Begonia longiciliata C.Y.Wu, Acta Phytotaxon. Sinica 33(3): 251, 1995 (Wu and Ku 1995)

Tian, Dai-Ke, Xiao, Yan, Li, Yan-Ci & Yan, Ke-Jian, 2020, Several new records, synonyms, and hybrid-origin of Chinese begonias, PhytoKeys 153, pp. 13-35 : 13

Begonia longiciliata C.Y.Wu, Acta Phytotaxon. Sinica 33(3): 251, 1995 (Wu and Ku 1995) Fig. 5

- Begonia sizemoreae Kiew, Gard. Bull. Singap. 54(6): 95-100, 2004. syn. nov. Type: Vietnam, Ha Tay Province: Ba Vi National Park, no date, R. Kiew 5304 (holotype: SING!; isotype: HN!).

Type.

China, Guizou: Anlong, alt. 990 m, 14 May 1960, Guizhou Exped. 5117 (holotype: KUN!; isotye: PE!).

Note.

Begonia longiciliata (Fig. 5 ) is mostly close to B. rex Putz. (Putzey, 1857), but differs mainly by its narrower tepals of both its male and female flowers and longer anthers (up to 4 mm long) with acuminate tips that occur towards the apex of the androecium (Fig. 5I ). Notably, it has large variation in leaf colour, variegation patterns and flower colour varying from white, pink to even nearly red (Fig. 5 ). Begonia rex is only found in India, while B. longiciliata has a wide distribution from Guizhou, Guangxi and southern Yunnan of China, to the north of both Laos and Vietnam (Fig. 7 ). The name longiciliata probably refers to the long fibre-like hairs found on the adaxial leaf surface in some populations of this taxon in Guizhou Province (type locality) (Fig. 6B ), but most populations have glabrous adaxial leaf surface or nearly so (Fig. 6C ) particularly in Yunnan Province. It is also similar to B. annulata K.Koch (Koch, 1837) in leaf morphology, but can be easily separated by the latter’s hairy (vs. glabrous) tepals of both male and female flowers and fruits ( Camfield and Hughes 2018).

Begonia longiciliata has been wrongly treated as B. rex in China ( Ku 1999; Gu et al. 2007) and was even treated as a new species ( B. sizemoreae ) in 2004 ( Kiew 2004), based on a type specimen collected in Ba Vi National Park in northern Vietnam. The material from China, Vietnam and Loas is mostly similar; the imaged type plants of B. sizemoreae from northern Vietnam are nearly identical to plants of B. longiciliata from China; B. longicilata and B. sizemoreae are distributed mostly along the China-Vietnam boundary regions; recently, the species was recorded as B. sizemoreae in northern Laos ( Ding et al. 2020); no stably different key characteristics are found between B. longicilata and B. sizemoreae . Therefore, B. sizemoreae is considered by us as a synonym of B. longicilata .

Specimens examined.

China: Yunnan, Jiangcheng: Kukazai Qushui, 14 Dec. 1991, Guoda Tao 49032; Tukahe, 18 Dec 1991, Guoda Tao 47818, 49127 (HITBC); Jiahe, 23 Sept 2015, Daike Tian et al. TDK2659 (CHS). Pingzhangzhai, Pingzhang village, Jiahe, 30 Oct 2012, Jiangcheng Survey Team 5308260564 (IMDY); Jiahe to Xiaoheijiang, 21 Oct 2011, Daike Tian et al. TDK252, TDK253 (CHS); Jiangcheng county to Daheishan, 21 Oct 2011, Daike Tian et al. TDK257 (CHS). Jinping: Riverside, 22 Oct 2008, Xiaohua Jin 9467 (PE); Laomeng, 22 Nov 2007, Yumin Shui et al. 80105 (KUN). Lüchun: Laomenghe, 22 May 1974, Lüchun Team 1092 (KUN); Huanglianshan, 30 Oct 1995, Sugong Wu et al. 379 (KUN), 31 Oct 1995, Sugong Wu et al. 3354 (KUN), Sugong Wu et al. 3354 (PE), 01 Nov 1995, Sugong Wu et al. 2609 (KUN); Xiaohejiang, 18 Oct 2000, Yumin Shui & Wenhong Chen 13132, 13797 (KUN); Erpu to Banpo, 22 Oct 2000, Yumin Shui & Wenhong Chen 13620, 13696 (KUN); Erpu to Dapu, 23 Oct 2000, Yumin Shui & Wenhong Chen 14138 (KUN); 24 Oct 2000, Yumin Shui & Wenhong Chen 13848 (KUN); Xinzhai, Erpu, 03 Nov 2007, Yumin Shui et al. 72970 (KUN); Shiyazi, Daheishan, 22 Nov. 2011, Jianghai He et al. HLS0353 (KUN); Lüchun county to Manhao of Gejiu county, 25 Aug 2013, Daike Tian et al. TDK1281, TDK1283 (CHS); Daheishan, 23 Sept 2015, Daike Tian et al. TDK2661 (CHS); Dashuigou, 23 Sept 2015, Daike Tian et al. TDK2663 (CHS); Cheli of Pinghe, 23 Sept 2015, Daike Tian et al. TDK2680 (CHS); Xiaoheijiang, Xinzhai of Pinghe, 24 Sept 2015, Daike Tian et al. TDK2683, 2685 (CHS). Luquan: Mayu, 30 Oct 1995, Sugong Wu et al. 379 (PE). Mengla: Xishuangbanna Tropical Botanical Garden, Menglun, 21 Sept 2015, Daike Tian et al. TDK2629 (CHS) (cultivated). Guangxi, Longlin: Jinzhongshan, 23 May 1977, Zhou Fakai 3-0701 (GXMI); Same locality, 24 Sept 1984, Chinese Medicine Team 0185 (GXMI). Tian’e: Xiangyang, 01 May 1978, Tian’e Team 4-6-0255 (GXMI). Guizhou, Anlong: Huali of Tingya, 14 May 1960, Zhisong Zhang & Yongtian Zhang 3320 (PE); Xiaojiatang, Lishu village of Dushan, 15 Oct 2017, Daike Tian et al. TDK3473 (CHS); Xiaoanhe, Pojing of Dushan, 15 Oct 2017, Daike Tian et al. TDK3474 (CHS). Xingyi: Daojiao, Gongqiao of Zerong, 14 Oct 2017, Daike Tian et al. TDK3460 (CHS). Zhenfeng: 19 Sept 1936, Shiwei Deng 90987 (IBSC). Unknown county: Feb 1921, M. Cavalerie, unknown collection no. (P06841311) (P); Oct 1917, M. Esquirol, unknown collection no. (P05495115) (P).

