Thursday, January 10, 2019

[Botany • 2018] Begonia garrettii & B. pseudodryadis • Reassessment of Begonia arboreta and B. sonlaensis (Begoniaceae) based on Field Observation and Type Examination

Begonia garrettii Craib

in Chen, Radbouchoom, Nguyen, Phutthai, Averyanov & Shui, 2018. 
 photographs by Yu-Min Shui. [Begonia arboreta Y.M.Shui]

Due to the unavailability of specimens and publications in the past, some gaps exist in knowledge of similar species from various adjacent countries. After more recently detailed observations from field surveys and examinations on herbaria specimens, we confirmed the status of Begonia arboreta and B. sonlaensis as synonyms of B. garrettii and B. pseudodryadis from China and Thailand, and from China and Vietnam, respectively. The taxonomic treatment is based on the examination of both available herbarium specimens and living plants from different populations. Taxonomy revision of the allied species is very important for understanding plant diversity in the above neighboring countries.

Keywords: Begonia, Indochina, Karstic limestone, Plant diversity, Plant taxonomy, Eudicots

Living plants of Begonia garrettii Craib [Begonia arboreta Y.M.Shui]
C. & D. Habitats; E. Plant, abaxial leaf and inflorescence; F. Male flower and close up of anther; G. Inflorescence; H. Fruit, side and front views (C–H photographs by Yu-Min Shui)

•• Begonia garrettii Craib, Bull. Misc. Inform. Kew: 411, 1930. 
Type:—THAILAND. Chiang Mai: east slope ending in Doi Pa Mawn, elev. 1450 m, 22 September 1927, flower white with violet red tinge, on rocks, aneroid, H.B.G. Garrett 462 (holotype: ABD [ABDUH 2/620]!; isotype: ABD [ABDUH: 2/619]!, K [000761183, 000761184, 000761185]!, E [00265176]!, TCD [0017184]! (Figs. 2 & 3). 

Begonia arboreta Y.M.Shui, Acta Bot. Yunnan. 24(3): 307, fig. 1, 2002. 
Type:—CHINA. Yunnan, S.K. Wu, Y.M. Shui, Y.P. Yang, L.H. Liu, J.H. He, J. Murata, H. Nagamasu, T. Sugawara, X. Chen, N. Murakami 144 (holotype: KUN [0773200]!). syn. nov. 

Distribution and Ecology:— South Yunnan in Southwestern China and Chiang Mai province in the north of Thailand (Fig. 1). It grows exclusively as an epiphyte in montane forests at elevation 1400–1860 m a.s.l. 

 •• Begonia pseudodryadis C.Y.Wu, Acta Phytotaxonom. Sin. 33(3): 251, fig. 22, 1995. 
Type:—CHINA. Yunnan: Pingbian county, Yaoshan, elev. 1320 m, on mossy rocks in valley, 6 July 1953, P.Y. Mao 2389 (holotype: KUN [0371714]!; isotype: KUN [0371713]!, IBSC [19530706]!) (Figs. 4 & 5).

 —Begonia sonlaensis Aver., Turczaninowia 15(2): 26, 2012. Type:—VIETNAM. Son La Province: L. Averyanov, CPC 1876aa (holotype: LE!). syn. nov. 

Distribution and Ecology:— The species is distributed in Southeastern Yunnan, Southwestern China, and Sonla and Dien Bien provinces, northwestern Vietnam (Fig. 1). It grows exclusively as a lithophyte on limestone karstic hills, commonly on cliffs or among rocks at elevation 670–1800 m a.s.l. 

Wen-Hong Chen, Sirilak Radbouchoom, Hieu Quang Nguyen, Thamarat Phutthai, Leonid V. Averyanov and Yu-Min Shui. 2018. Reassessment of Begonia arboreta and B. sonlaensis (Begoniaceae) based on Field Observation and Type Examination. Phytotaxa. 381(1); 132–140. DOI:  10.11646/phytotaxa.381.1.17