Botanical Studies (2008) 49: 405-418.

*

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

+86-7733550090.

INTRODUCTION

Renowned for the spectacular scenery of limestone

karsts, Guangxi Zhuangzu Autonomous Region of

southern China also abounds in marvelous botanical

diversity. As the third most species-rich province/region

in China, surpassed only by Yunnan and Sichuan,

Guangxi is also characterized by extremely high levels of

endemism associated with its extensive limestone habitats.

In continuation of our research on Asian Begonia (e.g.,

Fang et al., 2006; Gu et al., 2007; Ku et al., 2004, 2006,

2008; Li et al, 2005; Liu et al., 2005, 2007; Peng et al.,

2005-a,b,c, 2006-a,b, 2007, 2008), we report two new

species from limestone hills in southwestern Guangxi.

MATERIALS AND METHODS

Cryo scanning electron microscopy

Fresh leaves of Begonia arachnoidea, B. umbraculi-

folia and B. subcoriacea were dissected and attached to a

stub. The samples were frozen with liquid nitrogen slush,

then transferred to a sample preparation chamber at -160

¢XC. After 5 min, when the temperature rose to -130¢XC, the

samples were fractured. The samples were etched for 10

min at -85¢XC. After coating at -130¢XC, the samples were

transferred to the SEM chamber and observed at -160¢XC

with a cryo scanning electron microscope (FEI Quanta

200 SEM/Quorum Cryo System PP2000TR FEI). Voucher

specimens have been deposited at HAST.

Chromosome preparations

Root tips of Begonia arachnoidea, B. umbraculifolia

and B. subcoriacea were pretreated with 2 mM 8-hydroxy-

quinoline solution at 15-18¢XC for about 8 h and fixed in

ethanol-acetic acid (3:1) at about 4¢XC 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¢XC for 1 h. The prepara-

tions were stained with 2% Giemsa solution (Merck).

Voucher specimens have been deposited at HAST.

Two new species of Begonia (sect. Coelocentrum,

Begoniaceae) from limestone areas in Guangxi, China:

B. arachnoidea and B. subcoriacea

Ching-I PENG

1

, Shin-Ming KU

1

, Yoshiko KONO

1

, Kuo-Fang CHUNG

2

, and Yan LIU

3,

*

1

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

2

School of Forestry and Resource Conservation, National Taiwan University, Daan, Taipei 106, Taiwan

3

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

541006, P.R. China

(Received January 11, 2008; Accepted August 1, 2008)

ABSTRACT.

Begonia arachnoidea and B. subcoriacea, two new species of Begonia sect. Coelocentrum

from the karst area in Guangxi Zhuangzu Autonomous Region, China, are described and illustrated. Begonia

arachnoidea is similar to B. umbraculifolia in the peltate leaves with the venation in a spider web-like pattern,

differing by rhizomes stout, internodes congested, stipules ovate-triangular, leaves adaxially densely shortly

setose and hispid-setulose, abaxially densely hispidulous-pilose on all veins, pedicel of carpellate flower longer

and with a bracteole. Begonia subcoriacea is similar to B. liuyanii in the small flowers, differing

by

smaller

habit; leaves adaxially glabrous, abaxially tomentose only on major veins, tertiary leaf venation flat; outer

tepals glabrous or subglabrous, and

inflorescence

a dichasial cyme. Both new species are rare and endemic to

Guangxi. A somatic chromosome number of 2n = 30 is here reported for B. arachnoidea, B. umbraculifolia

and B. subcoriacea.

Keywords: Begonia arachnoidea; Begonia liuyanii; Begonia subcoriacea; Begonia umbraculifolia; Begonia

umbraculifolia var. flocculosa

;

Begoniaceae; China; Chromosome number; Guangxi; Limestone flora; New

species; Rare species; sect. Coelocentrum.

