Revision of Rhynchoglossum (Gesneriaceae) in South India and Sri Lanka, reinstating R. scabrum based on a multi-sample molecular-morphological approach

We revised the genus Rhynchoglossum papuae in South India and Sri Lanka, investigating in particular the status of R. scabrum . Based on molecular phylogenetic analyses and morphological studies, R. scabrum , endemic to South India, is re-established. It was previously synonymised with R. notonianum , but the multiple samples of the species included in the phylogenetic study were monophyletic and formed the sister clade to Sri Lankan and South Indian samples of R. notonianum . The morphological comparison to the other Rhynchoglossum entities included in this study highlighted several differences that were unique to R. scabrum , supporting the phylogenetic results and its species status. Based on the wide sampling of R. scabrum in South India, the distribution of the species could be defined. We amend the description and illustrate R. scabrum , including seed and pollen features and discuss their significance. Our combined molecular-morphological approach on multiple taxon samples proved to be a powerful tool for sorting the taxonomy of complex taxa.