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Systematics Section / ASPT

Salywon, Andrew [3], Snow, Neil [1], Wojciechowski, Martin F. [2], Csizmadi, Jessie [1], Landrum, Leslie [2].

Phylogenetic relationships of Myrtaceae as inferred from nrDNA ITS sequence data.

Complimentary to floristic, revisionary and monographic work in Myrtaceae, we are using sequence data from the nuclear rDNA internal transcribed spacer region to test hypotheses of generic boundaries and phylogenetic relationships within the family. The subfamily Myrtoideae has traditionally been divided into three subtribes (Eugeniinae, Myrcinae, or Myrtinae) based on characters of the embryo, sensu de Candolle and Berg. Phylogenetic analyses of 50 genera, (34 berry fruited and 16 capsular fruited, including Syzygium) support the monophyly of the Myrtoideae, with the exclusion of Syzygium, and the paraphyly of the Leptospermoideae, confirming other studies. The data do not support the monophyly of the subtribes. Rather, resulting phylograms support a rapid radiation of Myrtoideae genera with most lineages containing lots of neutral variation. The recent separation of Gossia and Lenwebbia from Austromyrtus is supported, with Gossia and Austromyrtus s.s., and Lenwebbia and Lophomyrtus as sister genera respectively. Rhodomyrtus is polyphyletic with one clade more closely related to Archirhodomyrtus and an undescribed genus from New Caledonia (see Snow, this symposium), whereas the others are more closely related to Decaspermum. The monotypic Myrtastrum, from New Caledonia, is sister to a clade containing polyphyletic Rhodomyrtus and relatives, and may be one of the earliest branching lineages of Myrtoideae. Eugenia is always monophyletic with the one species of Hexachlamys sampled as a sister lineage. Australian (one sp.) and New Caledonian species of Eugenia are sister lineages, which are in turn sister to African m embers of the genus. Mosiera is monophyletic and sister to Psidium , and is not closely related to the monotypic Myrtus in which many of the species had been placed at one time or another. Estimates of divergence times and biogeographical patterns are also examined.

1 - University of Northern Colorado, Department of Biological Sciences, Greeley, Colorado, 80639, USA
2 - Arizona State University, School of Life Sciences, PO Box 874501, Tempe, Arizona, 85287-4501, USA
3 - U. S. Water Conservation Laboratory, USDA-ARS, 4331 E Broadway Rd, Phoenix, Arizona, 85040-8807, USA

ITS sequence

Presentation Type: Paper
Session: 38-5
Location: Cottonwood A (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 3:00 PM
Abstract ID:795

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