Bot. Bull. Acad. Sin. (2005) 46: 83-89

PENG et al. — Begonia fangii, a new species from Guangxi, China

Begonia fangii (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China

Ching-I Peng^1,5,Yu-Min Shui^2,*, Yan Liu³, and Shin-Ming Ku^{1, 4}

¹Institute of Botany, Academia Sinica, Nankang, Taipei 115, Taiwan

²Kunming Institute of Botany, The Chinese Academy of Sciences, Kunming 650204, China

³Guangxi Institute of Botany,Guangxi Zhuangzu Autonomous Region and Academia Sinica, Guilin 541006, China

⁴Department of Life Sciences, National Cheng-Kung University, Tainan 701, Taiwan

(Received September 17, 2004; Accepted December 31, 2004)

Abstract. Begonia fangii, a new species of sect. Coelocentrum from limestone areas in southwestern Guangxi Zhuang Autonomous Region, China, is described and illustrated. Somatic chromosome number (2n = 30) is here reported. Begonia fangii is similar to B. hemsleyana (sect. Platycentrum) in having palmately compound leaves, but it is sharply distinct in having long creeping stem (vs. erect stem with a short rhizome); leaf with (3-)4-5(-7) [vs. (6-)7-10(-12)] leaflets; styles 3 (vs. 2); and ovary 1-locular with parietal placentation (vs. ovary 2-locular with axile placentation).

Keywords: Begonia fangii; Begonia hemsleyana; Begonia hemsleyana var. kwangsiensis; China; Chromosome number; Guangxi; Limestone flora; New species; Sect. Coelocentrum.

Introduction

Begonia sect. Coelocentrum comprises about 18 species in China (Guangxi, SE Yunnan and S Guizhou) and northern Vietnam (Shui et al., 2002). A number of new species were added to the list of sect. Coelocentrum thereafter (Fang et al., 2004; Ku et al., 2004). In the course of the taxonomic revision of Begonia sect. Coelocentrum, we came across several specimens that bear a superficial resemblance to B. hemsleyana Hook. f. [sect. Platycentrum] but differ markedly in having parietal placentation, a character that is diagnostic of sect. Coelocentrum. Such specimens were collected from limestone areas in SW Guangxi Zhuang Autonomous Region, which harbors many species of Begonia sect. Coelocentrum. We made several field expeditions there and were able to re-collect this remarkable species. A careful study of literature, herbarium specimens and plants grown in the experimental greenhouse reveals that it is a new species of Begonia sect. Coelocentrum.

Species Description

Begonia fangii Y. M. Shui & C.-I Peng, sp. nov.— TYPE: China. Guangxi Zhuang Autumonous Region, Chungzuo City, Longzhou Xian, Jinlong Xiang, Guiping Village, S of Yianbian Road, on the way to Banyian, 22º42'48" N,

106º47'07" E, elev. ca. 360 m. Broadleaf forest on mountain slope. On rock on steep limestone slope, shaded, abundant. Living collection made on 28 May 2004; type specimen (in flower) pressed from plant cultivated in experimental greenhouse, 14 Jan 2005. Ching-I Peng 19778A (holotype: HAST). ¤è¤ó¬î®ü´Å Figures 1, 2

Species nova similis Begoniae hemsleyanae Hook. f. (sect. Platycentrum), sed a qua caulibus longis repentibus (vs. caule erecto cum rhizomate brevi), foliis (3-)4-5(-7)-foliolatis (vs. foliis (6-)7-10(-12) foliolatis), stylis 3 (vs. stylis 2), ovario 1-loculari, placentatione parietali (vs. ovario 2-loculari, placentatione axili) differt.

