Search

The genus Cayratia Juss. in the traditional sense (i.e., Cayratia s.l.) of the grape family has been shown to be non‐monophyletic. Previous studies supported the splitting of Cayratia s.l. into three genera, that is, Cayratia s.s., Causonis Raf., 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 internal transcribed spacer 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 infold cavities in cross‐section. Three clades are detected within Afrocayratia, with A. debilis (Baker) J.Wen & L.M.Lu as the first diverged lineage. The second diverged lineage includes A. delicatula (Willems) J.Wen & Z.D.Chen and A. gracilis (Guill. & Perr.) J.Wen & Z.D.Chen. The third diverged lineage includes A. imerinensis (Baker) J.Wen & L.M.Lu, A. longiflora (Desc.) J.Wen & Rabarijaona, and A. triternata (Baker) J.Wen & Rabarijaona from Madagascar, which form a monophyletic group that 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. [ABSTRACT FROM AUTHOR]

Abstract: Tetrastigma (Miq.) Planch. (Vitaceae) is a genus with ca. 100 species showing great morphological diversity. Previous molecular phylogenetic studies suggested that traditional classification systems are not consistent with the molecular phylogeny, and Tetrastigma is undergoing further systematic investigation. We traced the evolutionary trends of 20 morphological characters within a robust phylogenetic framework. Our results revealed that many morphological characters show either multiple transitions or few state changes, however, some characters show distinct variation. The two subgenera in Tetrastigma (subgen. Tetrastigma and subgen. Palmicirrata) based on unbranched/bifurcate versus digitately branched tendrils are not supported because subgen. Tetrastigma is paraphyletic. However, the unbranched versus bifurcate/digitately branched tendril is of taxonomic utility to characterize some of the major clades. Inflorescences in Tetrastigma appear axillary, but are leaf‐opposed on a compressed axillary shoot. We found most of the species in Tetrastigma retained the ancestral compound dichasial inflorescence, except those of clade IV that have derived pseudo‐umbellate inflorescences. Other characters including habit, leaf organization, and berry shape provide additional morphological support for the major clades. Our morphological analysis and recent molecular study suggest each of the five major clades within Tetrastigma be treated as distinct taxonomic sections (five sections in the genus). [ABSTRACT FROM AUTHOR]