Toward a new circumscription of Dombeya (Malvales: Dombeyaceae): A molecular phylogenetic and morphological study of Dombeya of Madagascar and a new segregate genus, Andringitra

Abstract

AbstractA phylogeny of Dombeya and near relatives is hypothesized from a combined analysis of five noncoding plastid markers and ITS using parsimony and Bayesian methods, and their taxonomy is evaluated by a synthesis of morphological observations with the molecular phylogeny. The topology of the combined analysis of all molecular markers generally corresponds with morphology and includes four major groups. The majority of the Malagasy species, a portion of Mascarene species, and all African species of Dombeya sampled form a monophyletic clade, which is defined as Dombeya s.str. A second clade includes those taxa with winged seeds: Helmiopsis, Helmiopsiella, D. linearifolia and the highly apomorphic Eriolaena. These data and morphology support the transfer of D. linearifolia to Helmiopsis. A third clade of D. subsect. Macranthae plus D. moratii is well supported by both morphological and molecular data; these taxa are segregated from Dombeya as the new genus Andringitra. The fourth clade contains Mascarene endemics: Trochetia, Ruizia, and a portion of the Dombeya from these islands. Two clades within Dombeya s.str. provide evidence against some currently recognized subsections within the genus that are based on inflorescence and androecial characters.