When the old guys knew better: The true identity of Mimosa longepedunculata and reestablishment of M. \ud tocantina (Leguminosae, Mimosoideae)

Abstract

Megadiverse genera usually have a complex taxonomy. One factor influencing this complexity is concerned to synonyms, which are often numerous in widespread and morphologically variable species. In this article we examined the case of Mimosa longepedunculata and M. tocantina, two sympatric narrowly distributed species from central Brazil, considered to be synonyms in Barneby’s monograph. We show that this was an inaccurate taxonomic decision related to a misinterpretation of the type specimens and, possibly, also to sampling biases in field works. The definition of each species is here clarified and M. tocantina is reestablished and considered a distinct species from M. longepedunculata, having M. pseudosetosa as a new synonym. A regional identification key for the species is provided together with data on distribution and habitat, flowering and fruiting, conservation status, etymology, and notes on morphology. Illustrations, pictures and a full description of M. longepedunculata are also presented.We are grateful to the curators of CEN, HBG, NY, P, R, SPF and UB herbaria for providing access to the collections and loans of specimens, particularly Matthias Schultz and Norbert Jürgens from HBG, Marc Jeanson and Odile Poncy from P, and Vera Lúcia C. Martins from R for kindly providing and allowing use of type images; Kay Killmann for help with German translation; and two anonymous reviewers and the editor V.F. Mansano for comments on an early version of this paper. LMB thanks M.T.C. Watanabe, P.C. Baleeiro, B. Loeuille and J.B.A. Bringel for help in the field; also, FAPESP (2010/11093-1), FAPESP (2013/ 13709-8) and NSF DBI (074975) for support. JRP is supported by CNPq. This work is dedicated to E.H.G. Ule, P.H.W. Taubert and R.C. Barneb