Paranephelius (Asteraceae: Liabeae): A case study in high-elevation hybridization and taxonomic insights

Abstract

Paranephelius Poepp. (Liabeae: Asteraceae) is a genus, here comprised of three species confined to high-elevation Andean habitats from 3°–25°S latitude from northern Peru to northern Argentina. In a prior investigation, sequence data was analyzed from samples throughout the range of the genus to evaluate the morphological variation used in delineating species. This detailed sampling allowed for molecular studies at a fine geographic scale. Within Paranephelius, genetic divergence is low, and not adequate to fully resolve phylogenetic relationships at the species level. Two genetically and morphologically recognizable genomes were reveled in northern Peru; these correspond to P. ovatus Wedd. and P. uniflorus Poepp., respectively. Several accessions possess sequences representing putative hybrids between these two species. These putative hybrids have caused taxonomic confusion in establishing species boundaries in Paranephelius. The molecular analysis suggested that P. asperifolius (Muschl.) H. Rob. & Brettell, distributed in Bolivia and northwestern Argentina, is related to P. ovatus, while it most closely resembles P. uniflorus. Species that have changed status include, P. ferreyrae H. Rob., here within the parameters of P. uniflorus; and P. jelskii (Hieron.) H. Rob. & Brettell, P. bullatus A. Gray ex Wedd., and P. wurdackii H. Rob. are here within parameters of P. ovatus. This study is not intended to be a monograph, but does includes a key to species, descriptions, illustrations, and citation of specimens examined.