Five new clavate-stigma Waltheria species endemic to Brazilian Cerrado (Malvaceae s. l., Byttnerioideae, Hermannieae)

Abstract

Five new species are described and illustrated: Waltheria hatschbachii, W. hoehnei, both endangered for extinction, W. coriacea, W. flavovirens and W. matogrossensis. All are endemic to Brazil, in Cerrado s. l. associated with the Brazilian Plateau in N, NE, CW, and SE Brazil. Their affinities and the distinctness from W. ferruginea s. l. are discussed, and they are associated and compared with W. ferruginea s. str., from cerrado, W. brachypetala, from caatinga, W. biribiriensis and W. terminans, both from campo rupestre. The geographic distribution of all nine species is illustrated, and a new identification key for these and for the two sections of Waltheria is provided. All nine species share a clavate stigma in pin (or thrum) flowers, that morphotype given earlier as distinguishing one of three main species groups of the genus, and a new character, the ferruginea type stipitate-stellate trichome, illustrated here. Subconduplicate petals are first reported in the tribe Hermannieae, often keyed by flat petals. Waltheria is first signaled here to present the same enigmatic biogeographical pattern noted before for Triraphis (Poaceae) between Chapada dos Veadeiros, Africa and Australia. Other new taxonomic characters for Waltheria are given.