Molecular phylogeny of the Neotropical sections of Bulbophyllum (Orchidaceae) using nuclear and plastid spacers

Abstract

AbstractThe systematic utility of sequences from two non‐coding regions of plastid DNA, psbA‐trnH and trnS‐trnG, and one nuclear region, nrITS, was examined in an assessment of phylogenetic relationships among Neotropical sections of Bulbophyllum Thouars (Orchidaceae, Epidendroideae, Dendrobieae). The nrITS region was 6 to 7 times more variable than the two cpDNA regions. No major incongruencies between the nuclear and cpDNA datasets were detected. The combined analysis revealed a well‐resolved phylogeny at sectional level based on both maximum parsimony and Bayesian approaches. Six sections of Bulbophyllum are recognized for the Neotropics. Five of these were pre‐existent but needed to be recircumscribed and one is proposed as new. We did not find disagreements between maximum parsimony and Bayesian analyses, but the latter showed better resolved relationships between the sections, which are supported by morphological features. Of the two main clades of Neotropical Bulbophyllum species, one has two lineages and occurs predominantly north of the Equator. The second contains four lineages which are highly diverse in southeastern Brazil. Our results suggest a single colonization event in the Neotropics, from Africa to northern South America, followed by dispersion through the Andes to southeastern Brazil.