Systematics Section / ASPT
Krosnick, Shawn E. , Freudenstein, John .
Monophyly and Floral Character Homology of Old World Passiflora (Subgenus Decaloba: Supersection Disemma).
The circumscription of the Old World Passiflora subgenus Decaloba supersection Disemma has been unresolved for more than one hundred years. Supersection Disemma consists of 22 Old World species found throughout mainland Asia, Southeast Asia, Australia and the Pacific. They demonstrate great morphological diversity, possessing cup-shaped to tubiform flowers and both branched and unbranched inflorescences. These morphological features have been used to link species in Disemma to both New World members of subgenus Decaloba and to other genera in Passifloraceae, resulting in the widespread suspicion that Disemma is not monophyletic. Plastid and nuclear DNA sequences (trnL-F intron and spacer, ITS) were used to test the monophyly of supersection Disemma and reconstruct phylogenetic relationships within this group. Two monotypic genera, Hollrungia and Tetrapathaea, were included in this analysis based on their strong morphological similarity to Passiflora, and the Austral-Pacific distribution they share with many of the Old World species. Supersection Disemma is monophyletic, containing two distinct Asian and Australian lineages. Supersection Multiflora is sister to supersection Disemma. Hollrungia and Tetrapathaea are strongly supported as members of Passiflora, though their exact relationships to each other are not resolved. The tubiform floral morphology in the Australian species is not homologous with that in the New World species. However, the tubiform morphology of P. hollrungii from Papua New Guinea is homologous to the New World tubiform condition. The architecture of the inflorescence in Disemma is homologous with that observed in supersection Multiflora. Both supersections share a reduction of the first order stalk accompanied by higher order cymose branching. Supersections Multiflora and Disemma appear to have partially reverted to the ancestral condition of branched inflorescences in the Passifloraceae, while retaining the more derived condition of a loss of the primary stalk.
1 - Ohio State University, EEOB/ Herbarium, 1315 Kinnear Rd., Columbus, Ohio, 43212, USA
Presentation Type: Paper
Location: Cottonwood B (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 9:15 AM