Begonia jinyunensis (Begoniaceae, section Platycentrum), a new palmately compound leaved species from Chongqing, China.

Bo Ding,Koh Nakamura,Ching-I Peng,Meng-Jung Ho,Yoshiko Kono

doi:10.1186/s40529-014-0062-6

Abstract

BackgroundContinental China is the center of Begonia species diversity in Asia and contains more than 60 species out of about 110 named species of section Platycentrum. Mt. Jinyun, located in Chongqing City at the upper reaches of the Yangtze River, harbors a subtropical broadleaved forest with high species diversity. During a botanical survey in Mt. Jinyun, an unknown Begonia species of sect. Platycentrum with palmately compound leaves was collected and studied based on detailed morphological observations and cytological and molecular phylogenetic analyses.ResultsThe unknown Begonia bears a superficial resemblance to B. hemsleyana in having palmately compound leaves, a feature unseen in other species of sect. Platycentrum in China. It is however sharply distinct from the latter in the acaulous habit with aerial stems seen only at anthesis and long rhizomes (vs. erect stems to 70 cm or taller with short rhizomes), 4–6 pinnatilobed leaflets with indistinct, decurrent petiolules (vs. 7–10 serrate leaflets with distinct petiolules), and white (vs. pink) tepals. Molecular phylogenetic analyses based on nuclear ribosomal DNA and chloroplast DNA sequences indicated that this species was allied to Platycentrum species occurring in Southwest and South-central China and Vietnam, including B. hemsleyana, and clearly separable from these species. Somatic chromosome number of 2n = 22 was reported for this unknown species. The diploid chromosome number is agreeable with those published for Begonia sect. Platycentrum.ConclusionsThe unknown Begonia is confirmed to be a new species of sect. Platycentrum and hereto described as Begonia jinyunensis C.-I Peng, B. Ding & Q. Wang.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-014-0062-6) contains supplementary material, which is available to authorized users.

Highlights

Continental China is the center of Begonia species diversity in Asia and contains more than 60 species out of about 110 named species of section Platycentrum
Molecular phylogenetic analyses Molecular phylogenetic analyses of B. jinyunensis incorporated B. hemsleyana and 21 species (Appendix 1); these 21 species fell in the same clade with B. hemsleyana in a previous phylogenetic study on Asian Begonia based on concatenated sequences of the internal transcribed spacer (ITS) region of 18S-26S nuclear ribosomal DNA and an intron of rpl16 gene of chloroplast DNA (Chung et al 2014)
Clades supported with bootstrap percentages (BP) ≥ 50% in the maximum parsimony (MP) strict consensus tree were all recognized in the Bayesian tree

Summary

Introduction

Continental China is the center of Begonia species diversity in Asia and contains more than 60 species out of about 110 named species of section Platycentrum. Mt. Jinyun, located in Chongqing City at the upper reaches of the Yangtze River, harbors a subtropical broadleaved forest with high species diversity. During a botanical survey in Mt. Jinyun, an unknown Begonia species of sect. Platycentrum with palmately compound leaves was collected and studied based on detailed morphological observations and cytological and molecular phylogenetic analyses. The area, only 20 km away from the center of the megacity, harbors a typical forest landscape of the Yangtze River basin and high species diversity, and is protected as Jinyun Mountain National Nature Reserve with the core area of 1,235 hectares (Qing et al 2004). In a botanical survey of the nature reserve in July 2013, Bo Ding, Qian Wang, and Hai-Jun Wen collected an unknown Begonia of sect.

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