Begonia leipingensis D. K. Tian, L. H. Yang & C. Li, 2016

Li, Chun, Yang, Li-Hua, Tian, Dai-Ke, Chen, Yue, Wu, Rui-Juan & Fu, Nai-Feng, 2016, Begonia leipingensis (Begoniaceae), a new compound-leaved species with unique petiolule pattern from Guangxi of China, Phytotaxa 244 (1), pp. 45-56 : 49-52

Begonia leipingensis D. K. Tian, L. H. Yang & C. Li , sp. nov. ( Fig. 5–6 ).

Type:— CHINA. Guangxi Zhuang Autonomous Region: Daxin County, Leiping Town, moist rocks under forest, 22°38’34.69’’N, 107°04’27.89’’E, elevation 264 m, 23 September 2014 (fl. and fr.), TDK-2270 ( CSH0085839 , holotype CSH!) .

Plant perennial and evergreen without erect stems, 10–45 cm high. Rhizome succulent, creeping, often branched, 5–30 cm long, 5–25 mm thick, internodes short, 5–18 mm long. Stipules persistent, reddish, triangular to narrowly triangular, 10–15 mm long and 6–8 mm wide, apex obtuse. Leaves on rhizomes, palmately compound, asymmetric, up to 30 cm long, 35 cm wide. Petioles and petiolules terete, brownish with sparse white spots, hairs whitish initially and turning brownish; petiole 3–42 cm long, 1–10 mm thick. Leaflets 2–12 and more often 3–7 ( Fig.2 ), lanceolate, 2–23 cm long, 0.7–7.3 cm wide, adaxial surface deep green and subglabrous, abaxially light green and hairy along veins, base cuneate, apex tapering, margins usually entire, few undulate, irregularly serrate to sparsely lobed; petiolule 0.3–4 cm long, 2–2.5 mm thick, spirally arranged ( Fig.1 ), middle 1–2 leaflets nearly symmetric, lateral ones slightly asymmetric; net-veined, 4–12 lateral veins each side, midrib adaxially depressed and abaxially protruded. Inflorescences 2–11, often 1–2 axillay on each rhizome branch, dichasial, 6–20 cm long, flowers 5–29 per inflorescence. Primary peduncle red-brown, 4.2–16 cm long, 1.5–3.5 mm thick, sparsely pubescent. Bracts persistent, light green and upper pinkish, triangular to narrowly triangular, apex obtuse, margin hairy, 4–7.5 mm long, 2.5–4 mm wide. Male flower: pedicel white or slightly pinkish, 11.2–27.8 mm long, 0.6–1.2 mm thick, sparsely pubescent; corolla 16–31 × 17–24 mm; tepals 4, glabrous, outer 2 larger, 9–20 × 9–17 mm, white or slightly pinkish, nearly round or wide oval, apex rounded, radial stripes not obvious on adaxial surface; inner 2 smaller, 7.5–12.5 × 3.5–5.2 mm, white, oblanceolate, apex obtuse; androecium 3.5–4.5 mm long, 5–6.5 mm in diameter, stamens 36–64; filaments free, 2 mm long, 0.2 mm thick; anthers yellow, 2 mm long, 1 mm wide, oval, apex often retuse. Female flower: pedicel white to light pink, 10–20 mm long, about 1 mm thick, sparsely pubescent; corolla 12–22 × 9–19.5 mm; tepals 3, glabrous, outer 2 larger, 8–14 × 8.5–16 mm, white to pale pink, nearly round or wide oval, apex round, radial stripes not obvious on adaxial surface; inner 1 smaller, 5–11.5 × 2.5–5 mm, white, oblanceolate; styles 3, 2–3.5 mm long, fused at base; stigma U-shaped, spirally twisted about 1.5 circles on each side; ovary sparsely pilose or subglabrous; 1-loculed with parietal placentae, bifid. Carpopodium pinkish, glabrous, 11–21 mm long, 0.8–1.2 mm in thick. Capsule nodding, ovoid, 9.5–13.5 mm long, 6.5–9.5 mm wide, unequally 3-winged, abaxial wing nearly semicircular to lunate, 6.5–11 × 10.5–16 mm, lateral wings falcate, 3–7 × 11–15.5 mm. Seeds numerous. 2n = 30 ( Fig.4 ).

Etymology: —This new species is named after the name of the town, Leiping, where it was discovered in Guangxi, southwest China.

Distribution and Habitat.: —Only one population of this new species was discovered at Xinkang Village of Leiping Town, Daxin County, Guangxi, China ( Fig. 7 ). The plants grow on moist rocks under the small trees and shrubs along shady pathsides on a limestone hill at 260–270 m elevation.

Phenology: —Flowering August to October, fruiting September to December.

Conservation Status: —Only one population, including approximately 500 individuals, was observed along about 100 m long path and nearby on a Karst hill. Although the distribution site is only four kilometers away from the town of Leiping, the habit is relatively undisturbed by human activities due to a sparse and decreasing number of local residents. According to the IUCN red list categories and criteria (IUCN 2012), B. leipingensis should be assessed as Critically Endangered (CR) based on the present situation: restricted geographic range of less than 1 km 2 with only one single location (CR:B2a) and about 300 mature individuals by estimation.

Figures

FIGURE 1. Foliage of B. leipingensis and comparison of its petiolule pattern and that of B. fangii and B. hemleyana. A–L.Young and mature leaves of B. leipingensis: A. Simple leaf (transition status) from low position of rhizome in small plants; B–L. Compound leaves with 2 to 12 leaflets; M. Line drawing of unique petiolule pattern of B. leipingensis, in which the petiolules (leaf L with 12 leaflets for exmaple) are spirally arranged; N. Line drawn petiolule pattern of B. fangii and B. hemsleyana, in which the petiolules (5 leaflets for example) develop from the same position.

FIGURE 2. Number of leaflets per leaf of Begonia leipingensis (N = 181 leaves). The 3 to 7 leaflets are the most commonly seen in mature plants, and 12 is the maximum number of leaflets ever observed during the survey.

FIGURE 4. Somatic chromosomes at metaphase of Begonia leipingensis (2n = 30, TDK-2270, CSH).

FIGURE 5. Habitat and morphology of Begonia leipingensis D. K. Tian, L. H. Yang & C. Li. A. Natural habitat; B. Small-medium individual with flowers. C. Inflorescence and flowers. D–F. Male flower (the frontal, side and back view). G. Androecium. H–I. Female flower (the frontal and side view). J–K. Young capsule (the frontal and side view). L. Cross-section of capsule with three parietal placentae. M. Dried mature capsule. N. Stipule (left: abaxial view, right: adaxial view). O. Bract (left: abaxial view, right: adaxial view). P. Large young leaf with eleven leaflets. Q. The widest leaflet ever seen in population.

FIGURE 6. Begonia leipingensis D. K. Tian, L. H. Yang & C. Li.A. Habit (small-medium plant). B. Leaf with ten leaflets (adaxial view). C. Leaflet with serrate margin in partial plants. D. Stipule. E. Bract. F. Inflorescence and flowers. G–H. Male flower (the frontal and side view).I–J. Female flower (the frontal and side view). K. Androecium. L. Filament. M–N. Three styles and stigmas (the frontal and side view). O–R. Young capsule (the side, back, adaxial and frontal view). S–T. Cross-sections of capsule (the middle, upper position).

FIGURE 7. Distribution of Begonia leipingensis in Southwest Guangxi of China.