Botanical Studies (2008) 49: 167-175.

*

Corresponding author: E-mail: gxibly@163.com; Tel:

+86-7733550090.

TAXONOMY

Begonia pengii (sect. Coelocentrum, Begoniaceae), a

new species from limestone areas in Guangxi, China

Shin-Ming KU

1

, Yoshiko KONO

1

, and Yan LIU

2,

*

1

Herbarium (HAST), Research Center for Biodiversity, Academia Sinica, Nangang, Taipei 115, Taiwan

2

Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences, Guilin

541006, China

(Received September 5, 2007; Accepted March 7, 2008)

ABSTRACT.

Begonia pengii, a new species from Guangxi Zhuangzu Autonomous Region, China, is here

described and illustrated. Its somatic chromosome number (2n = 30) and karyotype are reported. Begonia

pengii belongs to sect. Coelocentrum and somewhat resembles B. variifolia Y. M. Shui & W. H. Chen, from

which it differs by its much larger size, leaves (11-)15-27 × (6-)8-15 cm, narrowly ovate, peduncle 17-37 cm;

anther sacs red margined; and capsules 1.8-2.5 cm long. Like most members of sect. Coelocentrum, B. pengii

is an attractive species and is rare, known only from one steep limestone hill in western Guangxi.

Keywords: Begonia luochengensis; Begonia pengii; Begonia picturata; Begonia sect. Coelocentrum; Begonia

variifolia; Begoniaceae; China; Chromosome number; Guangxi; Karyotype; Limestone flora; New species;

Rare species.

INTRODUCTION

The spectacular karst limestone landform in Guangxi,

China is home to many endemic and rare species. As

a result of our continued fieldwork in Guangxi and

research on Begonia, an attractive new species of sect.

Coelocentrum was discovered, which is described below.

MATERIALS AND METHODS

Cryo scanning electron microscopy

Fresh leaves of Begonia pengii were dissected and

attached to a stub. The samples were frozen with liquid

nitrogen slush, then transferred to a sample preparation

chamber at -160°C. After 5 min, when the temperature

rose to -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 Quanta 200 SEM/Quorum Cryo System

PP2000TR FEI).

Chromosome preparations

Root tips of Begonia pengii were pretreated with 2

mM 8-hydroxyquinoline solution at 15-18°C for about 8

h and fixed in ethanol-acetic acid (3:1) at about 4°C for

more than 24 h. Chromosome preparations were made

by the enzyme squash method in an enzyme mixture of

4% Cellulase (Onozuka R-10, Yakult) and 2% Pectolyase

Y-23 (Kyowa Chemical Products) at about 37°C for 1 h.

The preparations were stained with 2% Giemsa solution

(Merck). Classification of the chromosome complements

based on centromere position at mitotic metaphase follows

Levan et al. (1964). The voucher specimen has been

deposited in HAST.

NEW SPECIES

Begonia pengii S. M. Ku & Yan Liu, sp. nov. —TYPE:

CHINA. Guangxi Zhuangzu Autonomous Region,

Bama Xian, Xishan. Sheltered, vertical limestone rock

face, ca. 500 m alt. 18 May 2007, Ching-I Peng, Yan

Liu, Kuo-Fang Chung, Ming-Chao Yu & Hai-Shan

Gao 21070 (holotype: HAST; isotype: IBK).

彭氏秋海棠 Figures 1, 2, 3A

Begoniae variifoliae Y. M. Shui & W. H. Chen affinis,

sed foliis anguste ovatis, antherarum saccis rubro-

marginatis, habitu multo majore [foliis (11-)17-27

× (6-)8.5-15 cm, pedunculis 17-30 cm longis, capsulis

1.8-2.5 cm longis] differt.

Herbs, monoecious, epipetric, perennial, rhizomatous.

