Utilization，South China Botanical Garden，Chinese Academy of Sciences，Guangzhou 510650，Guangdong，China；2.Core Botanical Gardens，Chinese Academy of Sciences，Guangzhou 510650，Guangdong，China；3.University of Chinese Academy of Sciences，Beijing 100049，China）

Abstract Dendrocalamus pulverulentoides N.H.Xia，J.B.Ni，Y.H.Tong＆Z.Y.Niu，a new species from Danxia Mountain，Guangdong，China，is described and illustrated.The new species is morphologically similar to D．latiflorus，D．minor and D．pulverulentus，but differs in having a ring of brown sericeous hairs at the infranodal to intranodal regions，culm leaf sheaths with dense appressed brown setae at the middle and lower parts of the abaxial surface and several yellowish white vertical stripes near the margins，ca 2 mm tall culm sheath ligules with a concave and serrulate margin，and 7－16 foliage leaves per ultimate branch with broadly triangular auricles and 1－5 mm long oral setae.

Key words New species；Dendrocalamus；Danxia Mountain

Introduction

DendrocalamusNees von Esenbeck［1］is one of the largest genera belonging to subtribe Bambusinae of tribe Bambuseae（Poaceae，Bambusoideae）［2］，with over 70 species distributed mainly in the tropical and subtropical regions of Asia［3－7］.In China，more than 30 species in this genus have so far been reported，with most distributed in Southwest China，especially Yunnan Province［7－10］.Six species of this genus are recorded in Guangdong Province，viz.D．latiflorusMunro，D．minor（McClure）L.C.Chia＆H.L.Fung，D．pulverulentusL.C.Chia＆But，D．stenoauritus（W.T.Lin）N.H.Xia，D．suberosus（W.T.Lin＆Z.M.Wu）N.H.Xia andD．triramus（W.T.Lin＆Z.M.Wu）N.H.Xia［4，11］.Dendrocalamusis a typical arborescent woody bamboo genus and can be characterized by its unicaespitose habit，pachymorph rhizomes，culms with pendulous apices，several branches at each node，reflexed culm sheath blades，large foliage leaves，clustered pseudospikelets with singlekeeled prophylls and six stamens［3－4，12－13］.In terms of economic value，the bamboos of this genus are often cultivated in villages for food，constructional materials and ornamental purposes［14－15］.

Danxia Mountain is one of the most famous scenic spots in Guangdong Province，China.It has a high plant diversity as well as an unique Danxia landform.A number of endemic new species from different plant families have been reported from this area recently，such asDryopterisshiakeanaH.Shang＆Y.H.Yan，Semiaquilegia danxiashanensisL.Wu，J.J.Zhou，Q.Zhang＆W.S.Deng andViolahybanthoidesW.B.Liao＆Q.Fan［16－18］..Moreover，an endemic new bamboo，PhyllostachysdanxiashanensisN.H.Xia＆X.R.Zheng，has also been discovered in Danxia Mountain［19］as recently as in 2019.

During a bamboo survey in Danxia Mountain National Nature Reserve，Renhua County，Guangdong，China in September 2020，we collected some specimens of an unknown bamboo.This species has the typical features ofDendrocalamus，such as an arborescent unicaespitose habit，pachymorph rhizomes，culms with pendulous apexes，several branches at each node，reflexed culm sheath blades and large foliage leaves，but after careful comparison with those species which seem to be closely related to it，it was found that none of previously described species inDendrocalamusmatch this bamboo taxon.Therefore，we concluded that it is a species new to science，which is described and illustrated below.

Materials and methods

Observations and measurements of the main morphological characters of the unknown species were carried out in the field on 25 September 2020.Some detailed characters，such as indumentum and ligule serration，were observed by stereomicroscope（Mshot MZ101）in the laboratory.Morphological characters of three related species（Dendrocalamuslatiflorus，D．minorandD．pulverulentus）were obtained based on related literature［4，20－22］，living plants cultivated in bamboo garden of the South China Botanical Garden and specimens deposited at IBSC.

