Bot. Bull. Acad. Sin. (2005) 46: 245-254

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

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

Ching-I PENG^1,*, Shin-Ming KU^{1, 2}, and Wai-Chao LEONG¹

¹Herbarium, Research Center for Biodiversity, Academia Sinica, Nangang, Taipei 115, Taiwan

²Department of Life Sciences, National Cheng-Kung University, Tainan 701, Taiwan

(Received January 4, 2005; Accepted May 31, 2005)

Abstract. Begonia liuyanii, a new species of sect. Coelocentrum from limestone areas in southwestern Guangxi Zhuang Autonomous Region, China, is described and illustrated. A somatic chromosome number of 2n = 30 was determined. Begonia liuyanii is similar to B. filiformis in having small flowers and glandular-hispid inflorescences but is distinguishable by its larger leaves (16-38 × 12-32 cm vs. 9-22 × 9-14 cm), sparsely setose (vs. tomentose) upper surface of the leaves, maculation absent (vs. with white maculation in intercostal area on adaxial leaf surface), and usually thyrsoid (vs. cymose) inflorescence.

Keywords: Begonia filiformis; Begonia liuyanii; Begonia masoniana; Begoniaceae; China; Chromosome number; Guangxi; Limestone flora; New species; Rare species; sect. Coelocentrum.

Introduction

Towards a taxonomic revision of Chinese Begonia, we have made many field expeditions in recent years. Our surveys have resulted in the discovery of a number of new species, e.g., B. coptidifolia H. G. Ye, F. G. Wang, Y. S. Ye & C.-I Peng (Ye et al., 2004), B. curvicarpa S. M. Ku, C.-I Peng & Yan Liu and B. luochengensis S. M. Ku, C.-I Peng & Yan Liu (Ku et al., 2004) and B. fangii Y. M. Shui & C.-I Peng (Peng et al., 2005). Tropical limestone areas are rich in species and, in a taxonomic sense, are among the least studied types of habitat in the world (Wong et al., 2003). In southern China, all the species of Begonia sect. Coelocentrum Irmsch. grow on limestone between 300 and 1,300 m elevation (Shui et al., 2002). In this paper we report the discovery of yet another new species in sect. Coelocentrum, B. liuyanii C.-I Peng, S. M. Ku & W. C. Leong, from southwestern Guangxi Zhuang Autonomous Region, an area noted for its karst landscape and cave systems. A careful study of the literature, herbarium specimens and plants, both in the wild and in cultivation in the experimental greenhouse, reveals that B. liuyanii is sharply distinct from such congeners as B. filiformis Irmsch. and B. masoniana Irmsch. ex Ziesenh.

Species Description

Begonia liuyanii C.-I Peng, S. M. Ku & W. C. Leong, sp. nov.—TYPE: China. Guangxi Zhuang Autonomous Region, Longzhou Xian, Jinlong Zhen, Nonggang Nature Reserve, 22°28'34" N, 106°54'17" E, elev. ca. 200 m, broadleaved forest on mountain slope, 12 Sep 2003;

type specimen pressed from plant cultivated in an experimental greenhouse, Wai-Chao Leong 3624-A (holotype: HAST; isotypes: A, IBK). ¼Bºt¬î®ü´Å Figures 1, 2, 3

B. filiformi similis ob sed floribus parvis et inflorescentiis glanduloso-hispidis, foliis majoribus (16-38 × 12-32 cm vs. 9-22 × 9-14 cm), supra sparse setosis (vs. tomentosis), haud maculatis (vs. supra inter costas albo-maculatis) differt.