Rhizome 6-15 cm or longer, (5-)9-12(-18) mm thick,

internodes (5-)7-10(-12) mm long, brown or reddish

brown, villous near base of petiole and leaf scars. Stipules

eventually caducous, narrowly triangular-ovate, 12-15 mm

long, 5-8 mm wide, reddish hyaline, herbaceous, weakly

or not keeled, glabrous, margin eciliate, apex aristate,

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Botanical Studies, Vol. 49, 2008

Figure 1. Begonia pengii S. M. Ku & Yan Liu. A, Habit; B, Portion of leaf, adaxial surface, showing margin and indumentum, B’,

abaxial surface, B’’, cross section; C, Stipule; D, Bract; E, Staminate flower, face view, E’, side view; F. Androecium; G, G’, G’’,

Stamens; H, Carpellate flower, face view, H’, side view; I, I’, II’’, Style and stigma; J, Dry capsule; K, Capsule, cross section; L, Seeds.

All but A, J from Peng et al. 20724 (HAST); A, J from Peng et al. 21070 (HAST).

KU et al. —

Begonia pengii

, a new species from China

169

Figure 2. Begonia pengii S. M. Ku & Yan Liu. A, Habit; B, Rhizome; C, Leaf adaxial surface; D, Leaf abaxial surface; E, Stipule;

F, Bract; G, Staminate flower, face view; H, Androecium, showing red-margined anther sacs; I, Carpellate flower, face view; J, Young

capsule; K, Dry capsule; L. Middle cross section of a young fruit. All but C-F, K from Peng et al. 21070 (HAST); C-F, K from Peng et

al. 20724 (HAST).

170

Botanical Studies, Vol. 49, 2008

Figure 3. Holotype specimens. A, Begonia pengii, C.-I Peng et al. 21070 (HAST); B, Begonia variifolia, Y. M. Shui & W. H. Chen

B2004-202 (KUN).

arista 3-5 mm long, hair-like. Leaves 2-8, alternate, simple,

asymmetric, unlobed, narrowly ovate, base peltate (rarely

subpeltate), margin crenate-denticulate and ciliate, apex

acuminate to caudate, (11-)17-27 cm long (basal lobes

included), (6-)8.5-15 cm wide, surface usually adorned

with a wide whitish or pale silvery band (to 2 cm across)

along midrib, pale green or whitish along major veins and

major lateral veins, dark brownish to purplish red between

major veins and major lateral veins, texture papery, surface

rugulose, adaxially densely pilose (trichomes 0.7-1.2(-2)

mm long, whitish-hyaline or reddish), abaxially villose-

pilose, particularly pronounced on veins; venation

basally 6-7-palmate, midrib distinct, veins pinnate along

midrib, with 1-3 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 75-100° to major veins, minor

veins reticulate, all veins on abaxial surface prominently

raised; petiole terete, (10-)15-26 cm long, 3-6.5 mm thick,

brownish or brownish red, hirsute-villous. Inflorescences

axillary, dichasial cymes 1-3 or more, arising directly

from rhizome, branched 2 to 3 times. Flowers 4-12 per

inflorescence; staminate flowers 3-9, carpellate flowers

1-3; peduncle well developed, terete, erect or ascending,

17-37 cm long, 1.5-3 mm thick, brownish or reddish

brown, densely pilose or hispid-villous. Bracts caducous,

oblong, ovate or broadly ovate, margin denticulate and

ciliate, apex obtuse or acute, 4-15 mm long, 3-7 mm

wide. Staminate flowers: pedicel 1-2 cm long, pilose to

hispid; tepals 4, outer 2 broadly ovate or suborbicular,

base rounded or slightly cordate, margin usually ciliate,

apex rounded, 17-21 mm long, 15-20 mm wide, pinkish or

white, abaxially densely pilose (trichomes whitish); inner

2 tepals obovate or elliptic, base cuneate, margin entire,

eciliate, apex obtuse or rounded, 13-17 mm long, 7-10.5

mm wide, white, glabrous; androecium zygomorphic,

subglobose, stamens 30-75, golf-club-shaped; filaments

subequal, 1.5-1.7 mm long, partly fused at base; anthers

± ascending, 2-locular, slightly compressed, obovoid or

oblong-obovoid, connective apex slightly emarginate,

1-1.2 mm long, 0.7-0.8 mm wide, yellow with red margins

along anther sacs. Carpellate flowers: pedicel 15-20 mm

long, horizontally spreading to pendent, bracteole absent;

tepals 3, caducous, outer 2 tepals suborbicular or oblate-

ovate, margin ciliate at lower part or sometimes eciliate,

15-18 mm long, 18-20 mm wide, pinkish or white,

abaxially densely pilose; inner tepal elliptic or broadly

lanceolate, base cuneate, apex obtuse, 9-10 mm long, 6-7

mm wide, white or pinkish, glabrous; ovary trigonous-

ellipsoid, ca. 8 mm long, 5-6 mm thick (wings excluded),

KU et al. —

Begonia pengii

, a new species from China

171

pilose or villous-pilose, 3-winged; 1-locular with intruded

parietal placentation (axile at base); placentae 3, each

2-branched (T-shaped); styles 3, nearly free, yellow, ca.

