Halimolobos, Mancoa, Pennellia, and Sphaerocardamum are New World Brassicaceae genera with their greatest species diversity in Mexico. The familial classification for these genera has been controversial. Our higher level studies, using DNA sequence data from ndhF and trnL intron, suggested that some species of these genera represent a monophyletic group. The goal of the present study was to test the monophyly of the group and their relationships relative to one another with additional species samples and data sources. Data were generated from three independent loci (chloroplast trnL intron - trnL/F spacer, nrDNA ITS, and pistillata intron 1) and morphology for 26 of their currently recognized 48 species. The difficulties associated with incorporating these data into total evidence analyses are discussed and our strategy is presented. Separate and total evidence analyses identify a monophyletic core group of Halimolobos, Mancoa, Pennellia, and Sphaerocardamum species that is closely related to members of the Arabidopsoid lineage. In addition, the results suggest that Pennellia and Sphaerocardamum are monophyletic but that Halimolobos and Mancoa are polyphyletic. Silique characteristic appear to be highly plastic within the lineage while characteristics of the corolla, seeds, and trichomes are relatively stable.

Key words: Cruciferae, Halimolobos, Mancoa, Pennellia, Phylogeny, Sphaerocardamum