Begonia calciphila, Peng, Ching-I, Yang, Hsun-An, Kono, Yoshiko, Jung, Ming-Jer & Nguyen, Tien Hiep, 2015

Peng, Ching-I, Yang, Hsun-An, Kono, Yoshiko, Jung, Ming-Jer & Nguyen, Tien Hiep, 2015, Four new species of Begonia (Begoniaceae) from Vietnam: B. abbreviata, B. calciphila, B. sphenantheroides and B. tamdaoensis, Phytotaxa 222 (2), pp. 83-99 : 89-92

2. Begonia calciphila C.-I Peng, sp. nov. (sect. Coelocentrum ) ( Figs 6 , 7 )

Type: — VIETNAM. Ninh Binh Province, Nho Quan District, Cuc Phuong National Park, near Khu Thung Tam Park Center (previously Bong Village ), 20°21’01”N, 105°35’38”E, elev. ca. 400 m. On surface of steep limestone rocky slope in broadleaf forest, semishaded, occasional. Sterile plants collected on 18 Nov 2004 ; type specimen (with flowers) pressed from plants cultivated in the experimental greenhouse, 16 Feb 2011. Ching-I Peng, Wai-Chao Leong, Shin-Ming Ku, Nguyen Tien Hiep & Mai Van Sinh 20226 (holotype: HAST 139793 ; isotypes: A, CAS, E, K, KEP, HN, MO, P) Îñkȁầ

Begonia semicava Irmsch. , in sched.

Herbs perennial, monoecious, lithophytic. Rhizomes creeping, to 30 cm or longer, internodes 1.5–4.5 cm long, 6–8 mm across, reddish or whitish hirsute, hairs 3–3.5 mm long, glabrescent. Stipules ovate, 7–12 mm long, 4–7 mm wide, apex caudate, margin entire, abaxially hirsute, hairs 1.5–3.5 mm long. Leaves alternate; petiole brownish, 2–7 cm long, villous, hairs 3.5–4 mm long, brownish or reddish; leaf blade orbicular-ovate to ovate, apex acute, base obliquely cordate, 7–10.5 cm long, 5.5–8.5 cm wide, margin undulate, densely ciliate; primary veins 6–8, palmate, veinlets reticulate; adaxially sparsely or densely scabrous, trichomes ca. 1.5 mm long; abaxial surface reddish-hirsute on veins, trichomes multicellular, ca. 1 mm long. Inflorescence axillary, with 2–5 flowers in dichasial cymes, peduncle tinged reddish, ca. 8 cm long, glabrous; pedicel 8–9 mm long, glabrous. Bracts ovate, margin sparingly reddish ciliate, 3.5–4 mm long, 2.5–3 mm wide. Staminate flower: tepals 4, outer 2 orbicular-ovate to ovate, margin entire, white or tinged pinkish, 9–15 mm long, 9–13 mm wide, abaxially sparsely reddish-hirtellous; inner 2 oblanceolate, white, 11–13 mm long, 3.5–4 mm wide; androecium zygomorphic, stamens 20–25, yellow, filaments 0.8–1 mm long, anthers ca. 1.5–1.7 mm long. Carpellate flower: tepals 3, glabrous, outer 2 orbicular or suborbicular, tinged pinkish, 12–14 mm long, 12–13 mm wide, margin entire; inner 1 oblanceolate, 8–10 mm long, 3–5 mm wide, white; ovary trigonous-ellipsoid, pinkish, 7–8 mm long, 4–5 mm across, glabrous, 3-winged, abaxial wing crescent-shaped, 3–5 mm tall, lateral wings 2–3 mm tall; styles 3, ca. 4 mm long, fused to 1/3 at base, bifurcating with yellow stigma forming a continuous Ushaped papillose band. Capsule trigonous-ellipsoid, 7–8 mm long, 4–5 mm across, abaxial wing crescent-shaped to elliptic, 8–9 mm tall, lateral wings crescent shaped, 3–4 mm tall. Seeds many, ellipsoid, truncate at both ends, brownish, 0.4–0.5 mm long, 0.2–0.25 mm thick.

Ecology and distribution:— Endemic to limestone karst areas in Cuc Phuong National Park, Ninh Binh Province, Vietnam ( Fig. 3 ), elev. 320– 400 m. It grows on steep rocky slope surface or rock crevices in semishaded or shady broad-leaved forest.

Etymology:— The epithet 'calciphila' refers to the new species’ definite preference to limestone substrate. Although the name ‘ Begonia semicava Irmsch. ' has appeared on some specimens in Vietnamese herbaria (CPNP, HNU) and checklists ( Frontier Vietnam 1994, 2002; Ho 1991), it was based on unpublished annotations by the late Dr. Edgar Imscher. This unpublished name has been excluded from the checklist of Southeast Asian Begonia ( Hughes 2008) .