4 mm long, apically C-shaped; stigmatic band spiraled.

Capsule nodding, trigonous-ellipsoid, somewhat curved,

18-25 mm long, 6-13 mm thick (wings excluded), apex

with persistent styles; wings unequal; lateral wings 2-3

mm tall; abaxial wing crescent-shaped or nearly so, 7-11

mm tall. Seeds numerous, brown, ellipsoid or narrowly

so, 0.56-0.68 mm long, 0.29-0.32 mm thick, chalazal end

rounded, micropylar end obtuse or slightly constricted,

outer periclinal walls of mature seeds concave; collar

cells elongated, straight, nearly rectangular, 11-14 cells

in a ring, occupying 1/4-1/2 of seed length. Somatic

chromosome number, 2n = 30 (Figure 4).

Additional specimens examined. CHINA. Guangxi

Zhuangzu Autonomous Region, Bama Xian, Xishan,

Limestone rock face, ca. 500 m alt. (same loc. as the type

collection), 17 Dec 2005, Ching-I Peng, Shin-Ming Ku,

Yan Liu, and Tsung-Han Tsai 20724 (HAST).

Habitat and Ecology. Begonia pengii was found in

small populations on vertical, usually sheltered, rock faces

in evergreen forests on jagged limestone hills.

Distribution. Endemic to western Guangxi, China

(Figure 5); rare.

Etymology. We dedicate this new, handsome species of

Begonia to Dr. Ching-I Peng, mentor of the first author.

The specific epithet recognizes his emphatic interest and

substantial contribution to the study of Asiatic Begonia.

Heretofore, Dr. Peng and his associates have described 27

new species of Begonia (Peng et al., 1988; Peng and Chen,

1990; Peng and Sue, 2000; Ye et al., 2004; Ku et al., 2004;

Peng et al., 2005a, b, c; Liu et al., 2005; Li et al., 2005;

Peng et al., 2006a, b; Fang et al., 2006; Ku et al., 2006;

Peng et al., 2007; Liu et al., 2007; Peng et al., 2008), many

of which are of great horticultural potential.

Leaf anatomy and vestiture. Adaxial surface with

multiseriate trichomes 0.7-1.2 mm long (Figure 6A,

B); upper epidermal cells conoidal; epidermis single-

layered on both surfaces, hypoderm absent (Figure 6C).

Abaxial surface with intermixed multiseriate trichomes

and unicellular (globose) or bicellular (upper cell globose)

microtrichomes near the veins (Figure 6D, E), a unique

character shared only by two other species in sect.

Coelocentrum: B. asteropyrifolia Y. M. Sh ui & W. H.

Chen and B. variifolia Y. M. Shui & W. H. Chen (Ching-I

Peng, pers. comm.). Stomatal complex single, helicocytic,

subsidiary cells (5-)6, moderately elevated (Figure 6F).

Phenology. Flowering from Mar to June; fruiting from

June to Dec.

Figure 4. Karyomorphology of Begonia pengii. A, Somatic chromosomes at metaphase, 2n = 30; B, Karyotype: chromosomes pairs

arranged by decreasing order of length (from Peng et al. 20724).

Figure 5. Distribution of Begonia pengii (★), B. variifolia

(●), B. luochengensis (■), and B. picturata (▲) in Guangxi

Zhuangzu Autonomous Region, China.

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Botanical Studies, Vol. 49, 2008

Figure 6. Leaf SEM microphotographs of Begonia pengii: A, B, Trichomes on upper epidermis; C, Lamina, cross section; D, Lower

epidermis, showing two kinds of trichomes; E, Unicellular and bicellular microtrichomes (lower epidermis); F, Stomatal complex

(lower epidermis).