Laos: Phongsaly, Tan et al. L0559 (HITBC) ( Ding et al. 2020).

Vietnam: Ba Vi National Park, Ha Tay province, R. Kiew 5304 (SING, HN); Tonkin (Mountain Bavi), Dec 1887, B. Balansa 3765 (P); Tonkin, 29 Apr 1936, M. Polane 25811 (P).

Distribution and phenology.

China: Guangxi (Longlin, Tian’e), Guizhou (Anlong, Xingyi, Zhenfeng), Yunnan (Jiangcheng, Jinping, Lüchun, Luquan); Laos (Phongsaly); Vietnam (Ba Vi) (Fig. 7 ). Alt. 300-1300 m. Flowering May to November, fruiting June to December.

Conservation status.

Near Threatened (NT). Begonia longiciliata has a relatively broad distribution, particularly in the borders of China, Laos and Vietnam (Fig. 7 ); however, the size of most populations is small and the habitats are fragmented. Its distribution range is extremely narrow in both Guangxi and Guizhou provinces of China. Several populations exist with less than 20 or even 10 individuals. In these two provinces, the population size continues to decrease, with very little seedling recruitment, due to habitat deterioration and disturbance from agricultural activities. This species also needs an environment that has a high level of humidity to survive well. Additionally, because of its beautiful foliage, wild plants are at risk of overharvesting, therefore, it should be considered Vulnerable (B2ab(iv)) in China.

Remarks.

Begonia longiciliata has been treated as a synonym of B. rex for a long time in China ( Ku 1999; Gu et al. 2007). Several horticultural cultivars have been produced by crossing it with other Begonia taxa at Kunming Botanical Garden of China ( Tian et al. 2001, 2002). However, B. rex has not been collected or observed in the wild in China. It was recorded in several locations from Arunachal Pradesh ( Camfield and Hughes 2018) (called southern Tibet by China), a currently China-India disputed region. In addition, B. longiciliata was previously cultivated under the code U3888 (with long hairs on adaxial leaf surface, Fig. 6A ) by the American Begonia Society and these cultivated plants were correctly identified as B. longiciliata by Golding ( Golding 2004), but were later treated by other researchers as B. rex ( Ku 1999; Gu et al. 2007) or B. sizemoreae ( Tebbitt 2005). Begonia longiciliata is officially established, based on our extensive field surveys, literature review, specimen examination and the observation of plants in cultivation. According to their morphological similarity and adjacent distribution, B. longiciliata and B. rex are similar to each other and they may have differentiated possibly due to geographic isolation. Further investigation is needed on their relationship and whether it is more reasonable to treat B. longiciliata as a subspecies or variety of B. rex .

Figures

Figure 5. Morphological variation of Begonia longiciliata in China (Photos by Daike Tian) A-E population from Guizhou Province: A individual with dark green leaves and white variegation (near white ring or isolated white spots) B pure green-leaved individual C fruit with one long wing and two short wings D comparison of adaxial (upper) and abaxial (low) views of leaf variation in colour and variegation E male flower (deep-pink one not shown) F-J population from Yunnan province: F female flower, showing pink variant G cross-section of ovary showing two locules and bilamillate placenta H dark-green leaved individual with a light-green ring band I male flower showing very long anther in upper portion of androecium J comparison of adaxial (upper five leaves) and abaxial (lower five leaves), showing differences in leaf colour and variegation of different individuals.

Figure 6. Comparison on hairy and glabrous adaxial leaf surface of B. longiciliata A plant with hairs (cultivated as Begonia U 388, American Begonia Society Conference 2012) B Guizhou population with hairs (arrow direction) C Yunnan population with glabrous adaxial leaf surface. (Photos by Daike Tian).

Figure 7. Distribution of Begonia longiciliata (including syn. B. sizemoreae) Triangles show distribution based on specimens and field survey and red triangles indicate type locality of B. longiciliata (Guizhou, China) and B. sizemoreae (Bavi, Vietnam), respectively.