title: New insights into the phylogeny of Burasaieae (Menispermaceae) with the recognition of a new genus and emphasis on the southern Taiwanese and mainland Chinese disjunction.
abstract: Taiwan is a continental island lying at the boundary between the Eurasian and the Philippine tectonic plates and possesses high biodiversity. Southern Taiwan, viz. Hengchun Peninsula, is notably floristically different from northern Taiwan. The floristic origin and relationships of the Hengchun Peninsula have been rarely investigated in a phylogenetic context. In this study, data from six plastid and nuclear sequences were used to reconstruct phylogenetic relationships within Burasaieae (Menispermaceae), which mainly inhabits tropical rainforests. The tree-based comparisons indicate that the position of Tinospora sensu stricto conflicts significantly between the cpDNA and ITS trees. However, alternative hypothesis tests from the ITS data did not reject the result of the cpDNA data, which suggests that tree-based comparisons might sometimes generate an artificial incongruence, especially when markers with high homoplasy are used. Based on the combined cpDNA and ITS data, we present an inter-generic phylogenetic framework for Burasaieae. Sampled species of Tinospora are placed in three different clades, including Tinospora dentata from southern Taiwan and T. sagittata from mainland China in an unresolved position alongside six lineages of Burasaieae. By integrating lines of evidence from molecular phylogeny, divergence times, and morphology, we recognize the three Tinospora clades as three different genera, including Tinospora sensu stricto, a new genus (Paratinospora) for T. dentata and T. sagittata, and Hyalosepalum resurrected. Tinospora dentata, now endemic to the Hengchun Peninsula, originated from the Late Eocene (ca. 39Ma), greatly predating the formation of Taiwan. Our study suggests that the flora of the Hengchun Peninsula contains some ancient components that might have migrated from mainland China.
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: wangwei1127@ibcas.ac.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Missouri Botanical Garden, P.O. Box 299, St. Louis, MO 63166-0299, USA.
authors.forename: Rosa Del C
authors.initials: RDC
authors.lastname: Ortiz
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China.
authors.forename: Frédéric M B
authors.initials: FMB
authors.lastname: Jacques
authors.affiliation: Department of Botany, Taiwan Forestry Research Institute, 20 Nan-Hai Road, Taipei 100, China.
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Chung
authors.affiliation: Key Laboratory of Southern Subtropical Plant Diversity, Shenzhen Fairy Lake Botanical Garden, Shenzhen 518004, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Xiao-Guo
authors.initials: XG
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Zhi-Duan
authors.initials: ZD
authors.lastname: Chen
mesh_terms: D002681:China; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D049810:Genetic Speciation; D029583:Menispermaceae / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D058974:Phylogeography; D010940:Plant Proteins / Q000235:genetics; D018087:Plastids / Q000235:genetics; D017422:Sequence Analysis, DNA; D013624:Taiwan
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins
keywords: Hyalosepalum; Paratinospora; Phylogeny; Taiwan; Tinospora; Topology test