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| Begonia parvibracteata X.X.Feng, R.K.Li & Z.X.Liu, in Feng, X.-F. Huang, Y.-N. Huang, Liu, Li, Zhou, Guo, Chen et Tian, 2022. |
Abstract
The previously reported begonias in a limestone forest of Guangxi mainly belong to Begonia sect. Coelocentrum Irmscher. In this article, we described and illustrated a new species in sect. Platycentrum (Klotzsch) A.DC., Begonia parvibracteata X.X.Feng, R.K.Li & Z.X.Liu, which was discovered in a karst forest of south-western Guangxi. The begonia shows high morphological similarity to B. subhowii S.H. Huang and B. psilophylla Irmscher, but differs from the latter two in its narrower oblique-ovate asymmetric leaf blade, 4 (occasionally 6) tepals of pistillate flower and smaller membranous inflorescence bracts. Molecular phylogenetic analysis, based on ITS sequence data, supports the new species as monophyletic and distinct from B. subhowii and B. psilophylla. Considering its narrow distribution and the disturbance of human activities, the conservation status of new taxon is evaluated as “Vulnerable” (VU B1, B2 ab (i, iv, v), D2) according to the IUCN Red List Categories and Criteria.
Keywords: ITS, morphology, new taxon, southern China, taxonomy
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| Begonia parvibracteata A хabit B staminate inflorescence C, D front and back views of staminate flower E lateral view of staminate flower F stamen G, H front and back views of pistillate flower with 4 tepals I front view of pistillate flower with 6 tepals J cross section of ovary K styles and stigmas L stigmas M abaxial view of capsule showing wings N lateral view of capsule showing two shorter wings. drawn by Yunxiao Liu |
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| Habitat and morphology of Begonia parvibracteata A habitat B flowering plant C creeping rhizome D shoot top with stipule E leaf blade (adaxial) F, G leaf blade (abaxial) H erect stem with inflorescence I, J young inflorescence and bract; K, L front and back views of staminate flower with 4 tepals M lateral view of staminate flower N stamens O, P front and back views of pistillate flower with 4 tepals Q front view of pistillate flower with 6 tepals R cross section of ovary S stigmas T, U immature capsule V dried mature capsule (Photos by Z.X. Liu). |
Begonia parvibracteata X.X.Feng, R.K.Li & Z.X.Liu, sp. nov.
Chinese name: 小苞秋海棠
Diagnosis:
Begonia parvibracteata morphologically resembles B. subhowii and B. psilophylla in rhizome and leaf characters. However, it has narrowly oblique-ovate asymmetric leaf blades, 4 (rarely 6) tepals in pistillate flowers and small (6–8 × 3–5 mm) bracts in inflorescences. These characters differ from the widely ovate leaf blades, 5 (rarely 6) tepals of pistillate flowers, and distinctly large bracts in inflorescences of B. subhowii. B. parvibracteata is dissimilar to B. psilophylla in its 4 (rarely 6) tepals in pistillate flowers and asymmetric, narrowly oblique-ovate leaf blade.
Begonia parvibracteata forms a monophyletic group clustered with B. cucurbitifolia in the phylogenic tree, but the latter has nearly symmetric, 3–4 lobed leaf blade, 5-tepaled pistillate flower, definitely differing from the new species.
Etymology: The specific epithet “parvibracteata” refers to the short small bracts of the new species. The Chinese name is given as “小苞秋海棠” (Begonia with small inflorescence bracts).
Xin-Xin Feng, Xiao-Feng Huang, Yu-Ni Huang, Zhi-Xian Liu, Ren-Kun Li, Jin-Ye Zhou, Wei Guo, Xiao-Yan Chen and Dai-Ke Tian. 2022. Begonia parvibracteata, A New Species in Begonia sect. Platycentrum (Begoniaceae) from Guangxi of China, based on morphological and molecular evidence. PhytoKeys. 214: 27-38. DOI: 10.3897/phytokeys.214.90004
