SYSTEMATICS Botanical Studies (2010) 51: 107-117. Begonia ×breviscapa (Begoniaceae), a new intersectional natural hybrid from limestone areas in Guangxi, China Ching-IPENG1,YanLIU2,Shin-MingKU1,YoshikoKONO1,andKuo-FangCHUNG3,* 1 Herbarium (HAST), Biodiversity Research Center, Academia Sinica, Nangang, Taipei 115, Taiwan Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences, Guilin 541006, P.R. China 3 School of Forestry and Resource Conservation, National Taiwan University, Daan, Taipei 106, Taiwan 2 (ReceivedNovember13,2008;AcceptedOctober30,2009) ABSTRACT.Anewnaturalhybrid,Begonia ×breviscapaC.-IPeng,YanLiu&S.M.Ku,fromnorthwestern Guangxi, China, is described and illustrated.A somatic chromosome number of 2n = 30 was determined. Based on morphological features, geographical range, pollen stainability and seed set we conclude that B. ×breviscapaisanaturalhybridbetweenB. variifoliaY.M.Shui&W.H.Chen[sect.CoelocentrumIrmsch.] and B. leprosa Hance [sect. Leprosae (T. C. Ku)Y. M. Shui]. This is the first documentation of natural hybridizationbetweenbegoniasoftwodifferentsectionsinmainlandChina. Keywords:Begonia ×breviscapa;Begonia leprosa;Begonia setulosopeltata;Begonia variifolia;Begoniaceae; China; Chromosome number; Guangxi; Limestone lora; Natural hybrid. INTRODUCTION MATERIALS AND METHODS Inrecentyearsmanybotanicalnoveltieswerereported from limestone areas in southern China and northern Vietnam,e.g.,Acanthaceae(Chenetal.,2009),Asteraceae (Zhang et al., 2008), Balsaminaceae (Yu et al., 2009), Begoniaceae (Fang et al., 2006; Ku et al., 2006, 2008; Liu et al., 2005, 2007; Peng et al., 2006, 2007, 2008a,b; Shui and Chen, 2005), Berberidaceae (Wu et al., 2009), Gesneriaceae(Wenetal.,2009),Ranunculaceae(Yuanand Yang, 2009), Rubiaceae (Wang et al., 2010), Ruscaceae (Houetal.,2009)andferns(Wangetal.,2010;Zhangand He, 2009a,b; Zhang et al., 2010), to name a few. During our survey of limestone caves in Guangxi, China, we discovered a Begonia that was neither identiiable to any of the species reported in the Flora of China (Gu et al., 2007)nortoanycongenersthatwerepublishedthereafter. Based on detailed comparisons of salient morphological and anatomical features, geographical range, pollen stainability and seed set, we concluded that it represents a new intersectional natural hybrid, which we name Begonia ×breviscapaC.-IPeng,YanLiu&S.M.Ku.Its putativeparentsareB. variifoliaY.M.Shui&W.H.Chen [sect. Coelocentrum Irmsch.] and B. leprosa Hance [sect. Leprosae(T.C.Ku)Y.M.Shui]. Cryo scanning electron microscopy Fresh leaves of Begonia ×breviscapa, B. variifolia Y. M. Shui & W. H. Chen, B. leprosa Hance and B. setulosopeltata C.Y. Wu were dissected and attached to a stub. The samples were frozen with liquid nitrogen slush,thentransferredtoasamplepreparationchamberat -160°C.After5min,whenthetemperatureroseto-130°C, the samples were fractured.The samples were etched for 10 min at -85°C.After coating at -130°C, the samples were transferred to the SEM chamber and observed at -160°C with a cryo scanning electron microscope (FEI Quanta200SEM/QuorumCryo SystemPP2000TRFEI). Voucher specimens (Begonia ×breviscapa: Peng et al. 20727; B. leprosa: Peng et al. 18737; B. setulosopeltata: Peng et al. 19830; B. variifolia: Peng et al. 20729) have beendepositedatHAST. *Correspondingauthor:E-mail:kuofangchung@ntu.edu.tw. Chromosome preparations Root tips of Begonia ×breviscapa were pretreated with 2 mM 8-hydroxyquinoline solution at 15-18°C for about 8 h and fixed in ethanol-acetic acid (3:1) below 4°C for over 24 h. Chromosome preparations were made by the enzyme squash method in an enzyme mixture of 4% Cellulase Onozuka R10 (Yakult Honsha, Tokyo, Japan) and 2% Pectolyase (Sigma, St. Louis, MO, USA) Botanical Studies, Vol. 51, 2010 108 atabout37°Cfor1h.Thepreparationswerestainedwith a 2% Giemsa solution (Merck, Darmstadt, Germany). Classiication of the chromosome complements based on centromere position at mitotic metaphase follows Levan etal.(1964).Avoucherspecimen(Peng et al.20727) has beendepositedinHAST. NEW HYBRID Begonia ×breviscapa C.-I Peng,Yan Liu & S. M. Ku, hybr. nov. —TYPE: CHINA. Guangxi Zhuangzu Autonomous Region, Donglan Xian (County), Sanshi Zhen, Naying Village, on the way to Wuzhuan, SEfacing limestone cave, elev. ca. 320 m. Plants sterile Figure 1. Begonia ×breviscapa.A, Habit; B, Portion of leaf margin, adaxial surface, B’, abaxial surface; C, Stipule; D, Staminate lower, face view, D’ , back view; E, Androecium; F, Stamen, abaxial view, F’, adaxial view, F’’, lateral view; G, Carpellate lower, faceview,G’,backview;H,Stylesandstigmas,H’abaxialview,H’’,adaxialview;I,Undevelopedfruit;J,Serialcrosssectionsof undevelopedfruit.[AllfromC.-I Peng et al. 20727(HAST)] PENG et al. — Begonia ×breviscapa in Guangxi, China 109 Figure 2. Begonia ×breviscapa.A,Habitat,co-occurringwithB. variifoliaonlimestonerockincave;B,Habit;C,D,Leaf,adaxial surface; E, Leaf, abaxial surface; F, Stipule; G, Inlorescence; H, Staminate lower; I, Carpellate lower, face view; J, Carpellate lower, sideview;K,Undevelopedfruit;L,Middlecrosssectionofovary,viewedunderdissectingmicroscope;M,Middlecrosssectionof ovary,viewedunderlightmicroscope.[C.-I Peng et al. 20727(HAST)] 110 when collected on 18 Dec 2005. Flowering specimens pressedon11May2008fromplantsbroughtbackfor cultivation,Ching-I Penget al. 20727a(holotype:IBK; isotype:HAST)短葶秋海棠Figures1,2 Begonia ×breviscapa aspectu similis Begoniae s e t u l o s o p e l t a t a e , s e d i n f l o re s c e n t i i s b re v i b u s pubescentibus, pollinis granis et ovariis abortivis; hybrida naturalis e B. variifolia et B. leprosa. Herbs,monoecious.Rhizomecreeping,6-13mmthick, internodes5-11mmlong,pilose.Stipulescaducous,ovatetriangular, asymmetric, 7-24 mm long, 6-14 mm wide, weakly keeled, margin entire, apex aristate, arista hairlike.Leavesalternate;petiole9-26cmlong,3-5mmthick, villous (hairs 2-4.5 mm long); blade obliquely broadly ovate, peltate or subpeltate, sometimes basifixed with cordate base, 8-15 (-23) cm long, 6-11 (-16) cm wide, papery, adaxially with white spots all over, moderately setulose (trichomes 0.5-1 mm long), abaxially brownishreddish or green, pilose on veins (trichomes whitish, 0.5-1.2 mm long), margin shallowly unequally minutely serrulate or crenate, apex acute, mucronate, cuspidate, or shortly acuminate; venation basally 7-8-palmate, tertiary veins loosely reticulate or pinnate-reticulate. Inflorescences axillary; peduncle (scape) 1.5-5 cm long, pilose or villous-pilose; flowers 5-8 in dichasial cymes; bracts caducous, ovate or oblong, 3-6 mm long, 3-5 mm wide, margin serrate-ciliate, apex obtuse. Staminate lower: pedicels 1.5-3 cm, pilose; tepals 4, white, outer 2 broadly obovate, 0.9-1.5 cm long, 0.9-1.3 cm wide, base broadly cuneate or