New and endemic species of Sida sect. Ellipticifoliae (Malvaceae, Malveae) from Brazil and an updated key to the species of this section

On some expeditions, some unusual Sida specimens were found and collected in open vegetation amid fragments of Atlantic Forest in the Brazilian state of Paraíba, in the far east of the Americas. The discovery inspired some detailed studies into the morphology of these specimens and resulted not only in the recognition of a new species of Sida, but also in the first record of a native specimen of section Ellipticifoliae Fryxell for Brazil. Sida ellipticifolia, as described and illustrated here, is the tenth species of the section and has morphological affinities with S. littoralis Siedo, a species from the coast of Florida. Although geographically well separated, they share morphological and ecological similarities, but the new species differs by the simple trichomes mixed in the indumentum of the stem and branches, the obtuse base of the leaf, the pedicel articulated, the diamond-shaped sepals and the apical portion of the schizocarp not emerging from the calyx, which are the most distinctive characters. The discovery reaffirms Brazil as one of the centres of native diversity of Sida, an eumalvoid taxon of Australasian pre-origin. Description, illustrations and an updated identification key for section Ellipticifoliae are provided along with notes on ecology and conservation.