TAXONOMY

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Botanical Studies, Vol. 49, 2008

NEW SPECIES

1. Begonia arachnoidea C.-I Peng, Yan Liu & S. M.

Ku, sp. nov.¡XTYPE: CHINA. Guangxi Zhuangzu

Autonomous Region, Daxin Xian (County), Encheng

Xiang, Encheng Nature Reserve, elev. ca. 200 m, mixed

bamboo and scrubby vegetation at foot of limestone

hill, on semishaded rocky slope, occasional. Plant

sterile when collected on 27 May 2004. Flowering

specimens pressed from cultivated plant on 12 Oct

2005, Ching-I Peng, Wai-Chao Leong, Shin-Ming Ku

& Yan Liu 19762-A (holotype: IBK; isotype: HAST).

µïºô¯ß¬î®ü´Å Figures 1, 2

Figure 1. Begonia arachnoidea C.-I Peng, Yan Liu & S. M. Ku. A, Habit; B, Portion of leaf, adaxial surface, B¡¦, abaxial surface, B¡¦¡¦,

cross section; C, Stipule; D, Bract; E, Staminate flower, face view, E¡¦, side view; F, Androecium; G, Stamen, ventral view, G¡¦, side

view, G¡¦¡¦, dorsal view; H, Carpellate flower, face view, H¡¦, side view; I, Style and stigma, I¡¦, dorsal view, I¡¦¡¦, ventral view; J, Fruit; K,

Fruit, Middle cross section. (All from the type, C.-I Peng et al. 19762-A).

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

407

Figure 2. Begonia arachnoidea C.-I Peng, Yan Liu & S. M. Ku. A, Habit and habitat; B, Habit, at anthesis; C, Leaf, abaxil surface; D,

Stipule; E. Portion of leaf, cross section; arrow indicating tertiary veins; F, Portion of leaf, showing trichomes on adaxial surface; G,

Portion of leaf, showing trichomes on abaxial surface; H, Rhizome, showing congested internodes; I, Inflorescence with opened stami-

nate flowers and unopened carpellate flowers, showing pendent carpellate flowers with long pedicel, arrow indicating bracteole; J, Sta-

minate flower, face view; K, Staminate flower, side view; L, Carpellate flower bud, arrow indicating bracteole; M, Carpellate flower; N,

Trichomes on ovary surface; O, Fruit; P, Cross section of an immature fruit. (All from the type, C.-I Peng et al. 19762-A).

408

Botanical Studies, Vol. 49, 2008

1-locular with parietal placentation, each placenta with 2

lamellae;

styles 3, ca. 4 mm long, fused at base, stigma

spirally twisted and papillose all around. Fruits nodding,

1.3-2.6 cm long, 0.5-0.6 cm across. Somatic chromosome

number, 2n = 30 (Figure 3A).

Additional specimens examined. CHINA. Daxin Xian,

Encheng Xiang, Encheng Nature Reserve, elev. ca. 200

m, mixed bamboo and scrubby vegetation, at foot of

limestone hill, on rocky slope, semishaded, occasional.

(Same locality as the type.) Plant sterile when collected.

27 May 2004, Ching-I Peng, Wai-Chao Leong, Shin-Ming

Ku & Yan Liu 19762 (HAST).

Leaf anatomy and vestiture. Cross section 0.2-0.35 mm

thick. Adaxial surface with many multiseriate trichomes

0.2-1 mm long, the larger trichome surrounded by many

smaller trichomes (Figure 4A); upper epidermal cells with

slightly conoidal surface. Aabaxial surface with intermixed

uniseriate and multiseriate trichomes on veins and venlets

(Figure 4B). Epidermis single layered on both surfaces,

hypoderm absent. Lower stomatal complex single, slightly

elevated, helicocytic type, subsidiary cells 5-6 (Figure 4C).

Phenology. Flowering from September to October,

fruiting from October to December.

Distribution. Daxin Xian, southwestern Guangxi, China

(Figure 5).

Etymology. The specific epithet indicates that its leaf

venation resembles a spiderweb.

Notes. Begonia arachnoidea resembles B .

umbraculifolia (Figures 6, 7) in the peltate leaves and the

venation in a spiderweb-like pattern, differing by rhizomes

stout, internodes congested, stipules ovate-triangular,

leaves adaxially densely shortly setose and hispid-setulose,

abaxially densely hispidulous-pilose on all veins, pedicel

of carpellate flower 4-6 mm and with a bracteole. In

Begonia umbraculifolia the rhizomes are slender; stipules

are narrowly ovate-triangular to lanceolate; leaves are

sparsely pilose on both surfaces; pedicels of carpellate

flowers are 3.5-4 cm long and ebracteolate). A detailed

comparison of the two species are provided in Table 1.