subrounded, apex rounded, outside pilose, inner 2 elliptic to oblanceolate, 8-10 mm long, 3.5-5 mm wide, apex obtuse; stamens 30-40; filaments ca. 1.5-2.8 mm long; anthers obovate-oblong, 0.8-1.1 mm; apex of connective  ± emarginate. Pollen grains irregular, shriveled and unstainable. Carpellate flowers: pedicel1.3-1.7cm,piloseorsparselyso;tepals3,outer2 suborbicularorbroadlyobovate,1.3-1.7cmlong,1.3-1.6 cmwide,basebroadlycuneateorrounded,apexrounded, inner 1 oblanceolate or elliptic, 10-15 mm long, 5-6 mm wide; ovary trigonous-ellipsoid, 9-13 mm long, 4-5 mm across,piloseorsparselyso,subequallyweakly3-winged; placentationparietalinupperhalf,axileinlowerhalf,each placenta with 2 lamellae; styles 3, ca. 7 mm long, nearly free, stigma spirally twisted, papillose all around. Fruits not seen. Somatic chromosome number, 2n = 30 (Figure 3). Additional specimen examined. CHINA. Guangxi ZhuangzuAutonomous Region, Donglan Xian (County), Sanshi Zhen, Naying Village, on the way to Wuzhuan, SE-facing limestone cave, elev. ca. 320 m, 18 Dec 2005, Ching-I Penget al. 20727(originalsterilecollectionofthe typematerial;HAST). Phenology. Flowering from February to May in cultivation. Distribution. Donglan Xian, northwestern Guangxi, China (Figure 4). Begonia ×breviscapa was found inside alimestonecaveonthesamerockfacewithB. variifolia, Botanical Studies, Vol. 51, 2010 Figure 3. Somatic chromosomes at metaphase of Begonia ×breviscapa (2n = 30), arrows indicating a pair of long, metacentricchromosomes(FromC.-I Peng et al.20727,HAST). Figure 4. DistributionofBegonia ×breviscapa(★),B. variifolia (○), B. setulosopeltata (▲), and B. leprosa (shaded area) in GuangxiZhuangzuAutonomousRegion,China. Figure 5. Microphotograph of abortive pollens of Begonia ×breviscapa.[FromC.-I Peng et al.20727,HAST] PENG et al. — Begonia ×breviscapa in Guangxi, China 111 Figure 6. Begonia variifolia Y.M.Shui&W.H.Chen.A,B,Habitandhabitat;C,Habit;D,Leaf,abaxialsurface,greenform;E,Leaf, abaxial surface, red form; F, Staminate lower; G, Carpellate lower, side view; H, Carpellate lower, face view; I, J, Fruits. [A from C.-I Penget al.21063 (HAST);B,C,E,JfromC.-I Peng et al. 20734 (HAST);D,F-IfromC.-I Peng et al. 20728 (HAST)] 112 Botanical Studies, Vol. 51, 2010 Figure 7. Begonia leprosa Hance.A, Habit; B, Inflorescence; C, Staminate flower with larger, pink tepals and zygomorphic androecium; D, Staminate lower with smaller, white tepals and actinomorphic androecium; E, Carpellate lower, face view; F, G, Fruits;H,Middlecrosssectionofayoungfruit.[A,GfromS.M. Ku et al. 2074 (HAST);BfromC.-I Peng etal.20333 (HAST);C fromW.C. Leong et al. 3416 (HAST);FfromC.-I Peng et al. 19474;HfromC.-I Peng et al. 18737 (HAST)] PENG et al. — Begonia ×breviscapa in Guangxi, China 113 Figure 8. Begonia setulosopeltata C.Y. Wu.A, Habit and habitat; B, Habit; C, Leaf, abaxial surface; D, Stipule; E,A developing inlorescence with a pair of bracts at base; F, Inlorescence; G, Staminate lower; H, Carpellate lower, face view; I, Carpellate lower, sideview;J,Stylesandstigmas;K,Middlecrosssectionofovary;L,Fruit.[AllfromC.-I Peng et al. 19830 (HAST)] Botanical Studies, Vol. 51, 2010 114 oneoftheputativeparents(Figure2A).Begonia leprosa, theotherputativeparent,wasgrowingonthesunlitrocky entrance of the cave. Begonia asteropyrifolia was also nearby.ItisrareforseveralspeciesofBegoniatoco-occur inthisway. Etymology. The speciic epithet refers to the shortness ofthescape. Chromosome cytology.  