Sistemática de Hydrochorea Barneby & J.W.Grimes ( Leguminose, Mimosoideae)

Abstract

Hydrochorea is a Neotropical genus distributed in northern South America, occurring only in the Amazon and Cerrado domains. Belong the tribe Ingeae, its species have suffered several generic replacements throughout its history. Hydrochorea belongs to the "Alliance-Abarema" informal clade that also has the Abarema and Balizia genus, mainly differentiated by the type of fruit. The genus Hydrochorea is characterized by drupaceous loment fruit characteristic within the tribe, and rare in Mimosoideae. There are still many problems regarding the constituency of taxa currently subordinate to Hydrochorea. In this context, this paper aims to conduct the taxonomic study and the first attempt of the phylogenetic of Hydrochorea in order to show their infrageneric limits and the circumscription of their species as well as the relationships within the "Alliance-Abarema". In this work the "Alliance-Abarema" is strongly supported for two markers with Hydrochorea and Balizia in a polytomy, which together form the sister group of Abarema. Although Hydrochorea group is not resolved as monophyletic, length and support of the branches of this group is not high and the paraphyly of Hydrochorea regarding Balizia is not conclusive. New markers and population approaches should be tested to improve the resolution of this clade and clarify the relationship between these two genus. Hydrochorea is here circumscribed with five species and three varieties. Describes two new species and two lectotipifications are presented. Number of leaf jugae, prominent secondary veins, type and shape of the rachis extrafloral nectaries, flower bud, the shape of calyx in central flower and the presence or absence of this trichomes, were the character used in the separation of species. Taха grow predominantly in margin of rivers, floodplain forests and flooded forest, and areas where the seed can reach by dispersing the rivers. Further studies should be directed to countries like Venezuela, Bolivia, Guyana and Suriname and Brazil, in order to understand the ecology of these species in their natural habitat.