Unraveling Polyphyly in Flourensia (Asteraceae, Heliantheae, Enceliinae) and the Establishment of a New Genus Austroflourensia

Abstract

The monophyly of Flourensia was examined for the first time by sequencing the nuclear ITS and plastid psbA- trnH regions in 18 species of the genus, analyzing them along with representatives of the remaining genera of subtribe Enceliinae. Results showed strong evidence for the polyphyly of Flourensia identifying two well-supported groups: Flourensia, a clade from North America including the type F. laurifolia, and another clade, here designed as the new genus Austroflourensia, containing the South American species. Austroflourensia is related to the other four genera composing the subtribe Enceliinae, whereas Flourensia s.s. is sister to all of them. Austroflourensia can be mainly distinguished by having a shrubby or subshrubby habit, capitula always radiate usually arranged in weakly cymose-corymbose capitulescences, phyllaries 23-seriate, and disc corollas shortly dentate. This paper proposes twelve new combinations to accommodate species previously described in the genus Flourensia and provides emended descriptions of Flourensia and the new genus Austroflourensia. The illustration of the type of the new genus, a distribution map, and a key to the genera of Enceliinae are also provided.