Begonia arachnoidea was collected from the same

county (Daxin Xian) as the type collection of Begonia

umbraculifolia var. flocculosa Y. M. Shui & W. H. Chen

(Shui and Chen, 2005). Shui & Chen¡¦s holotype (KUN!),

however, is represented merely by a piece of leaf and

their sketchy diagnosis does not offer enough information

for positive identification. Tentatively, we consider B.

umbraculifolia var. flocculosa to be a possible synonym.

2. Begonia

subcoriacea C.-I Peng, Yan Liu, S. M. Ku, sp.

nov.¡X TYPE: China. Guangxi Zhuangzu Autonomous

Region, Daxin Xian, between Longhua and Niandi,

elev. ca. 250 m, N-facing, broadleaf forest with scat-

tered bamboo groves, on semishady limestone slope,

25 May 2007, Ching-I Peng, Kuo-Fang Chung, Ming-

Chao Yu & Hai-Shan Gao 21135 (holotype: IBK; iso-

type: HAST). ªñ­²¸­¬î®ü´Å

Figures 8, 9

Possible synonym. Begonia umbraculifolia var.

flocculosa Y. M. Shui & W. H. Chen, Acta Bot. Yunnan.

27(4): 372. 2005.

Begonia arachnoidea aspectu similis B .

umbraculifoliae, sed rhizomatibus crassioribus, internodiis

congestis, stipulis ovato-triangularibus, foliis adaxialiter

dense breviterque setosis et hispido-setulosis, abaxialiter

ad venas dense hispidulo-pilosis, pedicellis florum

carpellatorum longioribus differt.

Herbs, monoecious, rhizomatous; rhizome stout,

creeping, 1.1-2 cm thick, internode 0.5-1 cm long.

Leaves peltate, basal; stipules caducous, ovate-triangular,

0.7-0.9 cm long, 0.7-1.1 cm wide; petiole 13-26(-30)

cm long, hirsute-villous (the hairs 2-5.5 mm long);

leaf

blade suborbicular or broadly ovate, 12-26(-35) cm long,

11-19(-27) cm wide, papery, adaxially deeply green or

brownish, with white or pale band along major veins (the

band often composed of small, dense white spots), densely

shortly setose and hispid-setulose (trichomes 0.2-0.9

mm long),

abaxially densely hispidulous-pilose on all

veins (trichomes reddish with red base, 0.3-0.8 mm long,

somewhat unevenly spread and ragged),

base rounded,

slightly oblique, margin shallowly unequally serrulate or

undulate, apex acute to shortly acuminate;

venation basally

6- or 7-palmate, tertiary veins percurrent, spiderweb-

like.

Inflorescences axillary; peduncle

9-31 cm long,

moderately hispid-villous; flowers white, 6-24 in dichasial

cymes;

bracts caducous, ovate or oblong,

5-7 cm long 5-6

mm wide, margin serrate-ciliate, apex obtuse. Staminate

flower: pedicel 0.6-3.7 cm,

pilose; tepals 4, pink, outer

2 broadly ovate, 1.1-1.9 cm long, 1-1.5 cm wide, base

subrounded, apex somewhat acute or obtuse,

outside

hirsute or hispid-pilose, inner 2 elliptic, 6-8 mm long, 3.5-5

mm wide, apex acute; stamens 26-44; filaments ca. 1.5-2

mm long; anthers obovate-oblong

,

1.1-1.4 mm;

connective

apex emarginate.

