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Published: 2018-05-29

Idimanthus: A new aroid genus (Araceae—Caladieae) from Rio de Janeiro State, Brasil

Universidade Católica Dom Bosco, Curso de Ciências Biológicas, Av. Tamandaré 6000, Jardim Seminário, CEP 79119–900, Campo Grande – DF, Brazil
Atlantic forest geophyte rocky outcrop Monocots


The monotypic genus Idimanthus (Araceae-Caladieae), represented by the species Idimanthus amorphophalloides, is here described and illustrated. It differs from all Caladieae by its connective ending in a rostrate beak turned downward, but the combination of cormous geophytic stem, copious endosperm, densely arranged fertile flowers and sterile flowers densely arranged in an apical appendix did not match any other genera in the tribe. It was collected in a marble outcrop in Northern Rio de Janeiro state, in the county of Italva, nearby the city of Cardoso Moreira as an understory herb. The aspect of leafless inflorescences with a long apical staminoidal area appearing directly from the soil is remarkably peculiar for Southeastern Brazilian aroids.