Botanical Studies (2012) 53: 283-290.
SYSTEMATICS
Begonia chongzuoensis (sect. Coelocentrum,
Begoniaceae), a new calciphile from Guangxi, China
Ching-I PENG1, Shin-Ming KU1, Yoshiko KONO1, and Yan LIU2 *
1Herbarium (HAST), Biodiversity Research Center, Academia Sinica, Nangang, Taipei 115, Taiwan
2Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences, Guilin 541006, China
(Received February 2, 2012; Accepted March 6, 2012)
ABSTRACT. Begonia chongzuoensis Yan Liu, S. M. Ku & C.-I Peng (sect. Coelocentrum), a new species from Guangxi Zhuangzu Autonomous Region, China, is here described and illustrated. A somatic chromosome number of 2n = 30 was determined. Begonia chongzuoensis somewhat resembles B. obliquifolia S. H. Huang & Y. M. Shui, from which it differs by the moderately to sparsely setulose leaf surface; glabrous inflorescences, flowers and fruits; and crescent-shaped abaxial wing of the fruit. The new species is known only from a limestone hill in western Guangxi.
Keywords: Begonia chongzuoensis; Begonia obliquifolia; Begonia sect. Coelocentrum; Begoniaceae; China; Chromosome number; Guangxi; Limestone flora; New species; Rare species.
INTRODUCTION
In continuation of our studies of Asian Begonia (e.g., Hughes et al., 2011; Ku et al., 2008; Liu et al., 2007; Nguyen et al., 2010; Peng and Ku, 2009; Peng et al., 2006a,b, 2007, 2008a,b, 2010), we report the discovery of another undescribed species, B. chongzuoensis Yan Liu, S. M. Ku & C.-I Peng (sect. Coelocentrum), from a karst limestone hill in Guangxi, China.
NEW SPECIES
Begonia chongzuoensis Yan Liu, S. M. Ku & C.-I
Peng, sp. nov. ―TYPE: CHINA. Guangxi Zhuangzu Autonomous Region, Chongzuo Shi, Jiangzhou Qu, Banli Xiang, Nongguanshan, elev. ca. 230 m, at base of limestone slope, in rock crevices with or without abundant leaf litter, shaded, moist, rare, associated with Iodes ovalis, Psychotria, Schefflera, Cleidion brevipetiolatum, Tetrastigma panicaule, Piper sarmentosum, Desmos chinensis, Asarum, Maesa japonica, Erythropalum scandens, 17 Mar 2005. Speci­mens pressed from cultivated plant on 23 Aug 2005, Ching-I Peng, Yan Liu, Shin-Ming Ku, Huan-Yu Chen 20390-A (holotype: IBK; isotype: HAST).崇左秋海棠
Figures 1, 2
Species description. Herbs, monoecious, epipetric, perennial, rhizomatous. Rhizome 6-15 cm or longer, (5-)7-10(-12) mm thick, internodes (3.5-)5-10(-12) mm
long, reddish brown, nearly glabrous. Stipules eventually caducous, ovate or triangular-ovate, 8-9 mm long, 6.5-8.5 mm wide, reddish hyaline, with red venation, herbaceous, weakly or not keeled, glabrous or with few hairs along midrib, margin eciliate or sparsely ciliolate, apex aristate, arista 2-3 mm long, hair-like. Leaves 2-7, alternate, simple, asymmetric, unlobed or very shallowly lobed, broadly ovate, base deeply cordate, margin crenate-denticulate and ciliate, apex acuminate or shortly so, (6-)7-11(-13) cm long (basal lobes included), (5-)6-8(-10) cm wide, usually dark brownish to purplish red between major veins and major lateral veins, texture papery, surface slightly rugose, adaxially moderately to sparsely setulose (trichomes 0.3-1 mm long, whitish-hyaline or reddish), abaxially pilose along veins; venation basally 6(-7)-palmate, midrib distinct, veins pinnate along midrib, with 1-2 major lateral veins on each side, other primary veins branching dichotomously or nearly so, tertiary veins reticulate and weakly percurrent, forming a divergence angle of 70-100° to major veins, minor veins reticulate, all veins on abaxial surface prominently raised; petiole terete, 4.5-15 cm long, 2-3.8 mm thick, brownish red, sparsely hirsute-villous. Inflorescences axillary, dichasial cymes, 1-3 or more, arising directly from rhizome, usually below the leaf blades, branched 2 to 3 times. Flowers 4-8 per inflorescence; staminate flowers 3-6, carpellate flowers 1-2; peduncle terete, erect or ascending, 5-12 cm long, 1-1.8 mm thick, reddish brown or greenish, glabrous. Bracts caducous, oblong, ovate or rounded, margin denticulate and ciliate, apex obtuse or rounded, 2-8 mm long, 1.8-6 mm wide, smaller on distal pairs. Staminate flowers: pedicel 1-1.3 cm long, glabrous or subglabrous; tepals 4, outer

*Corresponding author: E-mail: gxibly@163.com.
