title: A molecular phylogeny for the large African orchid genus Disa.
abstract: Phylogenetic relationships were inferred for the African subtribe Disinae (Orchidoideae, Orchidaceae), which include the large genus Disa and the small genus Schizodium. One nuclear (ITS) gene region and two plastid (trnLF and matK) gene regions were sequenced for 136 ingroup, representing 70% of all known Disinae species, as well as for 7 outgroup taxa. The combined data matrix contained 4094 characters and was analysed using parsimony and Bayesian inference. Our results show that the generic status of Schizodium can no longer be supported, as it is deeply embedded within the genus Disa. Furthermore, the currently recognised subgenera do not reflect the phylogenetic relationships and should be rejected. Several of the currently recognised sections are monophyletic, others contain misplaced elements, while some are polyphyletic. Morphological divergence, rather than convergence, has hampered previous attempts at a phylogenetic classification of the Disinae. On the basis of our molecular phylogenetic hypothesis, we propose a monotypic subtribe Disinae and a subdivision of the genus Disa into 18 sections.
authors.affiliation: Biochemistry Department, Stellenbosch University, Private Bag X1, 7602 Stellenbosch, South Africa. bytebier@sun.ac.za
authors.forename: Benny
authors.initials: B
authors.lastname: Bytebier
authors.forename: Dirk U
authors.initials: DU
authors.lastname: Bellstedt
authors.forename: H Peter
authors.initials: HP
authors.lastname: Linder
mesh_terms: D000349:Africa; D001483:Base Sequence; D001499:Bayes Theorem; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D021903:DNA, Ribosomal Spacer