Molecular phylogeny and character evolution of Flemingia (Leguminosae, Papilionoideae, Phaseoleae, Cajaninae) inferred from three cpDNA and nrITS sequence data

The genus Flemingia belonging to the family Leguminosae (Papilionoideae, Phaseoleae, Cajaninae) comprises ca. 30–35 species and is distributed mainly in tropical and subtropical Africa, Asia and Oceania. Previous systematic studies of the genus Flemingia were based on morphology only, or aimed at reconstructing relationships, delimiting distinct evolutionary lineages based on morphological and molecular data, focusing on its allied genera or the tribe Phaseoleae as a whole and thus included a limited sampling of the genus Flemingia. In this present study, phylogeny of Flemingia was inferred from molecular data of three cpDNA plastid markers (matK, rps16-trnQ, and psbA-trnH) and one nuclear region (nrITS) of 73 accessions representing ca. 31 species and all five previously recognized infrageneric groups (subgenus/section) of Flemingia. Results revealed the para- and polyphyly of four previously recognized subgenera/sections within the genus Flemingia, the exception for the group Lepidocoma. Our nuclear phylogeny recovered four major clades and one single species clade, F. faginea. This species was, however, grouped in clade III (Ostryodium group) in chloroplast phylogeny. Incongruence between the trees of chloroplast and nuclear markers may point to either introgression or incomplete lineage sorting. Furthermore, the evolution of three major morphological features in Flemingia was discussed. The results of this research are not in the favor of synonymization of F. glutinosa with F. lineata, and F. ferruginea, F. cumingiana, F. phillipinensis, F. latifolia, F. prostrata, F. stricta, F. wallichi, F. grahamiana, F. sootepensis with F. macrophylla.