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Figure 1. Begonia chongzuoensis Yan Liu, S. M. Ku & C.-I Peng. A, Habit; B, Portion of leaf, adaxial surface showing margin and indumentum, B', abaxial surface; C, Stipule; D, Bracts; E, Staminate flower; F, Androecium; G, Stamens; H, Carpellate flower, face view; I, J, Style and stigmas; K, Cross section at middle of young fruit; L, Seed. All from C.-I Peng et al. 20390 (HAST).
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Figure 2. Begonia chongzuoensis Yan Liu, S. M. Ku & C.-I Peng. A, Habitat; B, Habit; C, Stipules, a: adaxial surface, b: abaxial sur­face; D, Staminate and carpellate flowers; E, Carpellate flower, face view; F, Carpellate flower, side view; G, Cross section at middle of young fruit; H, Fruit; I, Seed SEM microphotograph. All from C.-I Peng et al. 20390 (HAST).
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2 suborbicular, base rounded or slightly cordate, margin usually eciliate, sometimes remotely ciliate, apex rounded, 11-14.5 mm long, 11-15 mm wide, white or slightly pinkish, glabrous; inner 2 tepals obovate or narrowly so, base cuneate, margin eciliate, apex obtuse or rounded, 9-11 mm long, 3.5-5 mm wide, white, glabrous; androecium zygomorphic, subglobose, stamens 25-35, golf-club-shaped; filaments subequal, 1.2-3 mm long, nearly free; anthers ± ascending, 2-locular, slightly compressed, obovoid, connective apex emarginate, 1-1.5 mm long, 0.7-1 mm wide, yellow. Carpellate flowers: pedicel 6-7 mm long, horizontally spreading to pendent, bracteole absent; tepals 3, caducous, outer 2 tepals suborbicular or oblate-ovate, margin usually eciliate, 9.5-11.5 mm long, 10-11.5 mm wide, white or slightly pinkish, glabrous; inner tepal elliptic or broadly lanceolate, base cuneate, apex obtuse or acute, 6-8 mm long, 2.5-3 mm wide, white, glabrous; ovary trigonous-ellipsoid, slightly compressed, 5-6.5 mm long, 4.5-5.3 mm thick (wings excluded), glabrous, 3-winged; 1-locular with intruded parietal placentation (axile at base); placentae 3, each 2-branched and T-shaped; styles 3, nearly free, yellow, 2.8-3.5 mm long, apically C-shaped; stigmatic band spiraled. Capsule nodding, trigonous-ellipsoid, somewhat compressed, 7.5-10 mm long, 5-5.5 mm thick (wings excluded), apex with persistent styles; wings equal or subequal; lateral wings 2-2.5 mm tall; abaxial wing crescent-shaped or nearly so, 2.5-3 mm tall. Seeds numerous, brown, ellipsoid or ovoid-ellipsoid, 0.5­0.57 mm long, 0.29-0.32 mm thick, chalazal end rounded, micropylar end obtuse, outer periclinal walls of mature seeds concave; collar cells elongated, straight, nearly rectangular, 10-13 cells in a ring, occupying 1/4-1/2 of seed length. Somatic chromosome number, 2n = 30 (Figure 3).