Carpellate flower: pedicel 4-6 cm, with

one bracteole,

glandular-hispidulous or sparsely so; tepals

3, pink, outer 2 suborbicular or broadly ovate, 0.9-1.5

cm long, 0.9-1.4 cm wide, apex and base rounded, inner

1 elliptic, 6-8 mm long, 3.5-4 mm wide; ovary oblong,

7-16 mm long, 4-5 mm across, moderately to sparsely

glandulose-pilose or glandulose-villous and with some or

many small stalked glandular hairs,

unequally 3-winged,

Figure 3. Mitotic chromosome spread of Begonia. A, Begonia

arachnoidea (C.-I Peng et al. 19762); B, B. umbraculifolia (C.-I

Peng et al. 19694).

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

409

Figure 4. Scanning electron microscope (SEM) micrographs of folilar trichomes and stomata complexes of Begonia arachnoidea (A,

B, C) and B. umbraculifolia (D, E, F). A, D, Leaf adaxial surface; B, E, Trichomes on vein of leaf abaxial surface; C, F, Stomatal com-

plexes on leaf abaxial surface.

410

Botanical Studies, Vol. 49, 2008

side, other primary veins dichotomously branching or

nearly so, tertiary veins reticulate or percurrent, divergence

angle 60-85¢X, minor veins reticulate, major (1¢X & 2¢X)

veins on abaxial surface prominently raised, minor veins

not raised; petiole terete, 9-20 cm long, 3-7.5 mm thick,

Begonia subcoriacea aspectu similis B. liuyanii, sed

habitu minore, foliis adaxialiter glabris, abaxialiter tantum

ad venas majores tomentosis, venis tertiariis planis, tepalis

externis glabris vel subglabris, inflorescentia dichasio-

cymosa differt.

Plant monoecious; epipetric; perennial; rhizomatous.

Rhizome rather stout, 5-15 cm long, 0.6-1.2 cm thick,

internodes 0.4-1.2 cm long, brown, villous when young,

glabrate when old

.

Stipules eventually caducous,

triangular-ovate or narrowly so, ca. 1-2 cm long, 0.8-1.4

cm wide, brownish, herbaceous

,

keeled or weakly so,

abaxially hairy (sometimes only along midrib), margin

usually ciliate or ciliolate, sometimes eciliate on upper

margin, apex aristate,

arista 3-4 mm long, somewhat horn-

like. Leaves 2-6 or more, alternate, simple, asymmetric,

unlobed, widely ovate or suborbicular, base strongly

oblique cordate, margin inconspicuously irregularly

repandly denticulate and ciliolate,

apex shortly acuminate,

(10-)12-20(-22)

cm

long (basal lobes included),

(8

-

)

10-14(-17) cm wide,

adaxially green, with or without

white maculation between major veins, abaxially pale

green, yellowish green or reddish, sometimes reddish near

the major veins, subcoriaceous, flat, adaxially glabrous

(sparsely gibbous when young), obviously nitid, abaxially

tomentose on major veins, sparsely pilose on tertiary

venation; venation basally 6-7-palmate, midrib distinct,

pinnate along midrib,

with 1-3 major lateral veins on each

Figure 5. Dis tribution of Begonia arachnoidea (¡·), B. um-

braculifolia (¡´), B. subcoriacea (¡¹), B. liuyanii (¡¶) in Guangxi

Zhuang Autonomous Region, China.

Table 1. Comparison of Begonia arachnoidea and B. umbraculifolia.

Begonia arachnoidea (Figures 1, 2)

Begonia umbraculifolia (Figures 6, 7)

Rhizome

Internode (mm)

5-10

8-14

Diameter (mm)

11-20

10-40

Stipules

Ovate-triangular

Narrowly ovate-triangular to lanceolate

Leaf

Indumentum

Adaxially densely shortly setose and hispid-

setulose (Figure 4A), abaxially densely

hispidulous-pilose on all veins (Figure 4B)

Sparsely pilose on both surfaces (Figure

4D, E)

Maculation

With white or pale bands along major veins (the

band often composed of dense, small white

spots)

Pale green or greenish near the major veins

Adventitious epiphyllous

appendages

Lacking

Sometimes on axils of major veins on

upper leaf surface

Stomatal complexes on lower

surface

Moderately dense; subsidiary cells 5-6, larger

(Figure 4C)

Less dense; subsidiary cells 3-5, rarely 6,

smaller (Figure 4F)