Taxonomy

DendrocalamuspulverulentoidesN.H.Xia，J.B.Ni，Y.H.Tong＆Z.Y.Niu sp.nov.（Figs.1－2）

Fig.1 Dendrocalamuspulverulentoides N.H.Xia，J.B.Ni，Y.H.Tong＆Z.Y.Niu.A.Clump habit；B.Mature culms with culm sheaths；C.Culm sheath，detached；D.Basal branches of the culm；E.Culm sheath ligule，detail；F.Culm sheath blade.Photos A－D by Z.X.Zhang and E－F by Z.Y.Niu.

Fig.2 Dendrocalamuspulverulentoides N.H.Xia，J.B.Ni，Y.H.Tong＆Z.Y.Niu.A.Bud at culm node；B－C.Foliage leaves on ultimate branches，adaxial（B）and abaxial（C）views；D－E.Foliage leaf ligule；F－G.Foliage leaf auriclesand oral setae.Photos A－D＆F by Z.X.Zhang and E＆G by Z.Y.Niu.

Diagnosis：Dendrocalamuspulverulentoidesis morphologically similar toD．pulverulentusandD．minor，but differs from them in having a ring of brown sericeous hairs at the infranodal to intranodal regions，culm leaf sheaths with dense appressed brown setae abaxially at the middle and lower parts and several yellowish white vertical stripes near the margins，ca 2 mm tall culm sheath ligules with a concave and serrulate apex，and 7－16 foliage leaves per ultimate branch with broadly triangular auricles and 1－5 mm long oral setae.

Type：CHINA.Guangdong：Shaoguan City，Renhua County，Danxia Mountain National Nature Reserve，near Chewan Village，25°1′52″N，113°42′33″E，66 m alt.，25 September 2020，J.B.Nietal．DXS025（holotype：IBSC?。?

Description：Arborescent bamboo，rhizomes pachymorph，short-necked.Culms erect，8－10 m tall and ca 8 cm in diameter，apexes pendulous；internodes terete，25－35 cm long，initially covered with thick white powder，glabrous；both the infranodal and intranodal regions covered with a 5 mm wide band of brown sericeous hairs；culm wall ca 1 cm thick；nodes conspicuous；sheath scars prominent，with persistent remains of sheath base.Primary branch buds broadly ovate，not sunken into culm internode surface.Branches several at each node，the central one dominant；branches developing from10th to 13th nodes upwards，ca 4 m above ground，inclined at an angle of 45°－60°with the culm.Culm sheaths caducous，thickly leathery，apex concave，initially yellowish green，brown when dry，22.5－28.5×29.5－45 cm，abaxial surface with the middle and lower parts densely appressed brown setose and thinly white powdery，with several yellowish white vertical stripes near the margins，stripes inconspicuous when dry；margins deciduously white ciliate；oral setae 1－5 mm long；auricles narrowly elliptic，ca 2 mm long and 0.5 mm wide；ligules ca 2 mm tall，serrulate，apex concave，densely ciliate，ciliae fragile，easily broken off，serrations with ciliolate margins；blades reflexed，ovate-lanceolate，usually sinuous，3－6.5×1－1.5 cm，ca 1／5 as long as sheath proper，base 1／2－2／3 as wide as sheath apex，middle and upper parts involute，adaxially brown hispid at base，abaxially glabrous.Foliage leaves7－16 per ultimate branch；sheaths6－16 cm long，initially sparsely setose，glabrescent，margin glabrous；auricles broadly triangular，caducous；oral setae 1－5 mm long；ligules ca 1 mm tall，apex arched，serrulate，abaxially white puberulent；petioles 3－8×2－4 mm，glabrous；leaf blades lanceolate，papyraceous，14－45×（1.3－）4.5－8.5 cm，apex acute，base widely cuneate or truncate，both sides glabrous，secondary veins 6－14 pairs，transverse veins inconspicuous.Inflorescence unknown.

