Begonia hymenophylloides Kingdon-Ward ex L.B. Smith & Wasshausen (1984: 467)

Tian, Jing, Wang, Yan, Ren, Jing, Peng, Shuai, Wang, Jun-Jie, Zhang, Cai-Fei & Hu, Guang-Wan, 2021, Rediscovery and supplemental description of Begonia hymenophylloides (Begoniaceae) as new record in China, Phytotaxa 528 (2), pp. 139-143 : 139-142

Begonia hymenophylloides Kingdon-Ward ex L.B. Smith & Wasshausen (1984: 467) .

Type:— Myanmar. Nam Tisang-Mali Divide , 27°30′ N, 97°50′ E, elevation 1500–1800 m, 24 Aug. 1926, Ward F.K. 7334 ( K, image!)

Description:—Herb, perennial, epiphytic on trees, clustered into a colony, monoecious. Tuber globose, renewing with each growth season, 10–25 × 7–12 mm, with fibrous roots, rarely irregular verrucose, without erect stem. Stipule reddish-brown, membranous, broadly triangular, 4–5 × 2 mm, both surfaces glabrous, margin entire but ciliate. Leaf simple, solitary, basifixed, petiole reddish-brown, with green stripes, 8–16 mm long, 4–5 mm in diameter, sparsely hairy, denser on upper part; leaf blade nearly symmetrical, long ovate, usually shallowly pinnate lobed, 17–29 × 8–12 cm, base cordate, apex with caudal tip, palmate veins 5–7, margin dentate serrate; papery, adaxially leaf surface bullate, green, densely hairy; abaxially purplish red and hairy along veins. Inflorescence dichasium, 1–2, 7.5–15 cm long, sparsely hairy, denser on upper part, peduncles 2.0– 9.5 cm long. Bracts yellow-green, ovate, densely hairy, 4–5 × 2.5 mm, apex obtuse, entire. Staminate flower: pedicel 10–17 mm, villous; tepals 4, white, outer 2 larger, white, broadly ovate to elliptic, 8–12 × 6–8 mm, apex obtuse, margin entire, base rounded, adaxially glabrous, abaxially midrib with 3–5 rows of villus, villus ca. 2 mm long; inner 2, white, glabrous, obovoid, ca. 7 × 3 mm, apex obtuse, margin entire, base cuneate, both surfaces glabrous, stamens numerous (ca. 20), filaments basally connate 1.0–2.0 mm long, anther oblong. Pistillate flower: pedicel 4–10 mm long, villous, tepals 4 (5), white (with reddish apex); outer 2 larger, broadly ovate to orbicular, ca. 8 × 6 mm, apex rounded, margin entire, base rounded, adaxially glabrous, abaxially 3–5 rows of villus on midrib; inner 2 (3), ovate to obovoid, ca. 7 × 5–6 mm, apex obtuse, margin entire, base cuneate, glabrous; styles 3, free, ca. 1 mm, golden yellow, U-shaped; ovary 5 × 2–4 mm, 3-winged and 3-loculed, wings nearly equal, yellow-green, densely villous, villus ca. 2 mm long, placentae axile, bilamellate. Capsule, nearly equally 3-winged, wings obtuse triangular.

Distribution:— MYANMAR: Nam Tisang-Mali Divide and Mali Hka, north frontier to Xizang, China; CHINA (new record): Xima Township, Yingjiang County, Yunnan, under the hillside forest, 24°47′17.59″ N, 97°40′41.90″ E, elevation 1411 m, 27 July 2019, HGW-1186 (HIB).

Additional specimens examined:— MYANMAR: Mali Hka . 31 July 1937, Ward F.K. 12858 ( BM) ; MYANMAR: Mali Hka , 9 Dec 1937, Ward F.K. 13555 ( BM) .

Note:— The name of Begonia hymenophylloides was given by Francis Kingdon-Ward in 1928, but he only gave a nude name without diagnosis and description. Later, Smith and Wasshausen (1984) described this plant and validly published it. According to the location and coordinates provided in the original documents and collecting record of all collected specimens, it has been only found in northern Myanmar adjacent to the border to Xizang (Tibet) Autonomous Region of China. POWO (http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:903683-1) recorded it is also distributed in SE Xizang, but there is no exact collection evidence to support. Therefore, our collection should be the first time of this species collected from China. Due to the imperfection of the type specimens, lacking stipules and female flowers, Smith and Wasshausen didn’t describe these parts and considered the inflorescence as unisexual. We added the characteristics description of these parts and corrected its gender as monoecious.

Begonia hymenophylloides is similar to B. garrettii Craib (1930) (= B. arboreta Y.M.Shui (Shui 2002: 307–308) ( Chen et al. 2018)). Both are epiphytic on trees, and have globose tuber and simple leaf. However, the former can be easily distinguished from the latter by its smaller (14–15 × 14–17 cm vs. 17–29 × 8–12 cm) leaf adaxially bullate and densely hairy, abaxially hairy (vs. both sides glabrous) along veins, ovary densely villous (vs. glabrous).