Begonia caryotarum Y.M.Shui et W.H.Chen, 2021

Dong, Wen-Ke, Li, Jing-Xiu, Chen, Wen-Hong, Xiao, Bo & Shui, Yu-Min, 2021, Begonia caryotarum (Begonia sect. Platycentrum), a new species from southeast Yunnan, China, Phytotaxa 529 (1), pp. 113-118 : 113-117

Begonia caryotarum Y.M.Shui et W.H.Chen , sp. nov., Figs. 1 & 2

Type:— CHINA. Yunnan Province: Wenshan Zhuang and Miao Autonomous Prefecture , Malipo County, Babu Community , in rock crevices at the foot of limestone hills in Caryota obtusa Griff. forests, elev. ca. 900 m, cultivated at Kunming Botanical Garden , 5 July in 2021, Shui Y. M., Li J.X. et al. B2021-002 (holotype KUN!) ( Fig. 3 ) .

Diagnosis: —The new species is most similar to B. hekouensis S.H.Huang (1999: 21) in having the same petiole indumentum, flower tepal number, placentation structure, and ovary shape and color, but differs mainly in its apex of leaf blade acute (vs. acuminate), tepal pinkish- to orangish-red (vs. orangish-red), larger tepals in the staminate flower ( Table 1 ), anther connectives slightly extended (vs. obvious extended) ( Shui et al. 2017), and stigma once spiraled (vs. twice spiraled and convoluted).

Description: —Herb, monoecious, perennial, 20–40 cm tall. Rhizomes creeping, well-branched, hispid, 5–10 mm thick, internodes 5–22 mm long. Leaves simple, alternate; stipules persistent on rhizomes and erect flowering stems, red, sheath-like, triangular after being pressed, 7–11 × 4–5 mm, entire, adaxially glabrous, abaxially villous, apex acuminate with 5–6 mm aristate setae; petiole light green to purplish-red, fleshy, 7–22 cm long, densely villous; blade basifixed, asymmetric, ovate, papery, 11–16 × 9–14 cm, adaxially with sparse 5–6 mm aristate setae, base cordate with lobes overlapping or not, margin sinuate-crenate and ciliate, apex acute, venation palmate-pinnate, 6–8 primary veins, slightly impressed above and prominent beneath, adaxially green to brownish-red, glabrous, sometimes with silver spots and blotches, abaxially light green to purplish-red, densely villous on veins and veinlets. Inflorescences axillary on a short erect stem with one internode, dichasially cymose, 8–24 cm long; peduncles light green to reddish-green, villous, 4–21 cm long; bracts caducous, greyish-green, 8–9 × 5–6 mm, triangular, apex acuminate, margin entire, adaxially glabrous, abaxially with red short villous hairs; bractlets persistent, membranous, greyish-green, sparsely villous, oblong, 3–5 × 5–7 mm, apex acuminate, margin ciliate. Staminate flowers: pedicels light to reddish-green, 18–23 mm long, villous; tepals 4, outer pair larger, broadly-ovate, outer surface pinkish- to orange-red, protuberant in the middle with dense red villous hairs, sparsely villous elsewhere, inner surface pinkish-red, glabrous, 13–18 × 11–16 mm, apex obtuse to rounded, margin entire, inner pair elliptic, pink to light pink, glabrous, 10–16 × 5–10 mm, apex obtuse to rounded, margin entire; androecium actinomorphic, ca. 5 mm across; stamens orange-yellow, 80–120; filaments fused on a short stalk; anthers obovate, ca. 1.2 mm long, dehiscing by longitudinal slits, connectives slightly extended. Pistillate flowers: pedicels light to reddish-green, 16–22 mm long, villous; tepals 5, broadly ovate, outer 2 ovate, outer surface pinkish- to orange-red, sparsely villous, inner surface glabrous, 10–12 × 8–10 mm, apex acuminate, margin entire, inner 3 broadly elliptic, outer surface pink glabrous or sparsely villous, inner surface pink to light pink, glabrous, 10–17 × 7–10 mm, apex obtuse to rounded, margin entire; styles 2, shortly fused at base, light orangish-yellow, stigmas bilobed and once spiraled; ovary orange, villous, 13–15 × 10–12 mm, with 3 unequal wings, dorsal wing ca. 9 mm wide, lateral wings ca. 1.5 mm wide, 2-locular, placentation axile, with 2-branched placenta per locule. Fruits capsular, pendent, brownish-red, brown when dry, villous, dorsal wing triangular-rounded, ca. 16 mm long, lateral wings very short.

Etymology: —The specific epithet refers to the habitat of the species which occurs in Caryota obtusa forests.

Phenology: —Flowering was observed from July to August. Fruiting starts from September to October.

Distribution and habitat: —The new species grows in rock crevices at the foot of limestone hills in Caryota obtusa forests at elev. 700–900 m, in Babu Babu Community, Malipo County, Wenshan Zhuang and Miao Autonomous Prefecture, Yunnan Province, China.

Additional specimens: CHINA. Yunnan Province: Wenshan Zhuang and Miao Autonomous Prefecture, Malipo County, Babu Community, in rock crevices of limestone hill foot in Caryota obtusa forest, elev. ca. 900 m, cultivated in Kunming Botanical Garden of CAS, July 24 in 2020, Shui Y.M., Li J.X. et al. B2020-009 (KUN). The same locality, 18 July in 2021, Xiao B. s.n. (KUN).

Conservation status: — Only one small-sized population with ca. 30 mature individuals of Begonia caryotarum was observed in the type locality of ca. 1 km 2 area. The habitat is being severely damaged due to the construction of an international road between China and Vietnam. Hence this species is categorized as Critically Endangered [ CR B2 ab (ii, iv), C2 a (i)] according to the IUCN categories and criteria ( IUCN 2019) .

Notes: — Begonia caryotarum and its most similar species B. hekouensis both occur in limestone hill forests in southeast Yunnan, China. In November 2003, the pedlar of the new species plants told the second author that it came from N. Vietnam near the China-Vietnam boundary, hence it is probable B. caryotarum also occurs in N. Vietnam. If confirmation of the occurence of the species in Vietnam is obtained, it may be necessary to update the IUCN status.

Figures

FIGURE 1. Vegetative characters of Begonia caryotarum. A, habitat (arrows indicating three individuals); B, whole individuals; C, a green-leaved individual (arrow indicating a mature capsule); D, a white-spotted individual; E, rhizome and stipules (arrow indicating persistent stipules); F, adaxial view of brownish-red blade; G, abaxial view of brownish-red blade; H, adaxial view of green blade; I, abaxial view of green blade.

FIGURE 2. Reproductive characters of Begonia caryotarum.A–B, inflorescences; C, male and female flowers; D–E, staminate flower and its androecium; F–H, pistillate flower and its style and stigma; I–J, immature fruits; K–M, cross sections of ovaries from top to bottom.

FIGURE 3. Holotype of Begonia caryotarum (KUN, series bar 1514641).