Phylogeny of Hedyotis L. (Rubiaceae Spermacoceae): Redefining a complex Asian-Pacific assemblage
2013 (English)In: Taxon, ISSN 0040-0262, Vol. 62, no 2, 357-374 p.Article in journal (Refereed) Published
The genus Hedyotis (Rubiaceae: Spermacoceae) has long served as a repository for tropical herbaceous species that do not fit readily into other genera. Circumscribed broadly the genus becomes a highly heterogeneous assembly, but relationships of Hedyotis have been difficult to resolve and it has proven very difficult to circumscribe the genus in a more narrow sense. Here we present Bayesian phylogenetic analyses of Hedyotis using plastid (rps16, petD) and nuclear (ITS, ETS) sequence data to resolve monophyletic lineages, to test former taxonomic hypotheses, and to revise the taxa within a well-supported evolutionary framework. Four hundred and sixty-seven sequences representing 129 accessions, never previously included in any phylogenetic analyses, are newly reported. Hedyotis, as previously circumscribed, is polyphyletic, but all investigated species, except for Hedyotis coronaria, are resolved in one of three well-supported monophyletic groups. The largest clade includes all investigated species of Hedyotis from the Indian subcontinent as well as three groups of species with primarily Chinese distributions. The type species of Hedyotis (H. fruticosa) is resolved with the Indian subcontinent species and following previous suggestions this group is referred to as Hedyotis s.str. Species currently recognized under the generic names Metabolos and Pleiocraterium are resolved in Hedyotis s.str. The second-largest group comprises a series of smaller, but well-supported, clades including the Leptopetalum clade, the genus Kadua, an unnamed group distributed in Asia and the Pacific, and a large Asian group referred to here as the ExallagelDimetia clade. The third group includes a few SE Asian Hedyotis, as well as all investigated species of the genus Neanotis. Hedyotis coronaria is not closely related to other species from Asia and is resolved with Spern2acoce hispida. The analyses indicate that diplophragmous capsules and fruticosa-type seeds occur outside of Hedyotis s.str., and several species suggested to have these features are resolved in the ExallagelDimetia clade. Species suggested to have indehiscent capsules, a feature used by Bremekamp to characterize the genus Exallage, are also resolved in both the ExallagelDimetia clade and in Hedyotis s.str., but a close examination indicates that the capsules are not truly indehiscent in the Hedyotis s.str. species. One species of Metabolos and one species of Pleiocraterium are given new species names, and one species of Pleiocrateriam is transferred to Hedyotis and three species of Hedyotis are transferred to Neanotis.
Place, publisher, year, edition, pages
2013. Vol. 62, no 2, 357-374 p.
Asia, Hedyotis, phylogenetic analysis, Rubiaceae, Spermacoceae
Botany Evolutionary Biology
IdentifiersURN: urn:nbn:se:su:diva-93593DOI: 10.12705/622.2ISI: 000322751000008OAI: oai:DiVA.org:su-93593DiVA: diva2:647050
Ministry of Education of China B08044 CUN 985-3-3;
Conservation International grant for the Botanical Survey of Louisiade Archipelago, Milne Bay Province, Papua New Guinea;
J. Robert Stiffler Endowment at ODU;
Swedish Research Council;
Knut and Alice Wallenberg Foundation 2013-09-102013-09-102013-09-10Bibliographically approved