Testing generic limits in Cercidoideae (Leguminosae): Insights from plastid and duplicated nuclear gene sequences

Abstract

AbstractReconstructing the phylogenetic history of species in large taxonomic groups remains a challenge despite ever increasing access to molecular data. In subfamily Cercidoideae (Leguminosae), the large pantropical Bauhinia s.l. (~380 spp.) is never supported as monophyletic, but the generic boundaries and the number of genera that should be recognised remains a challenging taxonomic and phylogenetic question. Here we reconstruct the phylogeny of Bauhinia s.l. and related genera in the subfamily using sequences obtained from five loci (matK, trnL‐F, Leafy, and two previously undetected duplicate copies of Legcyc), which we analyse individually and in a concatenated matrix (excluding Leafy). The individual and concatenated analyses generally support two distinct lineages in Bauhinia s.l.: (1) the Bauhinia clade, containing Bauhinia s.str., Brenierea, and Piliostigma; and (2) the Phanera clade, containing Barklya, Cheniella, Gigasiphon, Lasiobema, Lysiphyllum, Phanera s.str., Schnella, and Tylosema. Based on our analyses, we recognise 14 genera in Cercidoideae. We resurrect the genus Tournaya from Gigasiphon, and synonymise the Asian segregate genus Lasiobema back into Phanera s.str. Our analyses reveal a clear gene duplication event in CYCLOIDEA that is shared by all Cercidoideae excluding the sister lineage to the subfamily, Cercis, supporting recent hypotheses for a whole genome duplication in all Cercidoideae except this genus.