Lachesiodendron, a new monospecific genus segregated from Piptadenia (Leguminosae: Caesalpinioideae: mimosoid clade): Evidence from morphology and molecules

Abstract

The widest historical circumscription of the mimosoid legume genus Piptadenia (Caesalpinioideae: mimosoid clade) previously embraced morphologically disparate species that are currently ascribed to nine different genera. Previous molecular phylogenetic studies have demonstrated that the neotropical dry forest Piptadenia viridiflora is not closely related to Piptadenia s.str. Here we plug gaps in the DNA sequence dataset of a recently published study to build a more comprehensive phylogeny of the Piptadenia group and revise morphological evidence to define the phylogenetic relationship of P. viridiflora. Both morphological and molecular data confirm that P. viridiflora is an isolated lineage, thus warranting the description of the new monospecific genus Lachesiodendron. The new genus is diagnosed by the combination of paired stipular spines (vs. stipules not modified into spines in Piptadenia s.str.), prickles absent (vs. present), flowers in axillary spikes not grouped in compound inflorescences (vs. spikes grouped in compound pseudoracemes or panicles), flowers with a cylindrical corolla long exserted from the calyx (vs. corolla campanulate with petals free or slightly joined at the base) and long green stamens (vs. shorter and white, pale yellow or pink stamens). In addition, Lachesiodendron has pollen aggregated into 8–celled polyads with a hamulate exine, which further contrasts with the 12–celled polyads with a psilate exine in Piptadenia s.str.

Hybrid capture of 964 nuclear genes resolves evolutionary relationships in the mimosoid legumes and reveals the polytomous origins of a large pantropical radiation

“…We quantified gene tree conflict in more detail for three questionable deeper nodes along the backbone of the phylogeny (Fig. 7B–D): (1) placement of Chidlowia , (2) placement of Prosopis laevigata , and (3) mono/paraphyly of the Piptadenia group sensu Lewis et al (2005) but excluding Parkia , Anadenanthera , and the recently segregated Lachesiodendron (Ribeiro et al, 2018). The same was done for the backbone of the ingoid clade (Fig.…”

“…The Mimosa clade includes Adenopodia, Mimosa, and Piptadenia. The monotypic genus Lachesiodendron, recently segregated from Piptadenia (Ribeiro et al, 2018), is placed outside both these clades and instead forms the sister group of the remainder of the Piptadenia group and the ingoid clade.…”

Extrafloral nectaries in Leguminosae: phylogenetic distribution, morphological diversity and evolution

“…We follow the subfamily classification of Legume Phylogeny Working Group (2017), and lists of accepted genera of Lewis et al (2005) and updates in Lewis et al (2013) and Legume Phylogeny Working Group (2017), which already encompass the revised generic systems of Vigna by Delgado-Salinas et al (2011), Paloue by Redden et al (2018), and the Caesalpinia group by Gagnon et al (2015Gagnon et al ( , 2016. New genera published after Legume Phylogeny Working Group (2017), such as Parasenegalia and Pseudosenegalia (Seigler et al 2017) and Lachesiodendron (Ribeiro et al 2018), were also included. In several cases, known issues of non-monophyly of genera were taken into account when assessing occurrence of EFNs (e.g.…”

Clado Mimosoide (Leguminosae e Caesalpinioideae) no Parque Estadual da Serra dos Montes Altos, Bahia, Brasil

“…Inga laurina é facilmente distinta das outras espécies do clado Mimosoide ocorrente na área de estudo por apresentar folhas paripinadas com um nectário entre cada par de folíolos e pelos frutos amarelos cujas sementes apresentam abundante arilo. Gênero monoespecífico com distribuição na América Central e na América do Sul, onde cresce em áreas de Florestas e arbustais tropicais sazonalmente secos -FATSS ou SDTFW na sigla em inglês (Ribeiro et al 2018). A sua únca espécie, Lachesiodendron viridiflorum (Kunth) P.G.Ribeiro, L.P. Queiroz & Luckow até recentemente pertencia ao gênero Piptadenia Benth., mas foi transferida para Lachesiodendron com base em evidências moleculares e morfológicas.…”

“…Sementes não observadas. Ocorre na Argentina, Bolívia, Brasil, Colômbia, Equador, Guatemala, México, Peru e Venezulela (Prado & Gibbs 1993;Ribeiro et al 2018). No Brasil tem ocorrências confirmadas em grande parte do Nordeste (Alagoas, Bahia, Ceará, Paraíba, Pernambuco, Piauí, Rio Grande do Norte, Sergipe), em Minas Gerais e Mato Grosso do Sul, onde cresce em vegetação de Caatinga, Cerrado e Floresta Estacional Decidual (BFG 2018).…”