KU et al. —

Begonia pengii

, a new species from China

173

Table 1. Comparison of Begonia pengii, B. variifolia, B. luochengensis and B. picturata.

B. pengii

(Figures 1, 2, 3A)

B. variifolia (Figure 3B)

B. luochengensis

(Ku et al., 2004:

Figures 4, 5)

B. picturata (Liu et al.,

2005: Figures 1, 2)

Rhizome diam. (mm) (5-)9-12(-18)

(3-)4-6

(5-)8-15(-20)

(5-)6-12

Stipule

Indumentum

Glabrous

Glabrous

Glabrous

Abaxially villous

Margin

Eciliate

Eciliate or remotely

ciliolate

Ciliate

Ciliate

Size (mm)

12-15 × 5-8

5-6 × 3-5

7-10 × 7-9

5.5-23 × 6-10

Shape

Narrowly triangular-

ovate

Ovate

Triangular-ovate to

semicircle

Ovate-triangular to

lanceolate-triangular

Leaf

Size (cm)

(11-)15-23(-27) ×

(6-)8-15

5-10 × 3.5-7.2

5-20 × 7-12

(7-)10-15(-20) ×

(5.5-)7-10(-14)

Base

Peltate (rarely

subpeltate)

Peltate, subpeltate to

basifixed

Basifixed

Basifixed

Maculation

With a prominent white

band along midrib; pale

green or white along

major veins and lateral

veins; usually dark

brownish to purplish

red between major

veins

With or without a

narrow white band

along midrib, pale

green along major

veins and major

lateral veins; green

or brownish between

major veins

With a prominent

white band along

midrib, pale green

along major veins

and lateral veins,

dark brownish

to purplish red

between major

veins

With a wide white,

greenish-white, or

pale green ring in

the middle or with

digitate dark brown

bands along main

veins and at leaf

margin, pale green,

yellowish green to

whitish elsewhere

Tertiary venation Reticulate and percurrent Reticulate and

percurrent

Ramified or loosely

reticulate, not

percurrent

Reticulate and

percurrent

Peduncle

Indumentum

Densely pilose or hispid-

villous

Pilose to hirsute-villous Glabrous

Villous

Length (cm)

17-37

7.5-21

8-22

10-16

Outer staminate tepals Densely pilose, usually

ciliate

Densely pilose, usually

eciliate

Glabrous, eciliate Hirsute, eciliate

Anther sac

Yellow with red margins Yellow throughout Yellow throughout Yellow with red

margins

Capsule

Size (mm)

18-25

×

6-13

8-14 × 4-6

11-17 × 6-7

10-15 × 6-8

Indumentum

Pilose or villous-pilose Pilose or villous-pilose Glabrous

Villous-setose or

hispid-setose

Chromosome cytology. Somatic chromosomes at

mitotic metaphase of Begonia pengii were determined

t o be 2 n = 30 (Figure 4). The chromosomes showed a

bimodal variation in length. Of the 30 chromosomes,

two were about 2 μm long (Figure 4-B: nos. 1 and 2); the

remaining 28 were shorter, ranging from about 0.9-1.4

μm in length. While the position of the centromere of

some shorter chromosomes was unclear, the two longest

chromosomes had centromere in the median position.

Satellite chromosomes were not observed.

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Botanical Studies, Vol. 49, 2008

The chromosome number of all 14 taxa of Begonia in

sect. Coelocentrum reported earlier are uniformly 2n = 30

(Fang et al., 2006; Ku et al., 2004, 2006; Liu et al., 2005,

2007; Peng et al., 2005a, 2005b, 2007, 2008). Two taxa,

B. ningmingensis var. bella and B. kui, clearly showed

bimodal variation in chromosome length (Fang et al.,

2006; Peng et al., 2007).

Morphological notes. Begonia pengii is similar to B.

variifolia (Shui and Chen, 2005), differing in the much

larger size, leaves (11-)15-27 × (6-)8-15 cm (vs. 5-10

× 3.5-7.2 cm), narrowly ovate (vs. broadly ovate to

ovate), peduncle 17-30 cm (vs. 7.5-21 cm); margin of

the anther sacs red; and capsules 1.8-2.5 cm (vs. 0.8-1.4

cm). Begonia sect. Coelocentrum comprises more than 40

species. Red-margined anther sacs are known only in B.

pengii and B. picturata. Detailed comparison of B. pengii

with related species is presented in Table 1.