Additional specimens examined. CHINA. Guangxi Zhuangzu Autonomous Region, Chongzuo Shi, Jiangzhou Qu, Banli Xiang, Nongguanshan, elev. ca. 230 m, at base of limestone slope, in rock crevices with or without abundant leaf litter, shaded, moist, rare, 17 Mar 2005, Ching-I Peng, Yan Liu, Shin-Ming Ku, Huan-Yu Chen 20390 (HAST, field collection of the type); Chongzuo Xian, Banli Xiang, White-headed Langur (Trachypithecus leucocephalus) Reserve, in sparse forests on limestone hill slope, elev. ca. 220 m, 25 Aug 2004, White-headed Langur Reserve Compl. Exped. B0564 (IBK).
Distribution and ecology. Known only from the type locality in southwestern Guangxi, China (Figure 4). Base of a steep limestone slope in an evergreen forest.
Etymology. The specific epithet is derived from the type locality, Chongzuo City.
Phenology. Flowering from May to Sep; fruiting from June to Oct.
MATERIALS AND METHODS
Chromosome preparations
Root tips of Begonia chongzuoensis were pretreated with 2 mM 8-hydroxyquinoline solution at 15-18°C
for about 8 h and fixed overnight in ethanol-acetic acid (3:1) below 4°C. 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) at 37°C for about 1 h. Chromosomes were stained with a 2% Giemsa solution (Merck, Darmstadt, Germany).
Figure 3. Somatic chromosomes at metaphase of Begonia chongzuoensis, 2n = 30 (from C.-I Peng et al. 20390-A). A, Microphotograph. Arrows indicate longer metacentric chromosomes in the complement; B, Somatic chromosomes serially arranged by length and position of centromeres. Scale bars = 2 (m.
Figure 4. Distribution of Begonia chongzuoensis (★) in Guangxi Zhuangzu Autonomous Region, China.
PENG et al. — Begonia chongzuoensis, a new calciphile from Guangxi, China
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Classification of the chromosome complement based on centromere position at mitotic metaphase follows Levan et al. (1964). A voucher specimen (Peng et al. 20390-A) has been deposited in HAST.
Cryo scanning electron microscopy
Fresh leaves of Begonia chongzuoensis Yan Liu, S. M. Ku & C.-I Peng and B. obliquifolia S. H. Huang & Y. M. Shui were dissected and attached to a stub. The samples
Figure 5. Begonia leaf SEM microphotographs. A-C, Begonia chongzuoensis; D-F, B. obliquifolia; A, D, Trichomes on upper epidermis; B, E, Lamina, cross section; C, F, Trichomes on lower epidermis.
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were frozen with liquid nitrogen slush, then transferred to a The samples were etched for 10 min at -85°C. After coating sample preparation chamber at -160°C. After 5 min, when at -130°C, the samples were transferred to the SEM cham-the temperature rose to -130°C, the samples were fractured. ber and observed at -160°C with a cryo scanning electron
Figure 6. Begonia obliquifolia S. H. Huang & Y. M. Shui. A, B, Habit and habitat; C, Specimen; D, Inflorescence, showing staminate flower; E, Carpellate flower from specimen; F, Fruit; G, Fruit, middle cross section; H, Seed SEM microphotograph. All but E from C.-I Peng et al. 20506 (HAST), E fromXiao-Bai Jin 165 (PE).
PENG et al. — Begonia chongzuoensis, a new calciphile from Guangxi, China
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Table 1. Comparison of Begonia chongzuoensis with B. obliquifolia.


