4. Begonia rotundilimba S.H.Huang & Y.M.Shui (1994: 335, Fig. 3) (Fig. 4)

Ku (1999: 187), Shui et al. (2002: 317, 2019b: 218, Fig. 47D, E), Huang & Shui (2006: 171, Fig. 49), Gu et al. (2007: 196), Shui & Chen (2017: 246).

B. sect. Platycentrum (Klotzsch 1855: 243) de Candolle (1859: 134).

TYPE:— CHINA. [Yunnan Province:] Pingbian Xian, Timi, 1600–1800 m, April 1959, Exped. Univ. Yunnan 59-8 (YUKU [as YUNU]).

Ecology and phenology:— Evergreen forests, shrublands, shady moist environments, at 500–1800 m a.s.l. Flowering in April–October, fruiting from July.

Distribution: — China: Yunnan Province (Pingbian); northern Vietnam: Lao Cai Province (Bat Xat Nature Reserve) and Son La Province (Ta Xua Nature Reserve).

Note:— The species is reported here from Vietnam for the first time.

Specimens examined:— VIETNAM. Lao Cai Province: Bat Xat District, Bat Xat Nature Reserve, Y Ty Commune, 22°36’06.5’’N 103°39’03.2’’E, elev. 1420 m, 30 July 2019, Bui Hong Quang, Tran Duc Binh VN-RU 153 (HN; MW: MW0757744; photos LE: LE 01093238 http://en.herbariumle.ru/?t=occ&id=96050) ; Son La Province: Bac Yen District, Ta Xua Nature Reserve, forest margin, 21°18’44’’N 104°31’49’’E, elev. 1340 m, 06 October 2019, Nuraliev M. S., Kopylov-Guskov Yu. O., Lyskov D. F. 2835 (MW: MW0757091; photos LE: LE01093020 http:// en.herbariumle.ru/?t=occ&id=43975) ; Son La Province: Phu Yen District, Ta Xua Nature Reserve, forest on slope, 21°21’31’’N 104°39’47’’E, elev. 930 m, 09 October 2019, Nuraliev M. S., Kopylov-Guskov Yu. O., Lyskov D. F. 2892 (MW: MW0757092; photos LE: LE01093021 http://en.herbariumle.ru/?t=occ&id=43976) .