Phylogenomic insights into historical biogeography and species delimitation of African Ampelocissus (Vitaceae).

Abstract

Ampelocissus Planch. (Vitaceae) comprises c. 95 currently recognized species that are distributed across tropical and subtropical regions in Asia, Australia, continental Africa, Madagascar, and Central America. Ampelocissus has attracted extensive attention for its close relationship with the economically important grape genus Vitis L. Despite their widespread use as food and medicinal plants, only two species have IUCN conservation status. The circumscription of several African species remains unclear due to a lack of integrative molecular and morphological studies. In this study, we conduct a comprehensive investigation of the phylogeny, biogeography, and morphological evolution of Ampelocissus using phylogenomic data with expanded taxon sampling, particularly from Africa. Our phylogenetic analyses resolve four major clades, supporting traditionally defined sections within Ampelocissus. African species of Ampelocissus are shown to be non-monophyletic, forming two lineages with distinct inflorescence types: the paniculate lineage and the cymose lineage. However, each lineage includes species from both Africa and Asia. Our biogeographic reconstruction suggests that African Ampelocissus lineages may have originated in Asia during the Eocene and supports at least two independent dispersal events from Asia to continental Africa and one from Asia to Madagascar. We further demonstrate that inflorescence type, flower-stalk, and tendril-associated inflorescences are well conserved across the phylogeny and serve as key taxonomic characteristics. Finally, we revisit the taxonomy of some controversial African Ampelocissus species and describe three new taxa from Madagascar, integrating molecular, morphological, and geographic evidence.