| Mistletoes are plants in the sandalwood order (Santalales) that parasitize stems of other plants. Aerial parasites in Santalales are represented in four families: Misodendraceae, Loranthaceae, Santalaceae and Viscaceae. A matrix of DNA sequences from 39 taxa representing all families in Santalales was assembled to reconstruct the phylogeny. Time estimates were performed using fossil data to calibrate the phylogenetic tree. Results indicate five origins of aerial parasitism, first in Misodendraceae ca. 89 Mya and subsequently in Viscaceae (∼81 Mya), "Eremolepidaceae"(∼62 Mya), tribe Amphorogyneae in Santalaceae (∼53 Mya), and Loranthaceae (∼30 Mya). Reconstructions of parasitic mode on the phylogeny suggest that the aerial parasites evolved from ancestors that were polymorphic for either root or stem parasitism. Misodendraceae is monotypic with eight species endemic to the temperate forests of Patagonia. Previous classifications included two subgenera, Misodendrum and Angelopogon. This mistletoe is unique in that it has feathery staminodes on its wind-dispersed achenes. Two chloroplast genes and 31 morphological characters were used to reconstruct Misodendraceae phylogeny. Misodendrum quadriflorum was found to be sister to all other species. Misodendrum brachystachyum and M. oblongifolium form a well supported clade sister to subg. Misodendrum. Loranthaceae, with 73 genera and ca. 900 species, comprises mostly aerial hemiparasitic plants. Three monotypic genera considered to be relicts in the family are root parasites. It is distributed mainly in tropical areas worldwide, but loranths are also found in temperate areas of the southern hemisphere. Previous classifications divided Loranthaceae into three tribes: Elytrantheae (subtribes Elytranthinae and Gaiadendrinae), Nuytsiae and Lorantheae (subtribes Loranthinae and Psittacanthinae). To elucidate loranth phylogeny, sequences from five genes were analyzed. The three root parasites are supported as successive sister taxa to the remaining genera, resulting in a monophyletic group of aerial parasites. Three major clades are resolved, each corresponding to a previously recognized subtribe. However, the phylogenetic position of some genera is unresolved. Ancestral area reconstruction suggests an origin of the family in Gondwana with a probable vicariance event that isolated taxa in Australia and South America. Further dispersal events, probably mediated by oscine birds, from Australia into New Zealand and Asia and from Asia into Africa, are necessary to explain the current distribution of taxa. |