Plant monoecious; epipetric; perennial; rhizomatous. Rhizome stout, 10-20 cm long, 1-2.5 cm thick, internodes 0.8-1.3 cm long, brown, villous when young, glabrate when old, with few white, prominently raised, sometimes spine-like, small protrusions. Stipules caducous, narrowly triangular (rarely oblong ovate with apex obtuse), ca. 2-2.5 cm long, 1-1.3 cm wide, brownish, herbaceous, abaxially lanulose-villous, margin ciliate, weakly to strongly keeled, apex aristate, arista 5-7 mm long, horn-like. Leaves 2-5, alternate, simple, asymmetric, unlobed, widely ovate or suborbicular, base strongly oblique-cordate, margin inconspicuously irregularly repandly denticulate and shortly ciliate, apex shortly acuminate, 23-38 cm long (basal lobes included), 16-32 cm wide, adaxially green or dark green, abaxially pale (reddish when young), lacking maculation, subcoriaceous, surface somewhat nitid, flat or somewhat rugose, adaxially sparsely setose (trichomes conical or needle-like with base slightly swollen, nearly erect, straight or slightly curved at apex, 0.5-1 mm long, whitish-hyaline), abaxially lanuginous, particularly pronounced on veins; venation basally 6-7-palmate, midrib distinguishable, pinnate along midrib, with 1-3 major lateral veins on each side, other primary veins dichotomously branching or nearly so, tertiary veins percurrent or reticulate, divergence angle 60-85°, minor veins reticulate, all veins on abaxial surface prominently raised; petiole terete, 13-22 cm long, 5-10 mm

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

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 1. Begonia liuyanii C.-I Peng, S. M. Ku & W. C. Leong. A, Habit. B, Stipule, triangular, apex with horn-like arista, abaxial surface; B', adaxial surface; B'', lateral view. C, Stipule, oblong ovate with obtuse apex, abaxial surface; C', adaxial surface. D, Bract at first node of inflorescence; D', at summit of inflorescence. E, Portion of glandular-hispid peduncle. F, Staminate flower, face view; F', back view. G, Stamen, dorsal view; G', ventral view. H, Carpellate flower, face view; H', lateral view. I, Fruit with crescent-shaped abaxial wing; I', fruit with triangular abaxial wing. J: a-e, Serial cross sections of immature fruit. K, Seeds. (All but F, F' and I' from a living plant (Peng 18820, HAST) cultivated in the experimental greenhouse; F, F' and I' from Leong 3624 (HAST).

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

Figure 2. Begonia liuyanii C.-I Peng, S. M. Ku & W. C. Leong. A, Habitat, showing a population of B. liuyanii (Leong 3624, HAST) on rocky limestone slope in broadleaved forest. B, Habit, showing a fruiting individual (Leong 3398, HAST).

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 3. Begonia liuyanii C.-I Peng, S. M. Ku & W. C. Leong. A, Inflorescence diffusely thyrsoid. B, Leaf, adaxial surface showing setae. C, Leaf, lanulose abaxial surface. D, Stipule. E-G, Carpellate flowers. H-I, Staminate flower. J, Seed SEM microphotograph. K, Fruit. L, Middle cross section of an immature fruit showing parietal placentation. (A, D-G, I, J, L from Peng 18820; B, C, H, from Leong 3398; K from Leong 3624. All at HAST).