Somatic chromosomes at mitotic metaphase of Begonia ×breviscapa were determined to be 2n = 30 (Figure 3). The chromosome Table 1.ComparisonofBegonia ×breviscapa,B. setulosopeltata,B. variifolia,andB. leprosa Begonia×breviscapa (Figures1,2) Begonia variifolia (Figure6; Kuetal.,2008:Figure3B) Begonia leprosa (Figure7) Begonia setulosopeltata (Figure8) Leafblade Size(cm) 7-24×6-14 5-10×3.5-7.2 4.5-21×4-17 7-14.6×4.5-10 Base Peltateorsubpeltate, sometimes basiixed withcordatebase Peltateorsubpeltate, sometimes basiixed with cordatebase Basiixed, shallowly todeeplycordate Peltate Indumentum Adaxiallymoderately setulose;abaxially piloseonveins Adaxiallyvillous-setulose; abaxiallyvillose-pilose, particularlypronouncedon veins Adaxiallywithfew short-setosehairs; abaxiallypiloseor villose-hirsuteon majorveins Adaxiallysparingly hispidulousorsetulose; abaxiallysparingly hirsuteonmajorveins Maculationon Withwhitespotsall adaxialsurface over Withorwithoutawhiteband Lacking alongmidrib,palegreen alongmajorveinsand majorlateralveins;green orbrownishbetweenmajor veins Withwhitespotsallover Tertiaryvenation Looselyreticulate,veins Reticulateandpercurrent,veins Usuallynotreticulate, Reticulate,veinsatacute veinsatacuteangles atacuteobliqueangles atperpendicularorobtuse angles angles Upperepidermal 40-80 μm across, protuberant;smooth cells (Figure9A) Crosssection 250-280 μm thick; epidermis1-layered (Figure9B) StomatalcomplexElevated;singular (Figure9B,C) 80-140 μm across; conical and 38-80 μm across; 45-80 μm across, sub-papillate;smooth(Figure nearly lat to protuberant;smooth slightlyprotuberant; (Figure9J) 9D) scaberulous(Figure 9G) 240-260 μm thick; epidermis 1-layered(Figure9E) 500-600 μm thick; epidermis2-layered (Figure9H) 220-230 μm thick; epidermis1-layered (Figure9K) Elevated;singular(Figure9F) Nearly lat; in groups of2or3(Figure9I) Nearly lat; singular (Figure9L) 7.5-21 14-20.5 Scape length(cm) 1.5-5 Indumentum Piloseorvillous-pilose Piloseorvillous Glabrousorpuberulent Glabrous Pedicel Pilose Pilose Minutelypuberulent Glabrous Outerstaminate tepals(mm) 9-15×9-13 11-16×12-18 7-27×8-21 12-17×10-16 Outercarpellate tepals(mm) 13-17×13-16 9-16×9-15 5.5-17×6-13 14-21×18-21 Indumentum Pilose Villous Minutelypuberulent Glabrous Wings Weakly3-winged 3-winged Lacking 3-winged Placentation Parietalinupperhalf, axileinlowerhalf Parietal Axile Parietal (0.3-)1-1.5(-7) Ovary PENG et al. — Begonia ×breviscapa in Guangxi, China 115 Figure 9. Cryo SEM microphotographs of Begonia leaves.A-C, Begonia ×breviscapa; D-F, B. variifolia; G-I, B. leprosa; J-L, B. setulosopeltata.A,D,G,J,Adaxialepidermis;B,E,H,K,Leafcrosssection;C,F,I,L,Abaxialepidermis.(A-CfromC.-I Peng et al. 20727;D-FfromC.-I Peng et al. 20729;G-IfromC.-I Peng et al. 18737;J-L fromC.-I Peng et al. 19830) 116 complement showed bimodal variation in length.Among the 30 chromosomes, two were longer, about 1.9-2.1 µm long(Figure3:arrows),andtheremaining28wereshorter, about0.8-1.2µmlong.Thepositionofthecentromereof someoftheshorterchromosomescouldnotbedetermined. The two longest chromosomes, however, were clearly metacentric. Satellites were not observed. The somatic chromosome number of all 17 taxa of Begonia in sect. Coelocentrumthatareknownis,withoutexception,2n = 30(Fangetal.,2006;Kuetal.,2004,2006,2008;Liuet