Systematics Section / ASPT
McDade, Lucinda A. , Daniel, Thomas F. , Kiel, Carrie A. .
Relationships among the major lineages of Acanthaceae s.l.: The Big Picture.
WE provide a nearly comprehensive analysis of relationships among Acanthaceae s.l. with a taxon sample that includes representatives of all known or suspected lineages and a character set that includes four cp genic regions (trnS-G, trnT-L, trnL-F, rps16) plus nuclear ribosomal ITS. Nelsonioideae (Elytraria, Nelsonia, Staurogyne) are basal. Thunbergioideae (Mendoncia + Thunbergia), Avicennia and Acanthaceae s.s. (a.k.a the retinaculate clade) are sister to Nelsonioideae with weak support for a sister group relationship between the last two. As has been shown in other studies and with strong support from morphology, Acantheae are basal within Acanthaceae s.s. Our results provide strong support for Ruellieae + Justicieae, a relationship that has likewise been supported by other analyses. Between Acantheae and Ruellieae + Justicieae are: (1) Neuracanthus, an Old World genus that has been recalcitrant to phylogenetic placement. (2) Whitfieldieae: an entirely Old World group that includes Whitfieldia, Chlamydacanthus and a series of monotypic genera endemic to Madagascar (i.e., Camarotea, Forcipella, Leandriella); Lankesteria is the basal member of this clade but without strong support. (3) Barlerieae + Andrographideae. This last relationship is both novel and very strongly supported. Andrographideae appears to be delimited as in recent classifications and the clade shares a number of synapomorphies (e.g., ‘daubenpollen’). Barlerieae are here expanded to include a number of genera of heretofore uncertain relationships (i.e., Acanthostelma, Golaea, Lasiocladus, Acanthura). Work is underway to determine whether these plants share the synapomorphies that have been understood to characterize Barlerieae (e.g., quincuncial corolla aestivation). A sister group relationship between Andrographideae and Barlerieae has not, to our knowledge, been proposed before and merits further study. These results indicate that our earlier placement of Whitfieldieae as sister to Barlerieae was in error owing to insufficient taxon sampling: the earlier analysis did not include representatives of Andrographideae.
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1 - Academy of Natural Sciences, Department of Botany, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania, 19103, USA
2 - California Academy of Sciences, Department of Botany, 875 Howard Street, San Francisco, California, 94103-3009, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 8:30 AM