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

thick, brown, villous or lanuginous. Inflorescences axillary, 1-3, arising directly from rhizomes, diffusely thyrsoid (rarely cymose), branched 3-6 times; staminate flowers 10-30, carpellate flowers 3-20; peduncle well developed, terete, erect, 20-41 cm long, 2-5 mm thick, sanguineous, covered with sanguineous glandular-hispid trichomes (trichomes 1.5-1.8 mm long); pedicels sanguineous, glandular-hispid with sanguineous trichomes, ascending to pendent in staminate flowers (0.7-1.2 cm long), horizontal to pendent in carpellate flowers (1.5-2.5 cm long). Bracts caducous, ovate or oblong, margin glandular-ciliate or entire, apex acute, 1-3 mm long, 1-2.5 mm wide, greenish or reddish, herbaceous. Staminate flowers: tepals 4, margin entire, outer two orbicular or widely depressed ovate, base rounded or slightly cordate, apex rounded or obtuse, rarely acute, 7-9 mm long, 8-9 mm wide, abaxially yellowish, greenish yellow or reddish, adaxially whitish, yellowish or sometimes reddish, abaxial surface sparsely red glandular-hispid; inner two tepals obovate, oblong or lanceolate, base cuneate, apex acute, acuminate or obtuse, ca. 5-6 mm long, 3 mm wide, whitish or yellowish, glabrous; androecium actinomorphic, spherical, stamens ca. 30-40, shortly golf-club shaped; filaments slightly fused at base, subequal, ca. 0.4-0.5 mm long; anthers 2-locular, slightly compressed, obovoid, apex truncate or slightly emarginate, ca. 0.6-0.7 mm long, 0.45 mm wide, yellowish. Carpellate flowers: tepals 3, margin entire, persistent, slightly thickened in fruit; outer two tepals widely depressed ovate, 5-7 mm long, 6-7 mm wide, yellowish or reddish, abaxially sparsely red glandular-hispid; inner tepal obovate, base cuneate, apex rounded, ca. 3 mm long, 2 mm wide, yellowish, glabrous; ovary trigonous-ellipsoid, 5-7 mm long, 4-4.5 mm across, reddish, red glandular-hispid, 3-winged; wings unequal; lateral wings narrower, ca. 1-2 mm high, red glandular-hispid; abaxial wing crescent shaped or triangular, ca. 3-7 mm high, 5-7 mm wide; locule 1; placentation intruded parietal (axile near base); placentae 3, each 2-branched; styles 3, fused at base, yellow, ca. 1.5 mm long, apically split into C-form; stigmas in a spiraled band. Fruit dehiscent capsules, nodding, reddish when fresh, 8-11 mm long, 5 mm wide (wings excluded), apex with persistent styles; lateral wings 2-4 mm high; abaxial wing crescent-shaped or triangular, 4-10 mm high. Seeds many, brown, usually widely ovoid-ellipsoid, sometimes ellipsoid, (0.35-) 0.4-0.47 mm long, 0.25-0.3 mm across, chalazal end rounded, micropylar end obtuse, outer periclinal walls of mature seeds concave; collar cells elongated, straight, nearly rectangular, 12-15 cells in a ring, occupying 1/3 -1/2(-2/3) of seed length; anticlinal walls between collar cells raised, straight or slightly undulate; testa cell nearly isodiametric-polygonal. Somatic chromosome number, 2n = 30 (Figure 4).

Additional specimens examined. CHINA. Guangxi Zhuang Autonomous Region, Longzhou Xian, Shanglong Xiang, from Banhua to Nonggang Nature Protected Area, ca. 10 km from the entrance of the Area, 22°29'19" N, 106°54'26" E, elev. ca. 200 m, 31 Aug 2002, Wai-Chao Leong 3398 (HAST), 3398-A (HAST, flowering specimen pressed from a plant in cultivation, 24 May 2005); Guangxi

Figure 4. Mitotic chromosome spread of Begonia liuyanii (2n= 30, from Leong 3624, HAST).

Zhuang Autonomous Region, Longzhou Xian, Jinlong Zhen, Nonggang Nature Reserve, 22°28'34" N, 106°54'17" E, elev. ca. 200 m, broadleaf forest on mountain slopes, 12 Sep 2003, Wai-Chao Leong 3624 (HAST); Guangxi Zhuang Autonomous Region, Longzhou Xian, Shanglong Xiang, Xinliang Cun, 23°29'19" N, 106°54'24" E, elev. ca. 200 m, 6 Mar 2005, Ching-I Peng 20388 (HAST). Guangxi Zhuang Autonomous Region, exact locality unknown, specimen pressed from a living collection presented by Yan Liu, 2 Jun 2002, Ching-I Peng 18820 (HAST).

