A molecular phylogeny of the feathery mistletoe Misodendrum (Misodendraceae)

VIDAL-RUSSELL, R.; NICKRENT, D. L.

Chico, California, EE.UU.

Congreso; Botany 2006; 2006

Botanical Society of America

MISODENDRUM comprises eight species of aerial hemiparasite shrubs endemic to temperate forests of Chile and Argentina from 33º S to 55º S. All parasitize Nothofagus, however, host ranges vary among the species. Misodendrum can be distinguished from all other mistletoes by the presence of achenes with feathery staminodes that are wind dispersed. Previous classifications (Orfila 1978, Rossow 1982) included two subgenera, Misodendrum (two sections) and Angelopogon (three sections). Our project tested this classification using molecular markers: nuclear ITS rDNA and two chloroplast genes (trnL-F and matK). All species except the rare M. macrolepis were sampled. Maximum parsimony, likelihood and Bayesian analyses were performed for individual and combined partitions. Other molecular work in our lab has shown that Misodendraceae is sister to Loranthaceae, thus this taxon was used as an outgroup. Results from analyses of the separate partitions were generally congruent, differing only in the position of M. linearifolium and M. quadriflorum; however, the 3-gene tree gave higher support for M. quadriflorum as sister to all other species. Misodendrum brachystachyum and M. oblongifolium form a well supported clade that is sister to one composed of M. punctulatum, M. gayanum and M. angulatum. This clade is sister to M. linearifolium. These phylogenetic relationships generally agree with previous classifications. Subgenus Misodendrum, characterized by warty stems and two stamens, here resolves as a polytomy: M. punctulatum, M. gayanum and M. angulatum (and likely M. macrolepis). Subgenus Angelopogon, characterized by the plesiomorphies three stamens and foliacious bracts, is paraphyletic given our rooting. Misodendrum brachystachyum and M. oblongifolium (section Archiphyllum) differ morphologically only by the length of their fruiting staminodes. M. oblongifolium is restricted to northern Patagonia where it parasitizes trees at higher elevations than the widespread M. brachystachyum. Our data suggest that M. oblongifolium could be considered a variety of M. brachystachyum.