New circumscription of the genus <i>Gamochaeta</i> (Asteraceae, Gnaphalieae) inferred from nuclear and plastid DNA sequences
<i>Gamochaeta</i> (tribe Gnaphalieae, Asteraceae) is composed of ca. 60 species primarily distributed in tropical and subtropical America. Within the tribe Gnaphalieae, the genus is characterized by capitula arranged in spikes or head-like clusters, few hermaphroditic central florets, tr...
| Autores: | , , , , , , , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2016 |
| País: | Argentina |
| Recursos: | Universidad Nacional de La Plata |
| Repositório: | SEDICI (UNLP) |
| Idioma: | inglês |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/133379 |
| Acesso em linha: | http://sedici.unlp.edu.ar/handle/10915/133379 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Ciencias Agrarias Gamochaetopsis Omalotheca Stuckertiella ETS ITS trnL-F |
| Resumo: | <i>Gamochaeta</i> (tribe Gnaphalieae, Asteraceae) is composed of ca. 60 species primarily distributed in tropical and subtropical America. Within the tribe Gnaphalieae, the genus is characterized by capitula arranged in spikes or head-like clusters, few hermaphroditic central florets, truncate style branches with apical sweeping trichomes, pappus bristles connate at the base into a ring falling as a unit, and achenes with globose twin trichomes. Previous molecular phylogenetic studies have suggested the paraphyly of the genus, but have not provided a basis for redefining 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 analyzed from a broad taxon sample representing the full range of morphological variation known in the genus. Our results affirm that <i>Gamochaeta</i> is paraphyletic as presently circumscribed. Two clades can be recognized: one clade that includes the majority of the species currently assigned to <i>Gamochaeta</i> and a second clade that includes <i>Gamochaetopsis</i>, <i>Stuckertiella</i> and seven species of <i>Gamochaeta</i>. We present here a new circumscription of <i>Gamochaeta</i>, including two new combinations, <i>Gamochaeta alpina</i> and <i>Gamochaeta peregrina</i>, and the resurrection of <i>Gamochaeta capitata</i>. Our results also show <i>Omalotheca supina</i>, <i>O. norvegica</i> and <i>O. sylvatica</i>, which were placed by some authors in <i>Gamochaeta</i> or in <i>Gnaphalium</i>, form a monophyletic group distantly related to both genera. |
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