Additional specimen examined:— VIETNAM. Ninh Binh Province, Cuc Phuong National Park , collected on limestone mountain, Oct 1964, Ngoc Bich s. n. ( HNU) ; Bong, Cuc Phuong National Park . 1 December 1969, Nguyen Huu Hien B442 ( CPNP) ; Ninh Binh Province, Nho Quan District, Cuc Phuong National Park, CP117 . Hill southwest of helipad, primary forest on limestone slope, growing on rock crevice under dark forest floor, common, elev. 320–405 m, 20°21'00"N, 105°36'00"E, 18 November, 1999. D.D. Soejarto, N. T. Hiep, N. M. Cuong, N. Q. Binh, N. X. Tam and M. V. Xinh 11012 ( CPNP) ; Ninh Binh Province, Cuc Phuong National Park, CP213 . Dan village , limestone mountain near ranger station, in primary forest, elev. 350 m, 20°18'97"N, 105°37'75"E, 14 August 2000, N. M. Cuong, D. T. Kien and M. V. Sinh 961 ( CPNP) ; Ninh Binh Province, Cuc Phuong National Park, CP2000 . Near Bong , crowded in the herbaceous storey under evergreen broad-leaved forest, creeping herb 20 m long, 20°21'05"N, 105°35'83"E, 13 November, 2000, N. T. Hiep 4231 ( CPNP) .

Leaf anatomy and vestiture:— Adaxial surface with sparse glandular trichomes ( Fig. 4D ); cross section ca. 220 μm thick, epidermis single-layered on both surfaces, hypodermis absent ( Fig. 4E ); abaxial surface with sparse glandular trichomes and multiseriate trichomes on veins, stomata complex single, helicocytic, subsidiary cells (5–)6 ( Fig. 4F ).

Chromosome cytology:— The Asian section Coelocentrum consistently shows the chromosome number of 2 n =

30 ( Peng et al. 2012, 2013, 2014a), with the exception of some probable intraspecific autotriploid individuals with 2 n = 45 in B. longgangensis C.-I Peng & Yan Liu (2013: 54–44: 2) ( Peng et al. 2013). In this study, the diploid count of 2 n = 30 was documented for Begonia calciphila ( Fig. 5B ). The 30 chromosomes gradually varied from ca. 1.0 to 2.0 μm long. The centromere positions of most chromosomes were uncertain. However, several chromosomes were clearly metacentric. Satellites were not observed.

Notes:— Begonia calciphila shares the long creeping habit with B. auritistipula Y.M. Shui & W.H. Chen (2005: 357) , a calciphyte in southwestern Guangxi, China. The new species however differs from the latter in the petioles 2–10 cm long (vs. 9–22 cm); leaves orbicular-ovate with an acuminate apex (vs. ovate with an acute apex); leaf adaxial surface scabrous (vs. rugose and setulose); stipules villous (vs. glabrous); and petioles villous (vs. retrorsely hirsute).

Figures

FIGURE 3. Distribution map of Begonia abbreviata (■), B. calciphila (Ì), B. sphenantheroides (●) and B. tamdaoensis (▲) in Vietnam.

FIGURE 4. SEM microphotographs of Begonia leaves. A–C, B. abbreviata; D–F, B. calciphila; G–I, B. sphenantheroides; J–L, B. tamdaoensis; A, D, G, J, Leaf adaxial surfaces; B, E, H, K, Leaf cross-sections; C, F, I, L, Leaf abaxial surfaces. Scale bars = 200 μm.

FIGURE 5. Somatic chromosomes at metaphase of Begonia. A. B. abbreviata (2n = 30: NTH 5917); B. B. calciphila (2n = 30: Peng et al. 20226); C. B. sphenantheroides 2n = 22: Peng et al. 20216); D. B. tamdaoensis (2n = 18: Peng et al. 16638); B’, C’, D’, somatic chromosomes serially arranged by chromosome length and centromere position. Scale bars: B’, C’= 2 μm; D’ = 5 μm. Large arrows indicate a pair of the largest metacentric chromosomes with secondary constrictions (SC) at interstitial regions of the long arms; medium arrows indicate metacentric chromosomes with SC at distal regions of the long arms. Small arrows, large arrowheads and small arrowheads indicate metacentric chromosomes, subtelocentric chromosomes and telocentric chromosomes, respectively.

FIGURE 6. Begonia calciphila C.-I Peng.A, Habit; B, Stipule, abaxial view; B’, Stipule, adaxial view; C, Bract; D, Staminate flower; E, Carpellate flower; F, Androecium, F’, stamens; G, Style and stigma; H, Cross section of ovary; I, Fruit. All from C.-I Peng et al. 20226 (HAST). Line drawing by Ming-Chao Yu.

FIGURE 7. Begonia calciphila C.-I Peng. A, Habit and habitat; B, Leaf, adaxial surface; C, Cultivated plant; D, Portion of rhizome, showing indumentum, petioles and stipules; E, Bracts; F, Cross section of ovary; G, Seed SEM; H, I, Inflorescence; J, Fruit. [All from C.-I Peng et al. 20226 (HAST)].