B. chongzuoensis (Figures 1, 2)

B. obliquifolia (Figure 6)

Rhizome


Internode length (mm)
(3.5-)5-10(-12)
(4-)5-10(-11)
Indumentum
Subglabrous
Pilose
Stipules
With red venation
Without red venation
Petioles
Sparsely hirsute-villous
Densely pilose
Leaf
Apex
Acuminate or shortly so
Acuminate
Adaxial surface
Nearly flat (Figure 5A)
Rugose (Figure 5D)
Indumentum on adaxial surface
Moderately to sparsely setulose (Figure 5A)
Densely hispidulous (Figure 5D)
Peduncle
Indumentum
Glabrous
Glandular pilose
Length (cm)
5-12
11-24
Outer staminate tepals
Glabrous
Glandular pilose
Stamen number
25-35
9-13
Ovary and fruit
Shape
Trigonous-ellipsoid
Trigonous-obovoid
Abaxial wing
Crescent-shaped
Obliquely subtriangular
Indumentum
Glabrous
Glandular pilose
Distribution
China. Guangxi: Chongzuo Shi
China. Yunnan: Malipo Xian

microscope (FEI Quanta 200 SEM/Quorum Cryo System PP2000TR FEI). Voucher specimens (Begonia chong-zuoensis: C.-I Peng et al. 20390; B. obliquifolia: C.-I Peng et al. 20506) have been deposited at HAST.
Cytology. The somatic chromosome number at metaphase of Begonia chongzuoensis was determined to be 2n = 30 (Figure 3). Among the 30 chromosomes, four were comparatively longer, ca. 1.5 to 1.9 (m, than the others (Figure 3A: arrows; 3B: Nos. 1-4); the remaining 26 chromosomes gradually varied from about 0.7 to 1.2 (m long. The four longer chromosomes were clearly metacentric, but the centromeric positions of some shorter chromosomes could not be resolved. Satellites were not observed.
The somatic chromosome number of all 18 taxa of Begonia in sect. Coelocentrum are uniformly 2n = 30 (Fang et al., 2006; Ku et al., 2004, 2006, 2008; Liu et al., 2005, 2007; Peng et al., 2005a,b, 2007, 2008a,b). Our data reveal four taxa, namely B. arachnoidea, B. kui, B. ningmingensis var. bella and B. pengii, to have two remarkably long metacentric chromosomes (Fang et al., 2006; Ku et al., 2008; Peng et al., 2007, 2008b).
Leaf anatomy and vestiture. Adaxial surface with multiseriate trichomes 0.7-1.2 mm long (Figure 5A); upper epidermal cells conoidal; epidermis single-layered on both surfaces; hypoderm absent (Figure 5B). Abaxial surface with intermixed multiseriate trichomes and unicellular (globose) or bicellular (upper cell globose) microtrichomes near the veins (Figure 5C), a unique character shared
only by two other species in sect. Coelocentrum: B. asteropyrifolia Y. M. Shui & W. H. Chen and B. variifolia Y. M. Shui & W. H. Chen. Stomatal complex single, helicocytic, subsidiary cells 5 or 6, moderately elevated (Figure 5C).
Morphological notes. Begonia chongzuoensis somewhat resembles B. obliquifolia S. H. Huang & Y. M. Shui (Figure 6), from which it differs by the moderately to sparsely setulose upper leaf surface; glabrous inflorescences, flowers and fruits, and crescent-shaped abaxial wing of the fruit. Detailed comparison of B. chongzuoensis with B. obliquifolia is presented in Table 1.
Acknowledgments. We thank Ming-Chao Yu (HAST) for the fine line drawings. This study was supported in part by the National Natural Science Foundation of China (Grant no. 41161011) to Yan Liu (IBK) and grants from the National Science Council, Taiwan and Academia Sinica to Ching-I Peng.
LITERATURE CITED
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.
Hughes, M., R.R. Rubite, Y. Kono, and C.-I Peng. 2011. Begonia
blancii (sect. Diploclinium, Begoniaceae), a new species
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endemic to the Philippine island of Palawan. Bot. Stud. 52:
203-209.
Ku, S.M., C.-I Peng, and Y. Liu. 2004. Notes on Begonia (sect. Coelocentrum, Begoniaceae) from Guangxi, China, with the report of two new species. Bot. Bull. Acad. Sin. 45: 353­367.
