Phylogenetic placement of the Peruvian-endemic genus Machaerophorus (Brassicaceae) based on molecular data and implication for its systematics

Abstract

The genus Machaerophorus includes three perennial species (M. arequipa, M. laticarpus, and M. matthioloides) inhabiting the southern Peruvian Andes. However, based on the morphological data, this genus has been reduced for more than one hundred years to synonymy of several genera of various tribes, and its phylogenetic placement using molecular data has never been studied. Therefore, in this study we explored the phylogenetic placement of Machaerophorus to test its generic status and tribal assignment, using for this purpose ribosomal nuclear (ITS) and chloroplast (trnL-F, trnH-psbA, rps16 intron) data together with a comprehensive sampling of taxa. Results obtained here demonstrated that Machaerophorus represents a well-differentiated lineage within the South American Cremolobeae–Eudemeae–Schizopetaleae clade, and hence, the genus is reinstated and excluded from the placements in Sibara and Mathewsia. Based on molecular data and morphological affinities, we included it within the tribe Schizopetaleae. A key to Machaerophorus and the genera of Schizopetaleae is also presented.