Plant monoecious; epipetric; perennial. Rhizome succulent, dark purple-red, long creeping (to 50 cm or more), rooting at nodes, 8-15 mm in diameter, internodes to 8-15 cm long (1.5-3 cm at the first anthesis, elongate thereafter), covered with sparse, appressed or ascending hairs. Stipules nearly persistent, red to reddish brown, subglabrous or sparsely sericeous, triangular to narrowly triangular, asymmetric, thickly herbaceous, 12-15 mm long, 9-12 mm wide, apex subcucullate and aristate, margin entire. Leaves alternate, palmately compound; leaflets 3-6, petiolulate, subcoriaceous, dark green above, red or reddish beneath, central leaflet nearly symmetric, lateral leaflets asymmetric, lanceolate or broadly so, 7-15 cm long, 2.5-4.5 cm wide, apex acuminate, base cuneate, rounded or slightly cordate, margins entire, undulate or remotely dentate, subglabrous on upper surface, covered with appressed or slightly ascending hairs along veins on abaxial surface, venation pinnate; petiolule terete, 1-2.5 cm long, 2-2.5 mm across; petioles terete, (6-)11-15(-20) cm long, 4-5 mm across, sericeous, the hairs whitish initially, turning

⁵Current address: Research Center for Biodiversity, Academia Sinica, Nankang, Taipei 115, Taiwan. E-mail: bopeng@sinica.edu.tw

*Corresponding authors. E-mail: ymshui@mail.kib.ac.cn

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 1. Begonia fangii Y. M. Shui & C.-I Peng. A, Habit; B, Leaflet, abaxial surface; C, Portion of a leaflet, showing venation; D, Portion of leaflet, adaxial surface, D', Abaxial surface; E, Stipule, abaxial surface, E', Adaxial surface; F, Flower bud; G, Bract; H, Staminate flower, face view, H', Back view, H'', Side view; I-I'', Anther, lateral view, ventral view and dorsal view; J, Carpellate flower, face view, J', Side view; K, Style, side view, K', Top view; L, a-f, A series of cross sections of ovary; M, Capsule. (All but M from a living plant (Leong 3374) cultivated in the experimental greenhouse; M from Peng 19769 (HAST). Line drawing by Shin-Ming Ku).

PENG et al. — Begonia fangii, a new species from Guangxi, China

Figure 2. Begonia fangii Y. M. Shui & C.-I Peng. A, Habit and habitat; B, A cultivated plant at early anthesis, showing long creeping stem; C, Flowers, staminate (right) and carpellate (left); D, Carpellate flower; E, Cross section of ovary, showing parietal placentation; E, Fruit. (A, F from Peng 19769 (HAST); B, C, D, E from a living plant (Leong 3374) cultivated in the experimental greenhouse. Photos A, F by Ching-I Peng; B by Mao-Lun Weng; C, D, E by Shin-Ming Ku).

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

brownish. Inflorescence an axillary dichasial cyme; peduncle well developed, reddish to red-brown, to 22 cm long, 2.5-3 mm in diameter, erect, sparsely to moderately pubescent, the hairs ascending, straight or curly; pedicels reddish to brownish, erect to ascending in staminate flowers, ascending to horizontal in carpellate flowers, sparsely pubescent. Bracts caducous, glabrous or rarely sparsely hairy on abaxial surface, oblong to ovate, herbaceous, greenish with reddish nerves, 8-13 mm long, 6-9 mm wide, apex acute to obtuse, margin loosely ciliate-serrate on upper part, entire below. Tepals pinkish. Staminate flowers: tepals 4, outer two broadly ovate to orbicular, apex rounded, base slightly cordate, 16-27 mm long, 20-24 mm wide, pilose on abaxial surface (denser toward base), the hairs whitish, more or less curved; inner two obovate, oblanceolate to obtrullate, 11-12 mm long, ca. 7 mm wide, glabrous; androecium zygomorphic, compressed; stamens 25-55, golf-club shaped, yellow; filaments free, subequal, 1.5-2 mm long; anthers oblong, yellow, to 1.5-1.7 mm long. Carpellate flowers: tepals 3, caducous, outer two broadly ovate to orbicular, apex rounded, base slightly cordate, 13-15 mm long, 14-16 mm wide, sparsely pilose on abaxial surface; inner one 8-10 mm long, ca. 5 mm wide, glabrous; ovary sparsely pilose or subglabrous, pinkish, 3-winged; wings unequal or subunequal; lateral wings ca. 3-4 mm high, 8-10 mm wide; abaxial wing semi-orbicular, 3.5-4 mm long, 8-10 mm wide; locule 1 with 3 parietal placentae, each biforked, T-shaped, rarely branched again; styles 3, yellowish, ca. 3.5 mm long, fused in the lower 1/5; stigma bands U-shaped, slightly spiraled. Fruit a dehiscent capsule, nodding, 12-15 mm long, 6-7 mm wide (not including wings), very sparsely pilose to glabrous; lateral wings 4-5 mm high, 12-15 mm wide; abaxial wing 4-6 mm high, 12-15 mm wide. Seeds many, brown, ellipsoid, 0.5-0.6 mm long, 0.3-0.35 mm in diam. Somatic chromosome number, 2n = 30 (Figure 3).

