title: A new molecular phylogeny and a new genus, Pendulorchis, of the Aerides-Vanda alliance (Orchidaceae: Epidendroideae).
abstract: BACKGROUND
  The Aerides-Vanda alliance is a complex group in the subtribe Aeridinae (subfamily Epidendroideae, Orchidaceae). Some phylogenetic systems of this alliance have been previously proposed based on molecular and morphological analyses. However, several taxonomic problems within this alliance as well as between it and its allies remain unsolved.
  
  
  RESULTS
  We utilized ITS and five plastid DNA regions in this phylogenetic analysis. Consensus trees strongly indicate that the Aerides-Vanda alliance is monophyletic, and the 14 genera of this alliance can be grouped into the following clades with 14 subclades: 1. Aerides, comprising two subclades: Rhynchostylis and Aerides; 2. Ascocentropsis; 3. Papilionanthe; 4. Vanda, comprising five subclades: Neofinetia, Christensonia, Seidenfadenia, Ascocentrum, and Vanda-Trudelia, in which Vanda and Trudelia form a subclade; 5. Tsiorchis, comprising three subclades: Chenorchis, Tsiorchis, and two species of Ascocentrum; 6. Paraholcoglossum; and 7. Holcoglossum. Among the 14 genera, only Ascocentrum is triphyletic: two species of the Ascocentrum subclade, an independent subclade Ascocentrum subclade in the Tsiorchis clade; the Ascocentrum subclade in the Vanda clade; and one species in the Holcoglossum clade. The Vanda and Trudelia species belong to the same subclade. The molecular conclusion is consistent with their morphological characteristics.
  
  
  CONCLUSIONS
  We elucidate the relationship among the 14 genera of the Aerides-Vanda alliance. Our phylogenetic results reveal that the Aerides-Vanda alliance is monophyletic, but it can be divided into 14 genera. The data prove that Ascocentrum is triphyletic. Plants with elongate-terete leaves and small flowers should be treated as a new genus, Pendulorchis. Saccolabium himalaicum (Ascocentrum himalaicum) should be transferred to Pendulorchis. Ascocentrum pumilum, endemic to Taiwan, should be transferred to Holcoglossum. A new combination, Holcoglossum pumilum, was also established. Trudelia should not be recognized as an independent genus. Two new species, Pendulorchis gaoligongensis and Holcoglossum singchianum, were described as well.
authors.affiliation: Shenzhen Key Laboratory for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, Shenzhen, China.
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Zhang
authors.forename: Ke-Wei
authors.initials: KW
authors.lastname: Liu
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Chen
authors.forename: Xin-Ju
authors.initials: XJ
authors.lastname: Xiao
authors.forename: Jun-Wen
authors.initials: JW
authors.lastname: Zhai
authors.forename: Li-Qiang
authors.initials: LQ
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Cai
authors.forename: Yu-Yun
authors.initials: YY
authors.lastname: Hsiao
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Rao
authors.forename: Jie
authors.initials: J
authors.lastname: Huang
authors.forename: Xue-Yong
authors.initials: XY
authors.lastname: Ma
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Chung
authors.forename: Lai-Qiang
authors.initials: LQ
authors.lastname: Huang
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Tsai
authors.forename: Zhong-Jian
authors.initials: ZJ
authors.lastname: Liu
mesh_terms: D002736:Chloroplasts / Q000235:genetics; D021901:DNA, Intergenic / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D029595:Orchidaceae / Q000145:classification* / Q000166:cytology / Q000235:genetics; D010802:Phylogeny
chemical_list: D021901:DNA, Intergenic; D018744:DNA, Plant