Phylogenetic relationships within Chamaecrista sect. Xerocalyx (Leguminosae, Caesalpinioideae) inferred from the cpDNA trnE-trnT intergenic spacer and nrDNA ITS sequences

Abstract

Chamaecristabelongs to subtribe Cassiinae (Caesalpinioideae), and it comprises over 330 species, divided into six sections. The section Xerocalyx has been subjected to a profound taxonomic shuffling over the years. Therefore, we conducted a phylogenetic analysis using a cpDNAtrnE-trnTintergenic spacer and nrDNA ITS/5.8S sequences from Cassiinae taxa, in an attempt to elucidate the relationships within this section from Chamaecrista. The tree topology was congruent between the two data sets studied in which the monophyly of the genus Chamaecristawas strongly supported. Our analyses reinforce that new sectional boundaries must be defined in the Chamaecristagenus, especially the inclusion of sections Caliciopsisand Xerocalyxin sect. Chamaecrista, considered here paraphyletic. The section Xerocalyxwas strongly supported as monophyletic; however, the current data did not show C. ramosa (microphyllous) and C. desvauxii(macrophyllous) and their respective varieties in distinct clades, suggesting that speciation events are still ongoing in these specimens. © 2011, Sociedade Brasileira de Genética.