Systematics Section / ASPT
Jobson, Richard , Luckow, Melissa .
Molecular Phylogenetic Study of the Genus Piptadenia (Benth.) using Plastid trnL-F and trnK Sequences.
Previous phylogenetic studies of the subfamily Mimosoideae (Fabaceae) had indicated that the New World genus Piptadenia Benth. is not monophyletic, although only three taxa were sampled. We undertook a phylogenetic study of the genus with an increased sample of 25 of the 30 recognized species using molecular markers from the plastid trnK and trnL-F regions. Parsimony jackknife results demonstrate strong support for the hypothesis that Piptadenia s.l. is polyphyletic and that there are three independent lineages. The largest group of species forms a monophyletic lineage that is sister to Mimosa and corresponds closely to section Eupiptadenia of Bentham. Three species (P. obliqua, P. moniliformis, and P. leucoxylon) of section Pityrocarpa are sister to species of Pseudopiptadenia in a lineage containing Parapiptadenia, Microlobius and Stryphnodendron. Piptadenia viridiflora is closely allied with the genera Anadenanthera and Parkia and only distantly related to either section Eupiptadenia or Pityrocarpa. Eupiptadenia is characterized by the presence of prickles, a potential synapomorphy linking it to Mimosa, and exerted, racemose or paniculiform secondary inflorescences of spikes. Piptadenia viridiflora has stipular spines and 1-2 axillary spicate primary inflorescences. Pityrocarpa are unarmed trees whose flowers have recurved petals and a strongly exerted ovary. It is recommended that Piptadenia viridiflora be recognized as a new genus, and that Piptadenia be restricted to other species of section Eupiptadenia. We also recommend that the generic name Pityrocarpa Britton and Rose be provisionally resurrected to include P. moniliformis, P. obliqua, and P. leucoxylon. Additional sampling of related genera is underway to insure that they are monophyletic relative to Pityrocarpa.
1 - Cornell University, Department of Plant Biology, Tower Road, Ithaca, New York, 14853-5908, USA
Presentation Type: Paper
Location: Cottonwood C (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 11:00 AM