J Syst Evol

• Research Articles •    

Phylogeny and taxonomy of Afrocayratia, a new genus of Vitaceae from continental Africa and Madagascar

Romer Narindra Rabarijaona1,2, Viet-Cuong Dang3, Gaurav Parmar1,2, Bing Liu1,4, Jun Wen5, Zhi-Duan Chen1,4, and Li-Min Lu1*   

  1. 1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

    2University of Chinese Academy of Sciences, Beijing 100049, China

    3Institute of Marine Biochemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam

    4Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China

    5Department of Botany, National Museum of Natural History, MRC166, Smithsonian Institution, Washington, D.C. 20013-7012 USA

  • Received:2020-07-25 Accepted:2020-10-07

Abstract: The genus Cayratia in the traditional sense (i.e., Cayratia s.l.) of the grape family has been shown not to be monophyletic. Previous studies supported the splitting of Cayratia s.l. into three genera, i.e., Cayratia s.s., Causonis, and a new genus representing the African Cayratia clade. However, the morphology of the African Cayratia clade has not been studied carefully and its phylogenetic position within Vitaceae remains unclear. Our study integrates molecular, distributional and morphological data and supports the recognition of the new genus Afrocayratia from continental Africa and Madagascar. Phylogenetic analyses strongly support the monophyly of Afrocayratia and resolve it as a sister of Cayratia s.s. based on the chloroplast data, but it is placed sister to Cyphostemma based on the ITS dataset. Molecular dating suggests that Afrocayratia split with Cayratia s.s. during the Paleocene, but that the extant species of Afrocayratia did not diversify until the early Miocene. Afrocayratia differs from its allied genera in having short stigmas and seeds with subcircular ventral infolds cavities in cross section. Three clades are detected within Afrocayratia with A. debilis as the first diverged lineage. The second diverged lineage includes A. delicatula and A. gracilis. The third diverged lineage includes from Madagascar (A. imerinensis, A. longiflora, and A. triternata) form a monophyletic group, which diverged from the second lineage in the middle Miocene. Combining the morphological and molecular evidence, we formally describe the new genus Afrocayratia, make seven new combinations, and provide a key to species of the genus.

Key words: Afrocayratia, Cayratia, Madagascar, continental Africa, molecular phylogeny, new genus, seed, Vitaceae