Bot. Bull. Acad. Sin. (2004) 45: 259-266

Ye et al. — Begonia coptidifolia, a new species from China

Begonia coptidifolia (Begoniaceae), a new species from China

Hua-Gu YE¹, Fa-Guo WANG¹, Yu-Shi YE¹, and Ching-I PENG^2,*

¹South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou, Guangdong 510650, China

²Institute of Botany, Academia Sinica, Nankang, Taipei 115, Taiwan

(Received July 4 2003; Accepted June 29, 2004)

Abstract. Begonia coptidifolia H. G. Ye, F. G. Wang, Y. S. Ye & C.-I Peng, a new species from Guangdong province, China, is here described and illustrated. Its chromosome number (2n=22) and karyotype are reported. Begonia coptidifolia belongs to sect. Platycentrum and somewhat resembles B. hemsleyana Hook. f., from which it differs by the aerial stems seen only at anthesis (vs. all year round), palmately trisected leaves with pinnately parted lobules (vs. leaves palmately compound with 7-9 petiolulate leaflets) and petioles grooved on adaxial surface (vs. terete). The new species also resembles Begonia pedatifida H. Lév., which, however, has much stouter rhizomes (2-6 cm vs. 0.3-0.5 cm thick), leaves palmatifid with triangular lobules, and terete petioles. Begonia coptidifolia is rare, known only from a small ravine in Ehuangzhang Nature Reserve, Yangchun, Guangdong Province.

Key words: Begoniaceae; Begonia coptidifolia; Begonia hemsleyana; Begonia pedatifida; China; chromosome number; Ehuangzhang Natural Reserve; Guangdong; karyotype; new species; rare species.

Introduction

Begonia L. is a large genus of about 1,400 species widely distributed in tropical and subtropical areas, especially in Central and South America (Smith et al., 1986; Doorenbos et al, 1998). About 150 species of Begonia are indigenous to China, mainly south of the Yangtze River. The distribution center of Chinese Begonia is from southeastern Yunnan to southwestern Guangxi (Ku, 1999; Shui et al., 2002; Tian et al., 2002). Shui et al. (2002) in a synopsis of Chinese Begonia, divided the Chinese species into nine sections.

Sect. Platycentrum (Klotzsch) A. DC. consists of about 110 species that range from India through central China to southeastern Asia. In China, 63 species have been reported from south of Yangtze River, from SE Xizang to Taiwan (Shui et al., 2002).

The Ehuangzhang Natural Reserve lies in Yangchun city in southeastern Guangdong Province, China. It occupies an area of about 15,000 ha, between 21°50'36" and 21°58'40"N and 111°21'29" and 111°36'03"E, and ranges from 50 to 1337.6 m in elevation. It is covered by natural forests and is an important area for biodiversity conservation (Wang et al., 2004a; Wang et al., 2004b). During botanical expeditions to the Ehuangzhang Natural Reserve in 2001-2002, we recorded 1,415 species in 726 genera of vascular plants, including four species of Begonia: B. fimbristipula, B. leprosa, B. palmata and the new species Begonia coptidifolia, which is described and illustrated here.

Species Description

Begonia coptidifolia H. G. Ye, F. G. Wang, Y. S. Ye & C.-I Peng, sp. nov. — TYPE: China. Guangdong: Yangchun city, Ehuangzhang Natural Reserve, Honghuatan, alt. ca. 600 m, in a ravine, on rocks at streamside, 8 Sep 2002, Hua-Gu Ye 7535 (holotype, IBSC; isotypes, HAST, IBSC). Figures 1-2

Haec species affinis B. hemsleyana Hook. f., sed folio palmatim trisecto, lobis pinnatifidis, stipulis longi-triangulatis, bracteis angusti-trianglatis distinguitur.

Plants monoecious, rhizomatous, internodes short, indistinct, rooting at nodes. Rhizomes slender and short, unbranched, covered with stipules. Stipules brown, membranaceous, glabrous, persistent, triangular, 5-8 × 3-4 mm, margins entire, apex long cuspidate. Erect stem absent when sterile; stem at anthesis 10-15(-30) cm long, unbranched, subtended by 1-3 leaves. Basal leaves 2-5; petiole 5-13 cm, adaxial surface grooved, sparsely setulose; blade ovate to suborbicular in outline, 10-18 × 8-15 cm, palmately 3-cleft to base, sparsely setulose on upper surface and along midvein and secondary veins on lower surface; lobes ovate-lanceolate, 2.7-10.2 × 1.4-4.1 cm, often 2-cleft again to base; lobules narrowly elliptic-lanceolate, 3-9 × 1.5-3.5 cm, pinnately parted; segments oblong-lanceolate, 1.4-5.1 × 0.4-1.1 cm, apex acute, with 2-4 teeth on each side; cauline leaves smaller than basal leaves. Inflorescence axis 5-15 cm, glabrous. Inflorescence a terminal cyme, flowers 1-4; bract narrowly triangular, 10 × 3 mm, apex acute. Peduncle 3.5-4(-7) cm long at fruiting. Staminate flower: pedicel 13 mm long, white; tepals 4, in two whorls, outer two broadly ovate, ca. 12 × 13 mm, base slightly cordate, apex rounded; inner two ovate, ca. 12 × 8 mm; stamens many, filaments fused below into a column.