Ku, S.M., Y. Liu, and C.-I Peng. 2006. Four new species of Be­gonia sect. Coelocentrum (Begoniaceae) from limestone areas in Guangxi, China. Bot. Stud. 47: 207-222.
Ku, S.M., Y. Kono, and Y. Liu. 2008. Begonia pengii (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Stud. 49: 167-175.
Liu, Y., S.M. Ku, and C.-I Peng. 2005. Begonia picturata (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Bull. Acad. Sin. 46: 367-376.
Liu, Y., S.M. Ku, and C.-I Peng. 2007. Begonia bamaensis (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Stud. 48: 465-473.
Levan, A., K. Fredga, and A.A. Sandberg. 1964. Nomenclature for centromeric position on chromosomes. Hereditas 52:
201-220.
Nguyen, Q.H., C.-I Peng, and S.M. Ku. 2010. Begonia vietna-mensis, an attractive new species with peltate leaves from Vietnam. Begonian 77: 18-21.
Peng, C.-I, and S.M. Ku. 2009. Begonia ^chungii (Begoniaceae), a new natural hybrid in Taiwan. Bot. Stud. 50: 241-250.
Peng, C.-I, Y.M. Shui, Y. Liu, and S.M. Ku. 2005a. Begonia
fangii (sect. Coelocentrum, Begoniaceae), a new species
from limestone areas in Guangxi, China. Bot. Bull. Acad.
Sin. 46: 83-89.
Peng, C.-I, S.M. Ku, and W.C. Leong. 2005b. Begonia liuyanii (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Bull. Acad. Sin.
46: 245-254.
Peng, C.-I, W.C. Leong, and Y.M. Shui. 2006a. Novelties in
Begonia sect. Platycentrum for China: B. crocea, sp. nov. and B. xanthina Hook., a new distributional record. Bot.
Stud. 47: 89-96.
Peng, C.-I, W.C. Leong, S.M. Ku, and Y. Liu. 2006b. Begonia
pulvinifera (sect. Diploclinium, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Stud.
47: 319-327.
Peng, C.-I, T.Y. Hsieh, and Q.H. Ngyuen. 2007. Begonia kui (sect. Coelocentrum, Begoniaceae), a new species from
Vietnum. Bot. Stud. 48: 127-132.
Peng, C.-I, Y. Liu, and S.M. Ku. 2008a. Begonia aurantiflora (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Stud. 49: 83-92.
Peng, C.-I, S.M. Ku, Y. Kono, K.F. Chung, and Y. Liu. 2008b.
Two new species of Begonia (sect. Coelocentrum, Begoniaceae) from limestone areas in Guangxi, China: B. arachnoidea and B. subcoriacea. Bot. Stud. 49: 405-418.
Peng, C.-I, Y. Liu, S.M. Ku, Y. Kono, and K.F. Chung. 2010.
Begonia xbreviscapa (Begoniaceae), a new intersectional natural hybrid from limestone areas in Guangxi, China. Bot.
Stud. 51: 107-117.
中國秋海棠屬側膜組(秋海棠科)新種:崇左秋海棠
彭鏡毅1 古訓銘1 河野淑子1 劉演2
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
本文報導中國廣西壯族自治區石灰岩地區的秋海棠屬側膜組(Begonia sect. Coelocentrum)—新
種:崇左秋海棠(B. chongzuoensis Yan Liu, S. M. Ku & C.-I Peng)。本硏究除提供線繪圖與彩色照
片以資辨識外,並報導其染色體數 (2nn = 30)。崇左秋海棠與產於雲南省麻栗坡縣的斜葉秋海棠 (B.
obliquifolia)略似,但前者葉片之上表面具中度至稀疏的短刺毛、花序各部與果實皆光滑無毛,以及果
實背翅爲新月形 (上緣爲圓形) 可資區別。目前僅知其族群分布於廣西西南部的一個陡峭的石灰岩山,
爲稀有植物。
關鍵詞:崇左秋海棠;斜葉秋海棠;側膜組;秋海棠科;中國;染色體數;廣西;石灰岩植物;新種;
稀有植物。