Relationships Among Resin-Producing Detarieae s.l. (Leguminosae) as Inferred by Molecular Data

Abstract

The tribe Detarieae s.l. (Caesalpinioideae: Leguminosae) contains a large number of genera that produce resins, but which previously had been placed in differrent generic groups. To test the monophyly of the resin-producing Detarieae and to examine phylogenetic relationships among these genera, we analyzed sequences from the chloroplast trnL intron and trnL-F spacer for more than 80 taxa and from the nuclear ribosomal Internal Transcribed Spacers (ITS) for over 50 taxa. The two chloroplast regions were highly congruent, but incongruent with the nuclear ITS data. Incongruence may be the result of hybridization, particularly in the Colophospermum and Hardwickia polyploid lineage. Resin-producing taxa are scattered among two clades, the Prioria and Detarieae s.s. clades, which together are monophyletic, but only with weak support. This group is characterized by the ability to produce bicyclic diterpenes. The phylogenetic relationships as inferred from molecular data resolved the intergeneric affinities but the main clades obtained are different from the groupings proposed by classifications based primarily on morphological characters. Based on these analyses, we propose new generic groupings that correspond to the Prioria s.s., Hardwickia, Hymenaea, Eperua s.s. and Detarium clades.