Phylogenetics of African Rinorea (Violaceae): Elucidating Infrageneric Relationships Using Plastid and Nuclear DNA Sequences

Abstract—

Rinorea is a pantropical genus of shrubs and small trees within the family Violaceae. The genus is particularly diverse in Africa where species are ecologically important as they are often abundant or even dominant in particular forest types and act as larval host plants for highly specialized Cymothoe butterflies. Despite their importance, species identification of African Rinorea is difficult and a taxonomic revision is needed. Previous phylogenetic studies have suggested that neotropical taxa are sister to a palaeotropical clade, with multiple independent dispersals to Madagascar, but these were based on plastid data only. We therefore present an updated phylogeny of Rinorea with increased sampling of African taxa, using plastid as well as nuclear DNA sequences. Phylogenetic relationships inferred from nuclear DNA data were generally congruent with those based on evidence from plastid haplotypes from earlier studies. Our increased taxonomic sampling also revealed previously undiscovered African Rinorea clades, some of which warrant further taxonomic study. Ancestral state reconstructions refute previous hypotheses about the evolution of morphological characters traditionally used for Rinorea infrageneric classification. In addition, some widespread species may comprise species complexes. It is clear that African Rinorea require comprehensive taxonomic revision; our contribution to understanding Rinorea infrageneric relationships will facilitate this task.