NEW CIRCUMSCRIPTION OF ABAREMA (LEGUMINOSAE)

¹Ethiéne Guerra, ¹Marcos Vinícius Batista Soares, ²Marli Pires Morim & ¹João Iganci

¹Programa de Pós-Graduação em Botânica, Departamento de Botânica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil. ²Instituto de Pesquisas do Jardim Botânico do Rio de Janeiro, Rio de Janeiro, RJ, Brasil. [email protected]

The genus Abarema Pittier was described in 1927 based on Pithecellobium sect. Abaremotemon sensu Bentham of 1844. Since then, Abarema had many different taxonomic circumscriptions, incorporating and losing species, and showing different positions in relation to other close related genera. The genus is classified into the tribe Ingeae, within the informal group Abarema Alliance. In 1996, Barneby and Grimes advertised that the limits between Abarema and close related genera of the tribe Ingeae were still not well determined. A recent molecular phylogenetic study based on a large species sampling of the Abarema Alliance, showed that the genus type species, Abarema cochliacarpos (Gomes) Barneby & J.W.Grimes, is separate from the others Abarema species. Besides this, the species is positioned within Inga Alliance. Abarema cochliacarpos is an endemic species from Brazil, occurring in two biomes, the Atlantic Forest and the Cerrado. Lewis et al., in 1987, mentioned the occurrence of two morphotypes of Abarema cochliacarpos in Bahia state. Iganci et al., in 2012, also recognized other two morphotypes for the species in different regions of Rio de Janeiro state. For providing a robust new circumscription of Abarema, based on Abarema cochliacarpos, and for recognizing if each morphotype do represent different species or not, we realized a large revision on the herbaria data and an extensive field work, covering the total distribution of A. cochliacarpos. The qualitative diagnostics characters that we present to recognize Abarema are: branches with pubescent and ferruginous pulverulent indumentum, with conspicuous lenticels; nectaries sessile, orbicular, pateliform, between the pairs of pinnae and leaflets; capitate raceme; flowers pentamerous, calyx with margin ciliate, corolla with margin ciliate; spiralled pods, epicarp pulverulent, ferrugineous; seeds bicoloured, with open median-basal pleurogram; embryo cryptoradicular; plumule developed, differentiated in leaflets. In relation to the morphotypes studied, we recognized a clearly morphologic distinct group in the Cerrado, which comprises a new species. Our results show that the new circumscription of Abarema is based in robust morphological characters, and that Abarema sensu stricto is not a monotypic genus, comprising, at least, two species, Abarema cochliacarpos and Abarema sp new. (CNPq)

Keywords: Fabaceae, morphological characters, morphotypes, new species.