Begonia scorpiuroloba D.K.Tian & Q.Tian, 2021

Tian, Dai-Ke, Ge, Bin-Jie, Xiao, Yan, Tian, Qi & Li, Chun, 2021, Begonia scorpiuroloba, a new species in Begonia sect. Platycentrum (Begoniaceae) from southern Guangxi of China, Phytotaxa 479 (2), pp. 191-197 : 191-196

Begonia scorpiuroloba D.K.Tian & Q.Tian , sp. nov. (Ḅffi裂"海棠), Fig. 1A‒K , 2

Type:— CHINA. Guangxi Zhuangzu Autonomous Region: Fanchenggang City (防城港市), Nasuo Town (那ȒDZ), Chonghuangou Resort (冲ÊNJfiḵ), water’s edge along stream, 21.733°N, 108.051°E, elev. 130 m, 22 September 2014, Chun Li & Lihua Yang TDK2269 (holotype CSH!, CSH0149988 ) ( Fig. 3 ).

Diagnosis:—The new species is mostly similar to B. pedatifida H.Lév. (1909: 21) in the same section but differs mainly by its erect (vs. none to very short) stem at anthesis, narrower (vs. wider) lobes, leaf base obtuse (vs. acute to lobes nearly overlapping), subequal (vs. unequal) tepals of the female flowers, bractlets (vs. absent) on the pedicel near the ovary ( Fig. 1 ) and later flowering (September–October vs. June–August, rarely September). It is also similar to B. coptidifolia H.G. Ye et al. (2004: 259) in having lobed leaves, but distinguished from the latter easily by its larger plant size, single (vs. compound to nearly so) leaves, obtuse (vs. acute) angle of the leaf base, and bractlets present (vs. absent) on the pedicel near the ovary. On the phylogenetic tree, B. scorpiuroloba formed a single clade separating from both B. pedatifida and B. coptidifolia (data not shown).

Description:— Herb, perennial, rhizomatous, epiphytic on rocks or in cracks, clustered into a colony or rarely isolated, monoecious, ca. 40 cm high (including 2–3 erect stem internodes at anthesis). Rhizome creeping, unbranched or few branched, brownish green, glabrous, internodes 4–9 mm long, 6–15 mm thick. Stipules persistent, reddish green, glabrous, long triangular, 14.2–15.7 × 5.4–6.3 mm, entire, apex acuminate. Leaves simple, alternate, basal with a few from short stems at anthesis, oblique broad-ovate to nearly round, 6–28 × 8–28 cm, papery, adaxially green to dark green, suberect whitish hirtellous, abaxially greyish green to purplish green to rarely red purple, pubescent; blade deeply lobed nearly to the base, 6–8 lobed, lobes divided once to twice again, apex usually caudate, looking like scorpion tail; margin serrate or double serrate with short cilia; adaxial main veins slightly raised, adaxial veins raised; leaf base obtuse to angle near 180°; petiole ascending, brown or pinkish green, 27–28 cm long, ca. 7 mm thick, pubescent when young, nearly glabrous at mature, shallowly grooved in full-length. Inflorescences dichasial cymes, 3–6, basal or from 2–3 nodes of erect stems, 11–20 cm long, peduncle green to pinkish green, glabrous, 9.2–14.8 cm long, 3.2–4.6 mm thick. Bracts light green or reddish green, ovate-triangular, glabrous or nearly so, 15.2–16.5 × 6.8– 8.4 mm, apex acuminate, entire; bractlets persistent, greenish white, ovate-triangular, 5–12.1 × 3.2–6 mm wide, apex acute. Staminate flower: pedicel white, 21–34 mm long, ca. 1.4 mm thick, glabrous; flower ca. 22 × 17 mm; tepals 4, outer 2 larger, white with reddish apex, ovate, 12–13.5 × 9.7–10.7 mm, margin entire, base rounded, apex obtuse, white with reddish top, adaxially deeply concave in the centre, prominently thicker than the edge; abaxially short and sparse white pubescent, indumentum ca. 2 mm long; longitudinal lines distinct and transparent; inner 2, pure white, glabrous, obovoid, 12.2–12.5 × 9.2–9.3 mm, glabrous, margin entire, apex obtuse or rounded; androecium sub-globose, ca. 8 × 6.5 mm; stamens 111–163, filaments basally connate, free part 1 mm long; anthers yellow, cuneiform, ca. 2 mm long, ca. 1 mm wide, flatted at apex. Pistillate flower: pedicel white, 25–28 mm long, ca. 2 mm thick, glabrous, with two greenish bractlets below the ovary; tepals horizontally spread, 5, white, apex pinkish, glabrous, long obovoid or oblanceolate, sub-equal, 16–20 × 8–12 mm, longitudinal lines distinct and transparent, apex obtuse; styles 2, free, 8–10 mm long including stigma; stigma U-shaped, highly convolute, 7–11 × 7–8 mm wide, stigmatic band spiraled up to nearly 2 circles; ovary light green, tomentose, 2-loculed, placentation axile, each placenta 2-branched. Fruits capsule, green, sparsely pinkish tomentose less than 1 mm long; 3-winged, unequal, adaxial wing green, rectangular-rounded, ca. 11 × 15–17 mm; two side wings equal, falcate, 6–7 × 16–17 mm. Flowering Sept.–Oct., fruiting Oct.–Nov..

