Phylogenetic Relationships of the Genera Cladocolea and Struthanthus (Loranthaceae) with Emphasis on the Mexican Species

Abstract

Abstract— Cladocolea (Loranthaceae) is a neotropical genus currently containing 24 species. Its taxonomic history has included changes in its circumscription and the transfers of some of its species to other genera in the family. Several phylogenetic studies of Loranthaceae have recognized a close relationship between Cladocolea and Struthanthus. However, both genera were poorly represented in these studies, so here we generate a phylogeny of Mexican species of Cladocolea, Struthanthus, and related genera of Psittacanthinae, using nuclear DNA sequences of the ITS region, as well as the chloroplast regions matK and trnL-F. The sample includes 112 new sequences and an additional 12 sequences obtained from GenBank. These represent 23 taxa of Cladocolea, 14 of Struthanthus, and 10 from nine other genera of Loranthaceae. In order to understand character evolution and estimate ancestral states, 13 morphological characters were mapped, both vegetative and reproductive. Bayesian inference and Maximum likelihood analyses were performed using independent matrices and a concatenated matrix of 2842 characters. Our results show that Cladocolea and Struthanthus are both polyphyletic genera. However, the Mexican species of Cladocolea and Struthanthus with convolute or sigmoid styles form a monophyletic group. Finally, the analysis of ancestral character states indicates a trend towards a reduction of inflorescences in the Cladocolea-Struthanthus complex. New combinations and synonymies are proposed.