title: Filling in the gaps of the papilionoid legume phylogeny: the enigmatic Amazonian genus Petaladenium is a new branch of the early-diverging Amburaneae clade.
abstract: Recent deep-level phylogenies of the basal papilionoid legumes (Leguminosae, Papilionoideae) have resolved many clades, yet left the phylogenetic placement of several genera unassessed. The phylogenetically enigmatic Amazonian monospecific genus Petaladenium had been believed to be close to the genera of the Genistoid Ormosieae clade. In this paper we provide the first DNA phylogenetic study of Petaladenium and show it is not part of the large Genistoid clade, but is a new branch of the Amburaneae clade, one of the first-diverging lineages of the Papilionoideae phylogeny. This result is supported by the chemical observation that the quinolizidine alkaloids, a chemical synapomorphy of the Genistoids, are absent in Petaladenium. Parsimony and Bayesian phylogenetic analysis of nuclear ITS/5.8S and plastid matK and trnL intron agree with a new interpretation of morphology that Petaladenium is sister to Dussia, a genus comprising ∼18 species of trees largely confined to rainforests in Central America and northern South America. Petaladenium, Dussia, and Myrospermum have papilionate flowers in a clade otherwise with radial floral symmetry, loss of petals or incompletely differentiated petals. Our phylogenetic analyses also revealed well-supported resolution within the three main lineages of the ADA clade (Angylocalyceae, Dipterygeae, and Amburaneae). We also discuss further molecular phylogenetic evidence for the undersampled Amazonian genera Aldina and Monopteryx, and the tropical African Amphimas, Cordyla, Leucomphalos, and Mildbraediodendron.
authors.affiliation: Departamento de Botânica, Instituto de Biologia, Universidade Federal da Bahia, Rua Barão de Geremoabo, s/n, Campus Universitário de Ondina, 40170-115 Salvador, Bahia, Brazil; Programa de Pós-Graduação em Botânica (PPGBot), Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, Novo Horizonte, 44036-900 Feira de Santana, Bahia, Brazil. Electronic address: cardosobot@gmail.com.
authors.forename: Domingos
authors.initials: D
authors.lastname: Cardoso
authors.affiliation: Programa de Pós-Graduação em Botânica (PPGBot), Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, Novo Horizonte, 44036-900 Feira de Santana, Bahia, Brazil.
authors.forename: Wallace M B
authors.initials: WM
authors.lastname: São-Mateus
authors.affiliation: Programa de Pós-Graduação em Botânica (PPGBot), Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, Novo Horizonte, 44036-900 Feira de Santana, Bahia, Brazil.
authors.forename: Daiane Trabuco
authors.initials: DT
authors.lastname: da Cruz
authors.affiliation: Instituto Nacional de Pesquisas da Amazônia (INPA), Department of Biodiversity, Av. André Araújo, 2936, Petrópolis, 69060-001 Manaus, Amazonas, Brazil.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Zartman
authors.affiliation: Instituto Nacional de Pesquisas da Amazônia (INPA), Department of Biodiversity, Av. André Araújo, 2936, Petrópolis, 69060-001 Manaus, Amazonas, Brazil.
authors.forename: Dirce L
authors.initials: DL
authors.lastname: Komura
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Kite
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Prenner
authors.affiliation: Naturalis Biodiversity Centre, Botany Section, Darwinweg 2, 2333 CR Leiden, The Netherlands.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Wieringa
authors.affiliation: Tropical Diversity Section, Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH5 3LR, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Clark
authors.affiliation: Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.
authors.forename: Gwilym
authors.initials: G
authors.lastname: Lewis
authors.affiliation: Tropical Diversity Section, Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH5 3LR, UK.
authors.forename: R Toby
authors.initials: RT
authors.lastname: Pennington
authors.affiliation: Programa de Pós-Graduação em Botânica (PPGBot), Universidade Estadual de Feira de Santana, Av. Transnordestina, s/n, Novo Horizonte, 44036-900 Feira de Santana, Bahia, Brazil.
authors.forename: Luciano Paganucci
authors.initials: LP
authors.lastname: de Queiroz
mesh_terms: D001499:Bayes Theorem; D002489:Central America; D018744:DNA, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D007887:Fabaceae / Q000737:chemistry / Q000145:classification*; D007438:Introns; D008957:Models, Genetic; D009656:North America; D010802:Phylogeny; D018515:Plant Leaves / Q000737:chemistry; D018087:Plastids / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer
keywords: Leguminosae; Molecular phylogenetics; Papilionoideae; Quinolizidine alkaloids; Sophoreae; Swartzieae