The monotypic genus Bontia presents an interesting biogeographic puzzle. Bontia daphnoides is an endemic of the Caribbean islands, but is taxonomically classified as a member of the southern-hemisphere Old World family Myoporaceae. Ninety-five percent of the 250 species of Myoporaceae (sensu R. J. Chinnock; in review) are arid/semiarid shrubs and small trees endemic to Australia. Only six species in the family occur north of the equator, and of these all but Bontia daphnoides are locally distributed in the western Pacific. The supposed sister lineage to the family is the semiarid Central American tribe Leucophylleae (Scrophulariaceae), which shares anatomical similarities with Myoporaceae. Is the evolutionary history of the Caribbean Bontia daphnoides truly shared with Australian Myoporaceae, or has it instead descended from the geographically neighboring Leucophylleae? As part of an ongoing phylogenetic analysis of generic relationships in Myoporaceae, our first two data sets provide some evidence of historical relationships between these anatomically similar lineages. Parsimony and likelihood topologies have been constructed for morphological cladistic characters and aligned rpl16 intron sequences, respectively. In these topologies, Leucophylleae is a lineage independent of a monophyletic Myoporaceae (sensu Chinnock), and Bontia is derived from within the largely arid Australian genus Eremophila. The results suggest that the current position of Bontia daphnoides in the eastern Atlantic is due to dispersal from an Australian ancestral lineage.

Key words: biogeography, Bontia, morphological phylogeny, Myoporaceae, rpl16 intron, transpacific dispersal