Phylogenomics disentangles the evolutionary and biogeographic uncertainty in Apocissus (Vitaceae)

Apocissus is an intriguing small genus in the grape family. It displays a tropical intercontinental disjunction with most species occurring in Australasia, and one in the Americas. Traditionally, its species were part of Cissus, but recent phylogenies have suggested that the Apocissus lineage diverged early from Cissus. Hence, Apocissus was formally described as a new genus, but its evolutionary history remains poorly understood. We herein conduct the first phylogenomic study on Apocissus using target-enriched genomic sequencing. We performed concatenated and coalescent-based analyses using 1,013 targeted nuclear loci of Vitaceae and 245 plastid loci. We assessed the hybridization using SNaQ and obtained a nuclear time-calibrated phylogeny with treePL. The biogeographic reconstructions were then performed with BioGeoBEARS. Nuclear reconstruction recovered the monophyly of Apocissus, and supported it as sister to Cissus, while the hybridization test did not support the hybrid origin of Apocissus. Our time-calibration and biogeographic reconstructions suggest a divergence from Cissus in the late Cretaceous and a later diversification in Australasia during the Oligocene, including a dispersal event from the Australasia to the Americas. Furthermore, our plastome reconstruction shows a close relationship between Cissus penninervis and Apocisssus, supporting the transfer of C. penninervis into Apocissus to ensure the monophyly of both genera. We herein made the taxonomic transfer, Apocissus penninervis (F.Muell.) J.Wen, Jackes & A.J.Coello, comb. nov.