Outer tepals color

White or slightly pinkish

Pink

Carpellate flower

Pedicel length (mm)

40-60

27-40

Indumentum on ovary surface Mixed glandulose-pilose and minute, stalked

glandular hairy (Figure 2N)

Sparsely villous or pilose; very sparse,

minute, subsessile glands not visible by

naked eyes

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

411

Figure 6. Begonia umbraculifolia B. N. Chang & Y. Wan. A, Habit ; B, Portion of leaf, adaxial surface, B¡¦, abaxial surface; C, Portion

of leaf, showing adventitious epiphyllous appendages on major veins; D, D¡¦, Stipules; E, Bract; F, Staminate flower, face view, F¡¦, side

view; G, Androecium; H, Stamen, side view, H¡¦, dorsal view, H¡¦¡¦, ventral view; I, Carpellate flower, face view, I¡¦, side view; J & J¡¦,

Style and stigmas; K, Capsule; L, Capsule, middle cross section. (All from C.-I Peng et al. 19694).

412

Botanical Studies, Vol. 49, 2008

Figure 7. Begonia umbraculifolia B. N. Chang & Y. Wan. A, Habit and habitat; B, Habit at anthesis; C, Leaf, abaxial side; D, Leaf

margin and adaxial surface; E, Adventitious epiphyllous appendages on major veins; F, Stipules; G, Rhizhome; H, Staminate flower; I,

Carpellate flower, face view; J, Carpellate flower, side view; K, Middle cross section of ovary. (All from C.-I Peng et al. 19694).

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

413

Figure 8. Begonia

subcoriacea C.-I Peng, Yan Liu & S. M. Ku. A, Habit; B, Portion of leaf, abaxial surface; C, Portion of petiole,

showing trichomes; D, Stipule; E, Inflorescences bud, showing ciliate bracts; F, Portion of peduncle, showing glandulose-pilose tri-

chomes;

G, Staminate flower, face view; H, Androecium, longitudinal section; I-I¡¦, Stamen, ventral view and dorsal view; J, Carpel-

late flower; K, Style and stigma; L, Dry fruit; M, Middle cross section of a young fruit, N, Seeds. (All but D,

E and J from Peng et al.

21135, HAST; D, E and J from Peng et al. 20346, HAST).

414

Botanical Studies, Vol. 49, 2008

Figure 9. Begonia subcoriacea C.-I Peng, Yan Liu, S. M. Ku. A, Habitat; B, Habit; C, Rhizome; D, Stipule; E, Portion of petiole,

showing withered trichomes; F, Leaf (adaxial surface) green form; G, Leaf (adaxial surface), maculated form; H, Portion of secondary

peduncle, showing glandulose-pilose trichomes; I, Staminate flower, face view; J, Staminate flower, back view; L, Androecium; M,

Style and stigmas, arrows indicating minute protrusions between style branches; N, Fruit; O, Middle cross section of a young fruit. (A,

B from Peng et al. 21135, HAST; C-O from Peng et al. 20346, HAST).

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

415

greenish or brownish, tomentose (trichomes withered

and turning brown when old). Inflorescences axillary,

1-6, arising directly from rhizome, diffusely

cymose,

branched 3-7 times; staminate flowers 20-60, carpellate

flowers 10-32; peduncle well developed, terete, erect or

ascending, 16-35 cm long, 2-2.5 mm thick, red, covered

with reddish glandulose-pilose trichomes (trichomes 1.5-2

mm long); pedicels red, glandulose-pilose with reddish

trichomes, ascending to pendent in staminate flowers

(0.8-4.3 cm long), horizontal to pendent in carpellate

flowers (1-1.6 cm long). Bracts caducous,

oblong, margin

ciliate (lower bracts) or eciliate (upper bracts), apex acute

or obtuse, 1-10 mm long, 0.5-5 mm wide, greenish or

reddish. Staminate flowers: tepals 4, margin entire, outer

two orbicular or widely depressed ovate, base rounded or

slightly cordate, apex rounded or obtuse, 6-9 mm long,

7-10 mm wide, greenish-yellow, usually reddish toward

the base, abaxially glabrous (rarely with few glandulose-

pilose trichomes); inner two tepals obovate, base cuneate,

apex obtuse, 4-6 mm long, 3 mm wide, yellowish, gla-

brous; androecium actinomorphic,

spherical, ca. 4 mm

across; stamens ca

.

