Author(s): Guillermo C. Amico (corresponding author) , Romina Vidal-Russell , Miguel A. Garcia , Daniel L. Nickrent 
Loranthaceae includes approximately 73 genera and 915 species (Nickrent et al. 2010), representing the largest mistletoe family. Time-calibrated phylogenies (chronograms) have shown that Loranthaceae arose in the Cretaceous (as root parasites) and diversified (as stem parasites) during the Oligocene (Vidal-Russell and Nickrent 2008a). Of the 73 genera currently recognized in the family, 16 occur in South America and, except for Gaiadendron G. Don, form a monophyletic group (Vidal-Russell and Nickrent 2008b). The earliest diverging members of this South American clade possess base chromosome numbers of x = 12 (Notanthera G. Don and Tristerix Mart.), x = 10 (Ligaria Tiegh.), and x = 16 (Desmaria Tiegh.), whereas all the remaining genera are x = 8. Tripodanthus, with x = 8 is sister to the other ten x = 8 genera (Vidal-Russell and Nickrent 2008b).
Tripodanthus consists of three species, T. acutifolius Tiegh., T. flagellaris Tiegh., and T. belmirensis Roldán & Kuijt, endemic to South America. Four additional species have been described, T. eugenioides Tiegh., T. destructor Tiegh., T. ligustrinus Tiegh., and T. suaveolens Tiegh.; however, these are now considered synonyms of T. acutifolius (Barlow and Wiens 1973; Kuijt 1986).
Tripodanthus acutifolius has a disjunct distribution in South America (Fig. 1
Fig. 1.: Geographical distribution of Tripodanthus based on herbarium specimens. Filled symbols represent the accessions used in this study.
). In the eastern region it is found in northeastern Argentina, Uruguay, and south-central Brazil, whereas in the west it is present in the Guiana Highlands (Venezuela), as well as in the Andean region from Ecuador to northwestern Argentina, extending east to Bolivia and Paraguay. The Chaco biome separates the eastern populations from the Andean populations. It is unknown whether Tripodanthus acutifolius occurs in Colombia. The other two species have narrower distributions. Tripodanthus flagellaris is found in the Andes of northwestern Argentina, the Sierras Centrales of Argentina, and in northeastern Argentina, Uruguay, and south-central Brazil (eastern region). This species occurs sympatrically with T. acutifolius in two regions, the Andes of northwestern Argentina and in the eastern portions of Argentina (Abbiatti 1946) (Fig. 1). Tripodanthus belmirensis is restricted to Belmira, Antioquia, Colombia, the type locality (Roldán and Kuijt 2005). In general, Tripodanthus species are found at high elevations (> 1,000 m) in the Andes, but at low elevations in the eastern portions of South America.
Morphologically, Tripodanthus is characterized by hexamerous flowers, with isomorphic stamens, and versatile anthers. Tripodanthus acutifolius and T. flagellaris have fragrant, small (1-1.5 cm), short-tubular, white to light yellow or pink flowers, while T. belmirensis has larger (3 cm) bright red flowers. Some individuals of T. acutifolius may also have flowers that reach 3 cm in length. Tripodanthus acutifolius and T. flagellaris also possess epicortical roots, as do other South American Loranthaceae genera (not known for T. belmirensis ). As with most Loranthaceae, Tripodanthus is a stem parasitic plant, but T. acutifolius may also be amphiphagous sensu Der and Nickrent (2008). For this trophic mode, some individuals parasitize aerial parts of the...