New circumscription of the genus Gamochaeta (Asteraceae, Gnaphalieae) inferred from Nuclear and Plastid DNA Sequences

E. URTUBEY; A. LÓPEZ; CHEMISQUY, M. A.; ANDERBERG, A. A.; C. M. BAEZA; N. BAYON; L. P. DEBLE; A. MOREIRA-MUÑOZ; G. L. NESOM; M. H. ALFORD; L. SALOMON; S. E. FREIRE

PLANT SYSTEMATICS AND EVOLUTION

SPRINGER WIEN

Lugar: Viena; Año: 2016 vol. 302 p. 1047 - 1066

0378-2697

Abstract Gamochaeta (tribe Gnaphalieae, Asteraceae) iscomposed of ca. 60 species primarily distributed in tropicaland subtropical America. Within the tribe Gnaphalieae, thegenus is characterized by capitula arranged in spikes orhead-like clusters, few hermaphroditic central florets,truncate style branches with apical sweeping trichomes,pappus bristles connate at the base into a ring falling as aunit, and achenes with globose twin trichomes. Previousmolecular phylogenetic studies have suggested the paraphylyof the genus, but have not provided a basis forredefining generic limits due to incomplete taxon sampling.To address this problem, DNA sequences from the plastid(trnL-F) and nuclear (ETS and ITS) genomes were analyzedfrom a broad taxon sample representing the full rangeof morphological variation known in the genus. Our resultsaffirm that Gamochaeta is paraphyletic as presently circumscribed.Two clades can be recognized: one clade thatincludes the majority of the species currently assigned toGamochaeta and a second clade that includesGamochaetopsis, Stuckertiella and seven species ofGamochaeta. We present here a new circumscription ofGamochaeta, including two new combinations, Gamochaetaalpina and Gamochaeta peregrina, and the resurrectionof Gamochaeta capitata. Our results also showOmalotheca supina, O. norvegica and O. sylvatica, whichwere placed by some authors in Gamochaeta or inGnaphalium, form a monophyletic group distantly relatedto both genera.