Description:
<jats:title>Abstract</jats:title><jats:p>The Gnaphalieae (Asteraceae) are a cosmopolitan tribe with around 185 genera and 2000 species. The New World is one of the centers of diversity of the tribe with 24 genera and over 100 species, most of which form a clade called the <jats:italic>Lucilia</jats:italic>‐group with 21 genera. However, the generic classification of the <jats:italic>Lucilia</jats:italic>‐group has been controversial with no agreement on delimitation or circumscription of genera. Especially controversial has been the taxonomic value of achenial trichomes and molecular studies have shown equivocal results so far. The major aims of this paper are to provide a nearly complete phylogeny of the <jats:italic>Lucilia</jats:italic>‐group at generic level and to discuss the evolutionary trends and taxonomic significance of achenial trichome morphology. We conducted a phylogenetic analysis of the New World Gnaphalieae with nrDNA (ETS, ITS) sequence data from a sampling of 18 genera of the <jats:italic>Lucilia</jats:italic>‐group and utilized these results to examine morphological evolution of achenial trichome types and presence of apical myxogenic cells. Seven well‐supported subclades can be recognized within the <jats:italic>Lucilia</jats:italic>‐group (L1–L7). These results support Brazilian and Andean <jats:italic>Berroa</jats:italic>, <jats:italic>Facelis</jats:italic>, <jats:italic>Lucilia</jats:italic>, and <jats:italic>Micropsis</jats:italic> forming a clade (L1), the inclusion of Chilean <jats:italic>Lucilia</jats:italic> under <jats:italic>Belloa</jats:italic> (L2), the monophyly of <jats:italic>Stuckertiella</jats:italic> + <jats:italic>Gamochaeta</jats:italic> + <jats:italic>Gamochaetopsis</jats:italic> (L3), <jats:italic>Chevreulia</jats:italic> + <jats:italic>Cuatrecasasiella</jats:italic> (L4) and <jats:italic>Antennaria</jats:italic>(L5) excluding<jats:italic>Antennaria linearifolia</jats:italic> , which is resolved in a monophyletic group together with<jats:italic>Jalcophila</jats:italic> , <jats:italic>Loricaria</jats:italic> and <jats:italic>Mniodes</jats:italic> (L6), and the recognition of <jats:italic>Gnaphaliothamnus</jats:italic> (L7) removed from Brazilian taxa of <jats:italic>Chionolaena</jats:italic> (L2). Ancestral character state reconstruction of achenial trichome morphology suggests that clades are homogeneous in terms of trichome type, but with exceptions that make it highly homoplastic. Conversely, our results suggest that the presence of myxogenic apical cells is less homoplastic and that closely related species tend to resemble each other more than expected under random variation.</jats:p>