A taxonomic reappraisal of the South American genus Holocalyx (Leguminosae, Papilionoideae)

The tree genus Holocalyx (Leguminosae, Papilionoideae) is distributed in southern South America and inhabits moist forests or gallery forests of the Cerrado. It is poorly studied taxonomically in spite of its economic importance as material for tool handles, rustic furniture, and fuel wood. Holocalyx is characterized by flowers with a nearly truncate calyx, an actinomorphic corolla of five petals, an androecium of ten stamens, and a stipitate gynoecium positioned centrally within the flower. There are two binomials in the genus: Holocalyx balansae and H. glaziovii. The first one was introduced with the description of the genus, but type material was not specified for the species. The latter, despite being a nomen nudum, is relatively widely applied in herbarium identifications. In this paper, we evaluate nomenclature within Holocalyx and present a taxonomic revision of the genus. We conclude that Holocalyx is monotypic, containing the single species H. balansae.