CIRCUMSCRIPTION OF THE MALVALES AND RELATIONSHIPS TO OTHER ROSIDAE - EVIDENCE FROM RBCL SEQUENCE DATA

The order Malvales remains poorly circumscribed, despite its seemingly indisputable core constituents: Bombacaceae, Malvaceae, Sterculiaceae , and Tiliaceae. We conducted a two-step parsimony analysis on 125 rbc L. sequences to clarify the composition of Malvales, to determine the relationships of some controversial families, and to identify the plac ement of the Malvales within Rosidae. We sampled taxa that have been p reviously suggested to be within, or close to, Malvales (83 sequences) , plus additional rosids (26 sequences) and nonrosid eudicots (16 sequ ences) to provide a broader framework for the analysis. The resulting trees strongly support the monophyly of the core malvalean families, l isted above. In addition, these data serve to identify a broader group of taxa that are closely associated with the core families. This expa nded malvalean clade is composed of four major subclades: (1) the core families (Bombacaceae, Malvaceae, Sterculiaceae, Tiliaceae); (2) Bixa ceae, Cochlospermaceae, and Sphaerosepalaceae (Rhopalocarpaceae); (3) Thymelaeaceae sensu late (s.l.); and (4) Cistaceae, Dipterocarpaceae s .l., Sarcolaenaceae (Chlaenaceae), and Muntingia. In addition, Neurada (Neuradaceae or Rosaceae) falls in the expanded malvalean clade but n ot clearly within any of the four major subclades. This expanded malva lean clade is sister to either the expanded capparalean clade of Rodma n ct al. or the sapindalean clade of Gadek et al. Members of Elaeocarp aceae, hypothesized by most authors as a sister group to the four core malvalean families, are shown to not fall close to these taxa. Also e xcluded as members of, or sister groups to, the expanded malvalean cla de were the families Aextoxicaceae, Barbeyaceae, Cannabinaceae, Cecrop iaceae, Dichapetalaceae, Elaeagnaceae, Euphorbiaceae s.l., Huaceae, Le cythidaceae, Moraceae s.l., Pandaceae. Plagiopteraceae, Rhamnaceae, Sc ytopetalacene, Ulmaceae, and Urticaceae.