40-75,

shortly golf-club shaped;

filaments fused into a column, subequal, ca. 1.5-2.5 mm

long (free part ca. 0.5 mm, column 1.5-2 mm); anthers

2-locular, slightly compressed, obovoid, apex truncate

or slightly emarginate, 0.7-0.9 mm long, 0.5 mm wide,

yellow. Carpellate flowers: tepals 3, margin eciliate,

persistent or eventually caducous, not thickened in fruit;

outer two tepals widely depressed ovate,

6-8 mm long,

9-10 mm wide,

greenish-yellow, usually reddish toward

the base, abaxially glabrous (rarely with few glandulose-

pilose trichomes); inner tepal obovate, base cuneate, apex

rounded, ca. 5-7 mm long, 3-4.5 mm wide, yellowish,

glabrous; ovary trigonous-ellipsoid, 6-7 mm long, 4-4.5

mm across, red, glabrous (rarely with few glandulose-

pilose trichomes), 3-winged; wings unequal, greenish-

Figure 10. Mitotic chromosome spread of Begonia subcoriacea

(2n = 30, from Peng et al. 20346, HAST).

Table 2. Comparison of Begonia subcoriacea with B. liuyanii.

B. subcoriacea (Figures 8, 9)

B. liuyanii (Peng et al., 2005: Figures 1, 2)

Leaf

Size (cm)

(10-) 12-20(-22)

¡Ñ (8

-

)

10-14(-17)

(16

-)23-

38(

-50)

¡Ñ (12

-)16-

32(

-40)

Adaxial surface

Glabrous, sparsely gibbous when young; flat;

manifestly nitid

Sparsely setose; flat or slightly rugose;

weakly nitid

Abaxial surface

Tomentose on major veins, sparsely pilose on

tertiary veins

Lanuginous or tomentose throughout

Maculation on adaxial surface With or without whitish maculation in intercostal

areas

Lacking

Tertiary veins

Flat

Elevated

Quaternary veins

Obscure or not seen

Elevated

Epidermis

2-layered on both surfaces

2-layered on adaxial surface; 1-layered on

abaxial surface

Cross section

0.45-0.55 mm thick

0.2-0.33 mm thick

No. of stomatal complex /mm

2

on abaxial surface

24-30

32-65

Peduncle

Glandulose-pilose

Glandular-hispid

Inflorescence

Dichasial cymose

Thyrsoid

Outer tepals (abaxial surface) Glabrous, rarely glandulose-pilose

Glandular-hispid

Fruit

Color

Fruit body red; wings greenish-yellow, rarely

reddish

Fruit body red or reddish; wings reddish

Indumentum

Glabrous, rarely glandulose-pilose

Glandular-hispid

416

Botanical Studies, Vol. 49, 2008

Figure 11. Scanning electron microscope (SEM) micrographs of folilar trichomes and stomata complexes of Begonia subcoriacea (A,

B, C) and B. liuyanii (D, E, F). A, D, Leaf, adaxial surface; B, E, Leaf, cross section; C, F, Stomatal complexes and trichomes on leaf

abaxial surface.

PENG et al. ¡X Two new species of

Begonia

in Guangxi, China

417

yellow; lateral wings narrower, ca. 2 mm tall, glabrous;

abaxial wing crescent shaped or triangular, ca. 3-5 mm

tall, 6-7 mm wide; locule 1; placentation intruded parietal

(nearly throughout); placentae 3, each 2-branched; styles

3, fused at base (sometimes with protrusions between

style branches), yellow, ca. 3 mm long, apically split into

C-form; stigmas in a spiraled band. Fruit a dehiscent

capsule, nodding, red when fresh, 6.5-11 mm long,

5-6

mm wide (wings excluded),

apex with persistent styles;

lateral wings 2-3 mm wide;

abaxial wing crescent-shaped

or triangular, 2.5-5 mm high. Seeds many, brown, ellipsoid

or ovoid-ellipsoid, ca. 0.4-0.5 mm long,

0.27-0.3 mm

across, chalazal end rounded, micropylar end obtuse,

outer periclinal walls of mature seeds concave; collar

cells elongated, straight, nearly rectangular. Somatic

chromosome number, 2n = 30 (Figure 10).