Distribution and Habitat:—Currently known only from two localities in southern Guangxi, China ( Fig. 4 ). It grows on the rock surfaces or in rock cracks, which are near water or in the middle of a small stream, elevation 74– 300 m. The habitat is very similar to that of B. coptidifolia which is also only distributed along streams.

Conservation Status:— Begonia scorpiuroloba is found only in the type locality and aother place (see specimen records) nearby with less than 500 km 2 extent of occurrence and less than 3 km 2 area of occupancy. The unique habitat of water’s edge along stream limits the expansion of its population. Furthermore, the type locality is located outside a protected area and is a tour site and therefore, its habitat is easily influenced by human activities. Based on current data, this species should be categorized as Endangered (CR: B1B2(a)(b)v) ( IUCN, 2019).

Etymology:—The specific epithet refers to the leaf lobes which is similar to a scorpion’s tail. The Chinese name is given as “Ḅffi裂"海棠”.

Additional Species Examination:— Guangxi, Fanchenggang City, Nasuo Town, Chonghuangou Resort , 21.733°N, 108.051°E, elev. 74 m, 06 April 2013, Qi Tian, Zhengwei Wang, Kai Jiang & Cheng Du TQ02880 (paratype CSH!, CSH0174491 , CSH0174492 ) ; Same locality, 04 July 2014, Daike Tian & Lizhi Tian TDK1974 (paratype CSH!, CSH0143381 , CSH0149989 , CSH0149990 , CSH0149991 ) . Dongxing County (东※º), Dalu Town (大»公社), Napai Village (那排大队), roadside, elev. 300 m, 03 June 1960, anonymous collector 007 ( CIMG!, CIMG4858 ) ; Same village, Siyan team, mountain valley, water’s edge, 03 November 1972, Yongchang Chen 82431 ( GXMI!, GXMI009346 ) .

Notes:—The earliest specimen of B. scorpiuroloba was collected by an anonymous collector from Napai Village, Dalu Town of Dongxing County on 03 June 1960. On 3 November 1972, Yongchang Chen also collected specimen from the same locality. On 06 April 2013, Qi Tian, Zhengwei Wang, Kai Jiang & Cheng Du from Shanghai Chenshan Botanical Garden conducted a field survey on wild plants in Fangchenggang City and found this species. After seeing the photos they provided, Daike Tian considered this species as a new taxon (species or subspecies) and went to collection site for further investigation on 4 July 2014. However, the plants did not bloom yet at that time and no inflorescence was visible. On 22 September 2014, Chun Li and Lihua Yang went there and observed flowers by the request of Daike Tian.

Figures

FIGURE 1. Habitat and morphology of B. scorpiuroloba D.K.Tian & Q.Tian (A–K), leaf morphology of B. pedatifida H. Lév. (L) A. Habitat showing a patch of individuals; B. Single plant; C. Rhizome; D. Leaf with basal obtuse angle and variation in both leaf color (upper: adaxial, lower: abaxial) and lobe shape; E. Young inflorescence with bracts; F. Inflorescence with opening male flower (front view) and flower close-up view (right); G. Female flower showing front view (left) and back view (right); H. Side view of female flower (arrow indicates two bractlets on the pedicel near ovary); I. Style and stigma; J. Subequal tepals of female flower; K. Close-up of ovary dissection; L. B. pedatifida showing variation of leaf morphology from two different locations (Left two: Dujiangyan population of Sichuan province; Right: Emeishan population of the same province)

FIGURE 2. Begonia scorpiuroloba D.K. Tian & Q. Tian (drawn by Yanxin Piao) A. Plant; B. Leaf showing lobe shape variation; C. Inflorescence on short stem; D. Inflorescence at early stage of development; E. Front view of male flower; F. Front view of female flower; G. Front view of stigmas; H. Side view of styles and stigmas; I. Side view of female flower showing ovary and bractlets on the pedicel near the ovary (pointed out by the red arrow); J. Dissection of ovary showing placenta.

FIGURE 3. Holotype of Begonia scorpiuroloba D.K.Tian & Q.Tian

FIGURE 4. Distribution of B. scorpiuroloba showing two close localities in Nasuo, Fangchenggang of southern Guangxi, China