Paratypes. CHINA. Guangxi Zhuang Autonomous Region: Nanning, specimen made from plants in cultivation at Guangxi Botanical Garden, 16 Mar 1981, Ni & Lu 8988 (GXMG). Longzhou Xian, Jinlong Xiang, Banbi, Paotaishan, 21 Apr 1956, Lee 95 (IBK, IBSC); same locality, elev. 600-700 m, 19 Apr 1990, Fang & Yan 76371 (GXMI); same locality, elev. 450 m, 26 Apr 1991, Qin 80226 (GXMI); Longzhou Xian, Jinlong People's Commune, Gaoshan Dadui, Banbi, Yahuai, 7 Feb 1977, Fang & Tao 76184 (GXMI); Longzhou Xian, Jinlong Xiang, Gaoshan Village, 250 m alt., in remote forest on limestone hills, 15 Sep 2003, Shui et al. B2003-46 (KUN); Chungzuo City, Longzhou Xian, Jinlong Xiang, Guiping Village, S of Yianbian Road, on the way to Banyian, 22°42'48" N, 106°47'07" E, elev. ca. 360 m. Broadleaf forest on mountain slope. On rock on steep limestone slope, shaded. Plant sterile when collected, leaves green above, red beneath. 28 May 2004, Peng 19778 (HAST); Chungzuo City, Longzhou Xian, Jinlong Xiang, Banyian, 22°42'48" N, 106°47'07" E, ca. 400 m. Scrubby vegetation on mountain slope. Frequent on semi-shaded limestone rock face, 28 May 2004, Peng 19790 (HAST); Nanning Diqu, Longzhou Xian, Jinlong Zhen, Gaoshan Cun, Banbi Tun, Guipi Shan, 22°43'59" N, 106°45'42" E, elev. ca. 550 m, 30 Aug 2002, Leong 3374 (HAST), 3374A (HAST, flowering specimen pressed from plant in cultivation, 2 Feb 2004).

Ecology. Creeping up limestone rock face on semi-exposed or shady forested slope, at 250-700 m altitude.

Distribution. Guangxi, China (Figure 4); possibly also in northern Vietnam.

Phenology. Flowering December to March; fruiting March to June.

Etymology. The specific epithet commemorates Prof. Ding Fang, Guangxi Institute of Traditional Medical and

Figure 3. Mitotic chromosome spread of Begonia fangii (2n = 30, from Leong 3374, HAST).

Figure 4. Distribution of Begonia fangii (star) in Guangxi Zhuang Autonomous Region, China.

PENG et al. — Begonia fangii, a new species from Guangxi, China

We have ruled out the possibility that our new species is Begonia hemsleyana var. kwangsiensis Irmsch., an imperfectly known taxon represented by only one collection made in 1928. A study of the original protologue (Irmscher, 1939) and isotypes of B. hemsleyana var. kwangsiensis [China, Guangxi ("Kwangsi"), Tsin Lung ("Hung") Shan, N. Lin Yen in deep ravine, 4000 ft., 14 Aug 1928, R.C. Ching 6921 (IBSC; PE: Figure 6)] confirmed that Begonia fangii is distinct from that variety, which has membranous leaves, leaflets with cleft margin and attenuate or subsessile bases, glabrous petioles, an erect stem with a short rhizome, and a protruded abaxial wing on the capsule.

