A Taxonomic and Evolutionary Review of the South American Hierochloë Section Monoecia (Poaceae: Anthoxanthinae)

Abstract

[Abstract] An integrative approach combining morphological, molecular and cytological information was used to assess the taxonomy and biogeography of Hierochloë section Monoecia. More specifically, we aimed to evaluate (1) if the morphological and molecular data are in concert with the current taxonomy of the group and (2) if speciation in this exclusively South American group could be linked to the formation of the Andes. Our analysis of 31 macro- and micromorphological characters, four plastid and nuclear DNA regions, and nuclear DNA content suggests that the taxonomic status of several of the species in the section is not justified based on either the phylogenetic (apomorphic) or the phenetic species concepts. We propose that only four out of the eight species in the section (H. pusilla, H. juncifolia, H. quebrada and H. redolens) should be recognized and the remaining taxa (H. altissima, H. gunckelii, H. spicata and H. utriculata) should be reduced to varieties of the widespread H. redolens. In addition, we recover a biogeographical scenario for section Monoecia including genetic exchange between the southern and the central Andes, recent and incomplete diversification in the southern Andes, and longer isolation history for those species in the section with restricted ecological and/or geographical ranges.