Morphological and anatomical evidence support a new wild cassava: Manihot fallax (Crotonoideae, Euphorbiaceae), from Mato Grosso, Brazil.

During the preparation of the taxonomic treatment of Manihot in the Midwest Region of Brazil, a new species was found. Manihot fallax M.J. Silva & L.S. Inocencio is described, illustrated and morphologically compared with similar simple-leaved species. The conservation status, geographic distribution (including map), ecology, phenology and notes about leaf anatomy of the new species are given. The synonymisation of M. robusta M. Mend. & T. B. Cavalc. under M. attenuata Müll. Arg. and lectotypes for M. attenuata and M. brachystachys Pax & K. Hoffm are also proposed. An emended description of M. attenuata is proposed as the original description is incomplete as it lacks information on the pistillate flowers, fruits and seeds.