Phylogenetics of Maxillarieae: Oncidiinae (Orchidaceae)

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This study is a continuation of our work on other subtribes of the tribe Maxillarieae, especially subtribes Zygopetalinae, Oncidiinae, and Stanhopeinae.


Subtribe Oncidiinae: We increased sampling in the Oncidiinae to 634 species representing 84 generic concepts for one region (ITS) and 250 species for additional plastid regions (matK, trnL-F), and we have added the atpB-rbcL intergenic spacer region for 126 species. The results confirm the non-monophyletic nature of Oncidium and suggest Cochlioda, Collarestuartense, Mexicoa, Miltonioides, Odontoglossum, Sigmatostalix, Solenidiopsis, and Symphyglossum should be merged into Oncidium. Based on well supported cladograms, we made numerous taxonomic changes: 1) the "mule-ear"(Lophiaris) and "rat-tail" (Cohniella) oncidiums were transferred into Trichocentrum; 2) Psygmorchis and Oncidium cristagalli were transferred to Erycina; 3) Oncidium section Serpentia was transferred to Otoglossum; 4) Oncidium sect. Cucullata was transferred to Caucaea; 5) Cyrtochilum was redefined to include Dasyglossum, Neodryas, Rusbyella, and Trigonochilum and is distinct from the core group of Oncidium; 6) Anneliesia was included in Miltonia; 7) Tolumnia includes Braasiella, Gudrunia, Hispaniella, and Olgasis. On the basis of molecular data for four sequence regions we have segregated three new genera from Oncidium: Chelyorchis, Cyrtochiloides, and Zelenkoa for species previously included in Oncidium. The relationships in subtribe in Oncidiinae are based on the combined ITS/matk/trnL-F analyses.

We are currently working on manuscripts on the Brazilian "Oncidium" clade, the genus Tolumnia and groups which have been segregated from it, and the genus Telipogon and its relatives. These papers, when published, will provide the data and rationale for merging several genera in these clades.

The Telipogon and its relatives paper has now been published.

Williams, N.H., W.M. Whitten, and R. L. Dressler. 2005. Molecular systematics of Telipogon (Orchidaceae: Oncidiinae) and its allies: nuclear and plastid dna sequence data. Lankesteriana 5: 163-184.

The numerical values are bootstrap percent support values.
Details of relationships in the Cyrtochilum alliance based on ITS/matK/trnL-F. See Williams et al. 2001b for discussion of this group.

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