Phenology：Culm shoots produced during July to September.

Distribution and habitat：This new species is only found in the type locality，i.e.，Danxia Mountain，Renhua County，Guangdong，China.It is cultivated near villages at an altitude of ca 75 m.No wild population was discovered.

Etymology：The specific epithet refers to the similarity between this new species and the closest related speciesDendrocalamuspulverulentusL.C.Chia＆But.

Local uses：Young culm shoots are edible for local people and not bitter，and the clumps have ornamental value.

Chinese vernacular names：xiǎo mázhú（小麻竹），mázhúzǎi（麻竹仔）.

Discussion

This new species resemblesD．pulverulentus，D．minorandD．latiflorus，but can be easily distinguished from the three related species by several morphological characters shown in Table 1.Specifically，it can be distinguished fromD．pulverulentusby having culm sheaths with a length-width ratio of 1／2－5／6（vs.7／6－5／4），middle and lower parts（vs.entire）of culm sheaths with dense brown setae，ca 2 mm tall（vs.ca 4 mm）culm sheath ligules with a concave apex（vs.convex），and 7－16 foliage leaves per ultimate branch（vs.5－7）with broadly triangular auricles and 1－5 mm long oral setae（vs.auricles and oral setae absent）.It differs fromD．minorin having ca 10 mm thick culm wall（vs.5－5.6 mm），culm sheaths with a length-width ratio of 1／2－5／6（vs.3／4－11／10）and several yellowish white stripes near margins（vs.stripes absent），ca 2 mm tall culm sheath ligules with a serrulate and concave apex and 0.5－1 mm long ciliae（vs.3－8 mm tall culm sheaths with an entire and convex apex and 6－8 mm long fimbriae），base of culm sheath blades 1／2－2／3 as wide as sheath apex（vs.2／5－1／2），and 7－16 foliage leaves per ultimate branch（vs.3－8）with broadly triangular auricles and 1－5 mm long oral setae（vs.auricles and oral setae absent）.It can be distinguished fromD．latiflorusby having 8－10 m tall culms（vs.20－25 m）with an diameter of 8 mm（vs.15－30 mm），densely brown sericeous infranodes（vs.glabrous），culm sheaths abaxilly with dense brown setae on middle and lower parts（vs.only base）and several yellowish white stripes near margins（vs.stripes absent）and foliage leaves with broadly triangular auricles and 1 5 mm long oral setae（vs.auricles and oral setae absent）.An identification key to the four species is provided below.

Tab.1 Morphological comparison of Dendrocalamus pulverulentoides and related species

Key toDendrocalamuspulverulentoidesand three related species.

1.Culm 20 25 m tall；only culm sheath bases densely appressed brown setose，glabrescent……D．latiflorus

1.Culm 6－12 m tall；middle and lower parts of culm sheaths or entire culm sheaths densely appressed brown setose，trichomes persistent………………………………………………………………………2

2.Culm sheath ligules apex entire，with dense 6－8 mm long fimbriae；culm sheaths without stripes……………………………………………………………………………………………………D．minor

2.Culm sheath ligules apex serrulate，with dense 0.5－1 mm long ciliae；culm sheaths with yellowish white stripes abaxially……………………………………………………………………………………3

3.Culm sheath ligule apex convex；foliage leaf auricles and oral setae absent；foliage leaves 5－7 per ultimate branch…………………………………………………………………………D．pulverulentus

3.Culm sheath ligule apex concave；foliage leaf auricles broadly triangular，oral setae 1－5 mm long；foliage leaves 7－16 per ultimate branch…………………………………………………D．pulverulentoides

Acknowledgements

This study was supported by the National Natural Science Foundation of China（grant no.31670196），and the Project“Investigation of Bamboo Plants in Danxia Mountain Nature Reserve”.We also appreciate the staff of Danxiashan Nature Reserve for their help during field trips.