Acknowlegments. We thank Dr. Qiner Yang (PE) for assistance with the Latin diagnosis; Mr. Wai-Chao Leong (HAST) and Ms. Wen-Hong Chen (KUN) for field assistance; Mr. Mao-Lun Weng (HAST) for taking handsome photographs of Begonia fangii in cultivation; Curators of GXMG, GXMI, IBK, IBSC, KUN and PE for facilitating our examination of herbarium collections. The authors are grateful to Dr. Thomas G. Lammers for useful comments on the manuscript. This study was supported in part by grants from National Science Council and Academia Sinica, Taiwan to Dr. Ching-I Peng (HAST) and from National Natural Science Foundation of China (grant no. 30270109) to Dr. Yu-Min Shui (KUN).

Literature Cited

Fang, D., Y. G. Wei, and D.H. Qin. 2004. Four new species of Begonia L. (Begoniaceae) from Guangxi, China. Acta Phytotax. Sin. 42(2): 170-179.

Irmscher, E. 1939. Die Begoniaceen Chinas und ihre Bedeutung für die Frage der Formbildung in polymorphen Sippen. Mitt. Inst. Allg. Bot. Hamburg 10: 431-557.

Ku, T.C. 1999. Begoniaceae. In T. C. Ku (ed.), Flora Reipublicae Popularis Sinicae, vol. 52 (1). Science Press, Beijing, pp. 126-269, Addenda, pp. 401-402.

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.

Nakata, M. K. Guan, T. Godo, Y. Lu, and J. Li. 2003. Cytologi

Figure 5. SEM microphotographs of Begonia seeds. A, Begonia fangii (from Leong 3374, HAST); B, Begonia hemsleyana (from Peng 18680, HAST).

Pharmaceutical Sciences, Nanning, China, for his contribution to our knowledge of flora of Guangxi.

Notes. Begonia fangii is a very distinctive member of sect. Coelocentrum, which is characterized mainly by parietal placentation. This new species is epipetric, occurring in limestone areas in SW Guangxi Zhuang Autonomous Region at the China-Vietnam border. It bears a superficial resemblance to Begonia hemsleyana Hook. f., which is a relatively widespread terrestrial species in China (Yunnan, Guangxi, and Sichuan provinces) (Ku, 1999) and northern Vietnam [Ha Giang Prov., Peng 20155, 20157, 20158, 20204 (all at HAST)]. Previously, Begonia hemsleyana was known as the only species of Begonia with palmately compound leaves (Ye et al., 2004: Figure 3) in the Old World (Irmscher, 1939). Begonia fangii is the second species with such a character. However, B. hemsleyana belongs to sect. Platycentrum, which is characterized by axile placentation with 2-locular ovary. Table 1 summarizes salient distinctions between B. fangii and B. hemsleyana.

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 6. Isotype of Begonia hemsleyana var. kwangsiensis (PE).

PENG et al. — Begonia fangii, a new species from Guangxi, China

cal studies on Chinese Begonia (Begoniaceae) I. Chromosome numbers of 17 taxa of Begonia collected in 2001 field studies in Yunnan. Bull. Bot. Gard. Toyama 8: 1-16.

Shui, Y. M., C.-I Peng, and C.Y. Wu. 2002. Synopsis of the Chinese species of Begonia (Begoniaceae), with a reappraisal of sectional delimitation. Bot. Bull. Acad. Sin. 43: 313-327.

Tien, D.K., K.Y. Guan, Q.X. Zhou, and Z.J. Gu. 2002. Chromosome numbers of eight taxa of Begonia from Yunnan. Acta Bot. Yunnan. 24: 245-249.

Ye, H.G., F.G. Wang, Y.S. Ye, and C.-I Peng. 2004. Begonia coptidifolia (Begoniaceae), a new species from China. Bot. Bull. Acad. Sin. 45: 259-266.