Phylogenetic Studies in the Euasterids II : with Particular Reference to Asterales and Escalloniaceae

Abstract: The present study is concerned with the evolutionary relationships among the Euasterids II, a group of angiosperms that includes the orders Apiales, Aquifoliales, Asterales, and Dipsacales together with several small, poorly known families yet unplaced as to order.Parsimony analysis of nucleotide sequence data from the chloroplast genes atpB, ndhF and rbcL together with morphological data are used to construct a phylogeny of the order Asterals, which in the present sense includes 11 families and more than 26 000 species. It is argued that Rousseaceae should be expanded to include also Carpodetaceae (and thus contain four genera), and that Donatia should be re-merged with Stylidiaceae. The present study also strongly supports that the sister taxon to the largest plant family, Asteraceae (Compositae), is the small South American Calyceraceae. A new addition to Asterales is Platyspermation (formerly in Escalloniaceae).Using the recently developed Bayesian approach to phylogenetic reconstruction, in combination with a dataset consisting of the atpB, ndhF and rbcL nucleotide sequences, a resolved and fairly well supported phylogeny of the Euasterids II could be reconstructed. Based on this analysis, and furthermore supported by morphological characters, the South Hemispheric family Escalloniaceae is recircumscribed to include the monogeneric families Eremosynaceae, Tribelaceae and Polyosmaceae, and in this new circumscription it includes seven genera. The formerly escalloniacean member Quintinia, together with the monogeneric families Paracryphiaceae and Sphenostemonaceae, is argued to consitute a monophyletic family Paracryphiaceae sensu lato, supported by several morphological characters.