Ecology. Broadleaved forests; on shaded, rocky limestone slopes, ca. 200 m elevation.

Etymology. The specific epithet commemorates Mr. Yan Liu, Curator of the IBK Herbarium, Guangxi Institute of Botany, a keen botanist who first collected this rare species and who accompanied us on a number of field expeditions in Guangxi Zhuang Autonomous Region, China.

Distribution. Southwestern Guangxi, China (Figure 5).

Figure 5. Distribution of Begonia liuyanii (star), B. filiformis (solid circle) and B. masoniana (open circle) in Guangxi Zhuang Autonomous Region, China.

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 6. Holotype of Begonia filiformis Irmsch. (Morse 575, K), inset (middle left) showing a staminate flower in fragment packet.

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

Figure 7. Begonia filiformis Irmsch. A, Habitat and habit, showing plants on limestone face. B, Cultivated plant in Kunming Botanical Garden, Yunnan. C, Portion of tomentose leaf. D, Inflorescence at early phase of flowering. E, Carpellate flower bud. F, G, Carpellate flowers. H, Middle cross section of an ovary. (A, C-E, from Peng 20332, HAST; B, F-H, from Hong-Zhe Li HZ-051, KUN)

Botanical Bulletin of Academia Sinica, Vol. 46, 2005

Figure 8. Begonia masoniana Irmsch. ex Ziesenh. A, Habitat and habit showing fruiting plant on limestone. B, Habit, showing plant at late anthesis. C, Portion of leaf showing bullate surface and trichomes. D, Stipule strongly keeled with horn-like appendage. E, Inflorescence. F, Staminate flower, back view. G, Staminate flower, face view. H, Carpellate flower, side view. I, Carpellate flower, face view. J, Middle cross section of an ovary. K, Seed SEM microphotograph. (A from Peng 19795, B from Leong 3658-A, C-K from Leong 3658; all at HAST)

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

Phenology. Flowering April to August (rarely to September); fruiting May to September.

Notes. Among the two dozen or so congeners in Begonia sect. Coelocentrum, B. liuyanii (Figures 1, 2, 3) shares with B. filiformis (Figures 6, 7) and B. masoniana (Figure 8) characteristically small flowers and actinomorphic androecia. A comparison of their salient features is shown in Table 1. All three species occur allopatrically in southwestern Guangxi (Figure 5). They are all rare species, known only from very few collections. Important morphological characters of Begonia do not usually preserve well in herbarium specimens. Colored images of all three species are provided to aid in identification.

Acknowledgments. We thank Qiner Yang (PE) for his assistance with the Latin diagnosis; Yan Liu (IBK) and Huan-Yu Chen (HAST) for field assistance; Hong-Zhe Li (KUN), Chien-I Huang, Mao-Lun Weng (HAST) and Wei-Hsin Hu (TNM) for providing handsome images (Hu: Figure 3: J; Huang, Figure 7: B; Li, Figures 7: F-H; Weng: Figures 3: A, 8: E) and the curators of IBK, K and KUN for facilitating our examination of herbarium collections. We are grateful to David E. Boufford, Bruce Bartholomew and Thomas Lammers for useful comments on the manuscript. This study was supported in part by grants from the Research Center for Biodiversity, Academia Sinica, Taiwan, to Ching-I Peng (HAST).

Literature Cited

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.

Peng, C.-I, Y. M. Shui, Y. Liu, and S.M. Ku. 2005. Begonia fangii (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China. Bot. Bull. Acad. Sin. 46: 83-89.

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.

Wong, T., E. Hamilton-Smith, S. Chape, and H. Friederich (eds.). 2003. Proceedings of the Asia-Pacific Forum on Karst Ecosystems and World Heritage. 26-30 May 2001, Gunung Mulu Natl. Park World Heritage Area, Sarawak, Malaysia. IUCN, Gland, Switzerland.

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.

Botanical Bulletin of Academia Sinica, Vol. 46, 2005