Is the genus Cissus (Vitaceae) monophyletic? Evidence from plastid and nuclear ribosomal DNA

The trnL (UAA) intron and ITS1 region were sequenced to investigate relationships among the five genera of Vitaceae present in Australia relative to Vitis. Congruent results were obtained between separate and combined data sets, with all major clades being shared among trees. All bootstrap consensus trees obtained from single sequences or combined analysis strongly suggest that Cissus is polyphyletic, corroborating the morphological inconsistencies reported previously. Cissus opaca and Clematicissus angustissima consistently grouped in a common clade. A further four taxa (C. antarctica, C. hypoglauca, C. oblonga, and C. sterculiifolia) also grouped within a clade disjunct from the main Cissus clade. Our results suggest that these five species currently classified as Cissus should be segregated from the genus. Of further interest is the close relationship between Cayratia and Tetrastigma. Overall, the results presented provide new insights into the relationships within a number of Vitaceae genera and suggest directions for future studies.\u