Additional specimens examined. CHINA. Guangxi

Zhuangzu Autonomous Region, Chongzuo Shi, Daxin

Xian, Shuolong Zhen, between Longhua Cun and Rendi

Cun, elev. ca. 250 m, semishaded to shady broadleaf forest,

on N-facing limestone rock face, moist to dry, locally

frequent, associated with Tectaria devexa, Laportea,

Mallotus yunnanensis, Murraya, Pothos, Caryota

ochlandra, Ficus tinctoria ssp. gibbosa, Fissistigma,

Cipadessa cinerascens, Maesa, Piper, Smilax and tall

bamboos, 14 Mar 2005, Ching-I Peng, Yan Liu, Shin-Ming

Ku & Huan-Yu Chen 20346 (HAST).

Leaf anatomy and vestiture. Cross section 0.45-0.55

mm thick. Adaxial surface nearly glabrous (with very

sparse, minute, subsessile glands); upper epidermal cells

with flat surface; upper epidermis 2-layered, outer layer

much smaller than inner layer. Abaxial surface with

intermixed uniseriate and multiseriate trichomes on major

veins, lower epidermis 2-layered, outer layer much smaller

than inner layer. Lower stomatal complex single, nearly

flat, helicocytic, subsidiary cells 6(-7).

Ecology. Broadleaved forests; on semishady slope of

limestone hill, ca. 250 m elevation.

Etymology. The specific epithet is derived from the sub-

leathery leaves.

Distribution. Very rare; known only from a limestone

hill in southwestern Guangxi, China (Figure 4).

Phenology. Flowering March to June; fruiting May to

March next year.

Notes. Begonia subcoriacea resembles B. liuyanii in

the small flowers and the subleathery leaves, differing

by the smaller habit; leaves adaxially glabrous, abaxially

tomentose only on major veins, tertiary leaf venation flat;

outer tepals glabrous or subglabrous, and the inflorescence

dichasial cymose. Detailed comparison of salient features

of the two species is provided in Table 2.

Acknowledgments. We thank Qiner Yang (PE) for the

Latin diagnosis; Nicholas J. Turland (MO) for helpful

discussion on nomenclature; 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; Ming-Chao Yu (HAST) for the

handsome line drawings; Hai-Shan Gao (IBK), Wai-

Chao Leong, Ming-Chao Yu and Huan-Yu Chen (HAST)

for field assistance. This study was partly supported by

funding from the Personnel Training Plan of West Light

Foundation of the Chinese Academy of Sciences (2007)

to Yan Liu and grants from Academia Sinica, Taiwan and

National Geographic Society Grant # 8358-07 (Botanical

Exploration of Limestone Karsts of Southern Guangxi,

China) 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.

Gu, C.Z., C.-I Peng, and N.J. Turland. 2007. Begoniaceae. In

Z.Y. Wu, P.H. Raven, and D.Y. Hong (eds.), Flora of China,

Vol. 13. Science Press , Beijing and Mis souri Botanical

Garden Press, St. Louis, pp. 153-207.

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.

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.

Li, H.J., H. Ma, K.Y. Guan, and C.-I Peng. 2005. Begonia ru-

binea (sect. Platycentrum, Begoniaceae), a new s pecies

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.

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 s pecies 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.

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.

418

Botanical Studies, Vol. 49, 2008

Peng, C.-I, W.C. Leong, S.M. Ku, and Y. Liu. 2006b. Begonia

pulvinifera (s ect. Diploclinium, Begoniac eae), a ne w

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 s pecies from

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

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

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

limestone areas in Guangxi, China. Bot. Stud. 49: 83-92.

Shui, Y.M. and W.H. Chen. 2005. New data of sect.

Coelocentrum (Begonia) in Begoniaceae. Acta Bot. Yunnan.

27: 355-374.