The genus Metastelma (Asclepiadoideae-Asclepiadeae-Metastelmatinae) in South America

Abstract

Molecular and morphological analyses are used to circumscribe the genus Metastelma in South America. In northem South America, fourteen species are identified, nine o f them new; and two species are found in Southern South America, one o f them new. The northem South American lineage is retrieved as sister to a clade comprising the type species of Metastelma, M. parviflorum, one o f several Caribbean lineages. The Southern South American lineage remains unresolved. The Central American lineage remains poorly supported monophyletic, but ineludes a species from Jamaica, M. priorii. Several specimens from the Andes o f Argentina and Bolivia are retrieved in a well-supported clade outside Metastelma s.s. For these specimens, a new genus is described comprising presently seven species. Four o f these species are transferred from Metastelma, one from Ditassa, and two species are described as new Stelmation E.Foum. is resurrected, comprising presently a single species, S. myrtifolium from Brazil. Metastelma giuliettianum and M. harleyi, also from Brazil, are excluded from Metastelma, but cannot yet be transferred to another genus, because the taxonomy o f Metastelmatinae is still in flux. Thus, Metastelma s.s. is absent from Brazil.