Phylogeny of Guettardeae (Rubiaceae) and Chomelia Jacq. inferred by complete plastid genomes. Phylogeny of Guettardeae and Chomelia from chloroplast

The generic circumscriptions and relationships within the tribe Guettardeae, despite being discussed for more than two centuries, are still controversial. We aimed to infer its phylogeny by applying next generation sequencing to the genetic material obtained by targeted enrichment. Here, we present a Bayesian phylogeny for the tribe inferred from the complete plastid genomes based on a data set comprising 92 accessions from Rubiaceae (54 Guettardeae taxa from 17 genera). Emphasis was placed on Chomelia and its relationship to closely related genera within Guettardeae. The reconstructed phylogeny resolves most of the relationships within the tribe. With the exception of two species, Chomelia s.str. forms a monophyletic group, sister to Tournefortiopsis, and clearly distinct from Guettarda. Two species, Chomelia ribesioides and C. obtusa, branch within a separated clade from the remaining Chomelia species.. Guettarda sensu Achille et al. 2006 is shown to be also monophyletic, whereas Stenostomum is polyphyletic.