On the Generic Circumscription of <I>Gonolobus</I> (Apocynaceae, Asclepiadoideae): Evidence from Molecules and Morphology

Abstract

Abstract Gonolobus (Apocynaceae, