Abstract
New molecular evidence derived from the trnD-T region has unveiled an unexpected relationship for Mimosa pabstiana. Traditionally classified within M. sect. Batocaulon ser. Campicolae, our phylogenetic study reveals its new placement within M. sect. Batocaulon ser. Andinae. This discovery aligns with a biogeographic pattern consistent with the Pleistocene Arc Theory, encompassing inter-Andean valleys, the Chaco, Central-West Brazil, and Brazilian seasonally dry forests. Recent observations of M. pabstiana in Brazilian herbaria, along with newly collected field samples documented through photography and georeferencing, bring forth additional data about this poorly-known species. We further elucidate the phylogenetic placement of M. paraibana, previously hypothesized to have a close relationship with M. pabstiana.