*Corresponding author. Tel: +886-2-2789-3821; Fax: +886-2-2789-1623; E-mail: bopeng@sinica.edu.tw

Botanical Bulletin of Academia Sinica, Vol. 45, 2004

Figure 1. Begonia coptidifolia H. G. Ye, F. G. Wang, Y. S. Ye & C.-I Peng. A, Habit; B, Staminate flower, face view, B', Lateral view; C, Carpellate flower; D, Style; E, Capsule; F, Cross section of fruit, G, Stipule, abaxial surface, G', adaxial surface; H, Segment of lobule, abaxial surface, H', adaxial surface, I, Hispidulous abaxial surface of lobule; J, Cross-section of leaf petiole. (All but B' and G-J from Hua-Gu Ye 7535, line drawing by Yun-Xiao Liu; B', G-J from Peng 19456, line drawing by Shin-Ming Ku)

Ye et al. — Begonia coptidifolia, a new species from China

Figure 2. Begonia coptidifolia H.G. Ye, F.G. Wang, Y.S. Ye & C.-I Peng. A, habit, bar = 5 cm; B (inset), staminate flower, bar = 1 cm; C, aerial stem with maturing capsules, bar = 5 cm; D (inset), capsule, bar = 1 cm. All from Peng 19456. (Photos by Ching-I Peng)

Botanical Bulletin of Academia Sinica, Vol. 45, 2004

Figure 3. Begonia hemsleyana Hook. f. A, Habit; B, Leaflet, abaxial surface; C, Segment of leaflet, adaxial surface, C', abaxial surface; D, Stipule, abaxial surface, D', adaxial surface, D'', lateral view; E, Bract, abaxial surface, E', adaxial surface; F, Staminate flower; G, Carpellate flower; H, Capsule; I, Cross section of ovary. All from Peng 18681 (HAST) (Line drawing by Shin-Ming Ku)

Ye et al. — Begonia coptidifolia, a new species from China

Figure 4. Begonia pedatifida H. Lév. A, Leaf; B, Flowering shoot; C, Segment of leaf, adaxial surface, C', abaxial surface; D, Staminate flower; E, Androecium; F, Stamen; G, Tepals of carpellate flower; H, Stigma, dorsal view, H', ventral view; I, Cross section of ovary. All from Shui 9014 (HAST). (Line drawing by Ya-Wen Hsue)

Botanical Bulletin of Academia Sinica, Vol. 45, 2004

Carpellate flowers: pedicel pinkish white, 14-17 mm long, sparsely hispidulous; tepals 5, white, ovate, ca. 10 × 7 mm, apex rounded; ovary obovate-trigonous, 2-locular. Capsule obovate-oblong, ca. 2.5 cm long, 1.3-1.6 cm in diam.; wings 3, unequal, larger one ligulate, 1.7-2.3 cm, apex obtuse, glabrous, other two narrower, ca. 8 mm long, sparsely hairy.

Paratypes. China. Guangdong province: Yangchun city, Ehuangzhang mountain, Honghuatan, alt. ca. 600 m, in a ravine, on rocks at streamside. 10 Nov 2002, Hua-Gu Ye s.n. (IBSC); 3 Nov 2003, Ching-I Peng 19456 (HAST).

Ecology. Begonia coptidifolia grows on moist, mossy rocks along streams in evergreen forests on a granite mountain at about 600 m elevation.

Distribution. Known only from the type locality.

Phenology. Flowering Jul to Sep; fruiting Oct to Dec.

Etymology. This unique species of Begonia has the leaves palmately divided and the lobes pinnately parted again like those of Coptis chinensis Franch. The specific epithet is derived from Coptis and folium.

Note. Begonia coptidifolia somewhat resembles Begonia hemsleyana Hook. f. (Figure 3) and Begonia pedatifida H. Lév. (Figure 4). Table 1 shows some of the salient differences among the three species.

Chromosome Cytology. Begonia coptidifolia has a somatic chromosome number of 2n = 22 (Figure 5), which is similar to a number of other members of Begonia Sect. Platycentrum (Oginuma and Peng, 2002; Shui et al., 2002; Tian et al., 2002; Nakata et al., 2003; Peng et al., unpublished data) in China. Length and arm ratio of each pair of chromosomes are listed in Table 2. The chromosomes are small, ranging from 1.36 to 5.43 mm in length. The positions of centromeres of chromosome pairs 9 and 11 are not

Figure 5. Karyomorphology of Begonia coptidifolia. A, Somatic chromosomes at metaphase, 2n = 22. B, Karyotype: chromosomes pairs arranged by decreasing order of length, dots indicating positions of centromeres. (From Peng 19456)

Ye et al. — Begonia coptidifolia, a new species from China

discernible. All other chromosomes are metacentric, basing on the classification categories of Levan et al. (1964). Chromosome arm ratios (long/short) range from 1.33 to
2.70. Chromosome pairs 9, 10 and 11 are much smaller than the rest of the complement.

Acknowledgments. This work was supported in part by a special grant from the Chinese Academy of Sciences (STZ-00-20) and the Heweishan Forestry Bureau, Yangchun City, Guangdong Province to Hua-Gu Ye and a research grant from National Science Council, Executive Yuan, Taipei, Taiwan, to Ching-I Peng. We thank Yun-Fei Deng and Shin-Ming Ku for technical assistance with the manuscript; Shi Huang and Wai-Chao Leong for help in the field; Mei-Chu Chung for interpreting the chromosome cytology of Begonia coptidifolia; Yun-Xiao Liu, Ya-Wen Hsue, and Shin-Ming Ku for the handsome line drawings. We are grateful to David E. Boufford for careful review of the manuscript.

Literature Cited

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Botanical Bulletin of Academia Sinica, Vol. 45, 2004