RELATIONSHIPS IN THE ACANTHACEAE AND RELATED FAMILIES AS SUGGESTED BYCLADISTIC-ANALYSIS OF RBCL NUCLEOTIDE-SEQUENCES

A parsimony analysis of DNA sequences of the chloroplast-encoded gene rbcL from twelve members of the Acanthaceae s.l., including members of the sometimes segregate Thunbergioideae and Nelsonioideae, and other families in the Bignoniales sensu THORNE (1992) is presented. The resu lts largely agree with the classification of the Acanthaceae presented by BREMEKAMP(1965) and THORNE (1992) and support Nelsonioideae as a s ister group to the rest of the Acanthaceae. Thunbergioideae are placed as a sister to Acanthaceae s.str. Acanthus and Aphelandra, both repre sentatives of Acanthoideae, form a sister group to Ruellioideae. An an alysis of branch support found that many branches throughout the Bigno niales are weakly upheld. This points to the need for further studies in the group using more sequences of rbcL as well as other data. None of the families of Bignoniales as presently circumscribed (including A canthaceae s.l.) were strongly supported, although the larger clade co ntaining the families of the Bignoniales was robust.