Acknowledgments. We thank Qiner Yang (PE) for the

Latin diagnosis; David E. Boufford (A/GH) and Thomas

G. Lammers (OSH) for improving the manuscript; De-

Zhu Li (KUN) for facilitating the loan of Begonia types;

Hai-Shan Gao (IBK), Kuo-Fang Chung, Tsung-Han Tsai

(HAST) for field assistance; and Ming-Chao Yu (HAST)

for the handsome line drawings and field assistance.

This study was supported in part by a Personnel Training

Plan of West Light Foundation of the Chinese Academy

of Sciences (2007) to Yan Liu (IBK) and grants from th e

National Science Council and Academia Sinica, Taiwan

to Ching-I Peng (HAST).

LITERATUR 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.

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:

353-367.

Ku, S.M., Y. Liu, and C.-I P eng. 2006. Four new species of

Begonia sect. Coelocentrum (Begoniaceae) from limestone

areas in Guangxi, China. Bot. Stud. 47: 207-222.

L i, H.J., H. Ma, K.Y. Guan, and C.-I Peng. 2005. B egonia

rubinea (sect. Platycentrum, Begoniaceae), a new species

from Guizhou, China. Bot. Bull. Acad. Sin. 46: 377-383.

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 chromosom e. Hereditas 52:

201-220.

P eng, C.-I, Y.K. Chen, and H.F. Yen. 1988. Begonia ravenii

(Begoniaceae), a new species from Taiwan. Bot. Bull. Acad.

Sin. 29: 217-222.

P eng, C.-I and Y.K. Chen. 1990. Begonia aus trotaiwanensis

(Begoniaceae), a new s pecies from southern Taiwan. J.

Arnold Arb. 71: 567-574.

P eng, C.-I a nd C.Y. Sue. 2000. Begonia ×taipeiensis P eng

(Begoniaceae), a new hybrid in Taiwan. Bot. Bull. Acad.

Sin. 41: 151-158.

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

(s ect. Coelocentrum, Begoniaceae), a new species from

limestone areas in Guangxi, China. Bot. Bull. Acad. Sin.

46: 245-254.

Peng, C.-I, Y.K. Chen, and W.C. Leong. 2005c. Five new species

of Begonia (Begoniaceae) from Taiwan. Bot. Bull. Acad.

Sin. 46: 255-272.

P eng, 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 (sec t. Diploclinium, Begoni acea e), 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

Vietnam. Bot. Stud. 48: 127-132.

Peng, C.-I, Y. Liu, and S.M. Ku. 2008. Begonia aurantiflora

(sect. Coelocentrum, Begoniaceae), a new species from

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KU et al. —

Begonia pengii

, a new species from China

175

中國廣西石灰岩地區秋海棠屬側½組新種：彭氏秋海棠

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的秋海棠屬側½組 (Begonia sect. Coelocentrum) 一新種：彭氏秋海棠

(Begonia pengii)。本研究除提供½繪圖與彩色照片以資辨識外，並報導其染色體數 (2n = 30) 與核型。彭

氏

秋海棠與多變秋海棠 (B. variifolia) 略似，

但植株明顯碩大：葉片大小為 (11-)15-27 × (6-)8-15 cm (後者

5-10 × 3.5-7.2 cm)，總花梗長 17-37 cm (後者7.5-21 cm)，蒴果長 1.8-2.5 cm (後者 0.8-1.4 cm)；此外，葉

片常呈狹卵形

（

非廣卵形至卵形）、雄蕊之藥囊邊½為紅色

（

非黃色

）

，明顯與

多變秋海棠

有別。彭氏

秋海棠之體態及葉片斑紋皆美，目前僅知其族群分布於廣西西部－個陡峭的石灰岩山，為稀有植物。

關鍵詞：羅城秋海棠；彭氏秋海棠；一口血秋海棠；多變秋海棠；秋海棠屬側½組；秋海棠科；中國；

染色體數；廣西；核型；石灰岩植物；新種；稀有植物。