Begonia fagopyrofolia W.H.Chen & Y.M.Shui, 2021

Chen, Wen-Hong, Wu, Jian-Yong, Radbouchoom, Sirilak & Shui, Yu-Min, 2021, Validation and morphology of Begonia fagopyrofolia in B. sect. Stolonifera (Begoniaceae) in China, Phytotaxa 479 (1), pp. 105-113 : 111

Begonia fagopyrofolia W.H.Chen & Y.M.Shui , sp. nov. ( Figs. 1E–H & 5 )

— Begonia fagopyrofolia W. H.Chen & Y.M.Shui , nom. nud., Shui & Chen, Seed Plants of the Karst Region in China, vol. 1., figs 116a–d, 2006. Type: Y. M . Shui & W . H . Chen 44326 (holotype, KUN!; isotype, IBSC!, KUN!, PE!)

Type:— CHINA. Yunnan Province: Lüchun County, Pinghe Community , 22° 50’16”N, 102°25’52”E, elev. 1300 m, on the path nearby village in the forests, 25 July 2005. Y. M . Shui & W. H . Chen 44326 (holotype, KUN!; isotype, IBSC!, KUN!, PE!)

Diagnosis:—The new species is similar to B. cehengensis T.C.Ku , but differs in its climbing stem, obovate to suborbicular petals of staminate and pistillate flowers, 1.5–2.2 mm long thin beak-like top of fruit, and linear-lanceolate horn-like wings of fruit. They also differ in micromorphological characteristics of their leaf epidermis, pollen grains and seeds, as previously described.

Description:—Herb, 6–10 cm tall, with creeping stems. Tubers globose, 2–5 mm in diam. Stems 4–7.5 mm tall, internodes (1–) 2–4 cm, usually with numerous stolons. Stolons 10–30 cm long and terminated by bulblets usually bearing a plant; stipules caducous, membranous, ovate, ca. 2 × 1.3 mm, apex acuminate; petiole 6.5–7 cm long, sparsely hirsute, leaf blade ovate, 5–6 × 3–4 cm at the base of the plant, gradually becoming smaller towards the apex of the plant (ca. 1 × 0.8 cm); apex acuminate, base ovate, membranous, margin irregularly crenulate, green adaxially, slightly glabrous, greenish abaxially, sparsely hirsute along veins, veins 8–10, venation palmate. Cymes axillary, 1–2-flowered, peduncle 3.5–4 cm long, sparsely hirsute; bracts ovate-lanceolate, membranous, 1.5–2 mm long, apex acuminate; pedicel 5–7 mm long. Staminate flowers: tepals 2, pinkish, obovate to suborbicular, 5–6 × 8–9 mm, glabrous, base slightly cordate; stamens numerous; filaments ca. 0.5 mm long, anthers obovate-oblong, yellow, ca. 1 mm long, apex obtuse. Pistillate flowers: tepals 2, pinkish ca. 5 × 7 mm, obovate to suborbicular; ovary obovoid, glabrous, 3-loculed, the lower part with ridges which extended along the horns, apex with a 1.5–2.2 mm beak; placentae semi-parietal, bi-lamellate in the middle of the ovary; styles 3, 1– 1.3 mm long; stigmas capitate. Capsule 3.5–4 × 4–5 mm, subequally three-horned, horns linear-lanceolate, 9–10 mm long, base ca. 1–1.6 mm wide.

Ecology and distribution:—The new species is endemic to Lüchun, southern Yunnan, China, and grows on the ground in bamboo forests or along roadsides.

Etymology:—The species is named after its leaf blade which resemble those of the genus Fagopyrum Mill. in Polygonaceae .

Phenology:—Flowering is Jul–Sep, and fruiting is Sep–Oct.

Additional specimens examined:— CHINA. Yunnan Province, Lüchun County: Pinghe Community, Nantong village , 22° 50’16”N, 102°25’52”E, elev. 1200–1300 m, 25 Aug 2003, on side of bamboo forests or on roadside. Zhou Lu-Men 524 ( KUN!); in the same locality, 15 Sep 2013, Y. M . Shui et al. B2013-598 ( KUN!); Pinghe Community, Zhedong village , elev. 1200 m, 16 Oct 2020, J. H . He HSL01000 ( KUN); Qimaba Community, 22° 49’21”N, 102°15’59”E, elev. 1267 m, on the margin of forest, 1 Aug 2005, J. H . He s.n. ( KUN!) .

Discovery process:—In 2003, a staff member of the Administration Bureau of Huanglianshan National Nature Reserve (Mr Lu-Men Zhou) collected a specimen of Begonia in Lüchun county, Yunnan, China. It was identified as Begonia cehengensis . In 2004 we separated this specimen from B. cehengensis after the authors (YMS and WHC) collected B. cehengensis in Guizhou province, China. As a result, in July 2005, YMS and WHC observed this species in Lüchun again in order to clarify the description of the flower and fruits. After much detailed observation and study, we ascertained that this species was new to science.

Conservation status:— The new species only grows on moist slopes nearby two villages (Nantong and Zhedong), at elevations of 1000–1300 m in Lüchun County in Yunnan, China. Currently there are only two populations extant, of about 200 mature individuals found in an area of 50 square meters. Unfortunately , a third population was damaged during road repairs in Qimaba community in 2016 and is still absent at this locality. Although 30% of individuals have been lost in the past five years, there is no ongoing decline in population size. So , the species merits a classification as Vulnerable ( VU, D2 ) according to IUCN standards ( IUCN 2012) .

Taxonomic comments:—The new species is also similar to B. flagellaris in B. sect. Stolonifera in creeping stems and ovate leaves ( Hara 1973), but differs in its staminate and pistillate flowers with two petals, fruit with three subequal horn-like wings and a long thin beak at the apex. In B. flagellaris , the staminate flower has four petals and the pistillate flower has five petals, the fruit is truncate at the top and the major fruit wing is lanceolate and much longer than the other two wings ( Smith et al. 1986; Tian et al. 2018). Additionally, the new species is also very similar to B. tricuspidata Clarke of B. sect. Alicida Clarke in its tuberous habit and horn-like fruit wings, but differs with its two staminate and pistillate petals (vs. four staminate petals and five pistillate petals), and thin beak-like apex of the fruit (vs. truncate) ( Smith et al. 1986; Phutthai 2011; Hughes et al. 2018).

Figures

FIGURE 1. Begonia cehengensis T.C.Ku and B. fagopyrofolia W.H.Chen & Y.M.Shui in Begonia sect.Stolonifera Y.M.Shui & W.H.Chen. A–D. Begonia cehengensis T.C.Ku (Y.M. Shui & W.H Chen B2004–522 in KUN); E–H. Begonia fagopyrofolia W. H. Chen & Y. M. Shui, sp. nov. (Y.M. Shui & W.H.Chen 44326 in KUN). A, E. Habit. B. Staminate flowers; C. Fruit; D, G and H. Pistillate flowers; F. Staminate and pistillate flowers. Scale bar:A=20 cm, B–D and F–H=5 mm, E=10 cm.All photographs were taken by Yu-Min Shui.

FIGURE 5. Illustration of Begonia fagopyrofolia W.H.Chen & Y.M.Shui, sp. nov. (Y.M.Shui & W.H.Chen 44326, KUN) A. Plant; B. Male flower; C. Open female flower; D. Young female flower; E. Adaxial view of the stamen; F. Lateral view of the stamen; G. Abaxial view of the stamen; H. Middle section of the ovary; I. Fruit. Drawn by Xi-Lin Wu.