al.,2005;Pengetal.,2005a,2005b,2007,2008a,2008b). Among them, four taxa, namely B. ningmingensis var. bella,B. kui,B. pengiiandB. arachnoidea,haveabimodal karyotype with two long, metacentric chromosomes and 28shortchromosomes(Fangetal.,2006;Kuetal.,2008; Pengetal.,2007,2008b). Notes. Basedonacomparisonofsalientmorphological features (Table 1) and pollen stainability (Figure 5), we conclude that the unusual plant from Donglan Xian (County) represents natural hybrids between B. variifolia Y.M.Shui&W.H.Chen(Figure6)andB. leprosa Hance (Figure7)thatco-occurwithitinthesamelimestonecave. Begonia leprosabelongstothesmallsectionLeprosaethat comprises four species, three in southern China (Shui et al.,2002)andoneinVietnam(Tametal.,2005).Section Leprosae is characterized by having peculiar pendulous, sausage-shaped, indehiscent fruits. Hybrids involving B. leprosahadnotbeendocumentedatthetimeTebbit(2005) published his book ‘Begonias: Cultivation, Identiication, andNaturalHistory.’ B e g o n i a × b re v i s c a p a a l s o b e a r s a s u p e r f i c i a l resemblance to B. setulosopeltata C.Y. Wu (Figure 8) in aspect, differing markedly in the short peduncle and pubescent inflorescences.A detailed comparison of the fourspeciesisprovidedinTable1.ItisnoteworthythatB. ×breviscapahasuniqueunicellular(globose)orbicellular (globose-headed) hairs on the abaxial leaf epidermis (Figure 9C). Such hairs are known only in few species in Begonia sect. Coelocentrum, such as in B. variifolia (oneoftheputativeparents;Figure9F),B. pengii (Kuet al., 2008: Figure 6E) and B. asteropyrifolia (unpublished data), suggesting their close afinities. Acknowledgments.WethankDavidE.Boufford(A/GH), QinerYang (IBSC) and Thomas G. Lammers (OSH) for improving the manuscript; QinerYang (IBSC) for providingtheLatindiagnosis;andMing-ChaoYu(HAST) forthelinedrawings.Thisstudywassupportedinpartby funding from the Personnel Training Plan of West Light Foundation of the ChineseAcademy of Sciences (2007) toYanLiuandNationalScienceCouncil,Taiwanandthe NationalGeographicSociety(Grant#8358-07;Botanical Exploration of Limestone Karsts of Southern Guangxi, China)toChing-IPeng. Botanical Studies, Vol. 51, 2010 LITERATURE CITED Chen,W.H.,Y.M.Shui,Y.K.Sima,R.M.Zhang,andZ.D.Wei. 2009.Pararuelliaglomerata(Acanthaceae),anewspecies fromYunnan,China.Bot.Stud.50:261-267. Fang, D., S.M. Ku,Y.G. Wei, D.H. Qin, and C.-I Peng. 2006. Three new taxa of Begonia (sect. Coelocentrum, Begoniaceae) from limestone areas in Guangxi, China. Bot. Stud. 47:97-110. Gu, C.Z., C.-I Peng, and N.J. Turland. 2007. Begoniaceae. In Z.Y.Wu,P.H.Raven,andD.Y.Hong(eds.),FloraofChina, Vol.13.SciencePress,BeijingandMissouriBotanicalGardenPress,St.Louis,pp.153-207. 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Liu, and Q.E. Yang. 2008. Sinosenecio jishouensis (Compositae), a new species from north-west Hunan,China.Bot.Stud.49:287-294. 中國廣西石灰岩地區秋海棠屬新組間雜交種：短葶秋海棠 彭鏡毅1 劉演2 古訓銘1 河野淑子1 鍾國芳3 1 中央研究院 生物多樣性研究中心植物標本館 (HAST) 2 廣西壯族自治區中國科學院 廣西植物研究所 3 國立台灣大學 森林環境暨資源學系 本文報導中國廣西壯族自治區石灰岩地區秋海棠屬一新雜交種 ： 短葶秋海棠 ( B e g o n i a ×breviscapa)，提供線繪圖與彩色照片以資辨識，並報導其染色體數目 (2n = 30)。由於該植物與數種 秋海棠屬植物共域分布，且花粉可染性極低，人工授粉後不著果，經觀察比較其形態特徵後我們推斷 其為生長在同一石灰岩洞穴的側膜組 (sect. Coelocentrum) 之多變秋海棠 (B. variifolia) 與棒果組 (sect. Leprosae) 的癩葉秋海棠 (B. leprosa) 之天然雜交種。此為中國大陸秋海棠屬組間天然雜交之首次報導。 關鍵詞 ： 短 葶 秋 海 棠 ； 癩 葉 秋 海 棠 ； 刺 盾 葉 秋 海 棠 ； 多 變 秋 海 棠 ； 秋 海 棠 科 ； 中 國 ； 染色體數 ； 廣西 ； 石灰岩植物 ； 天然雜交。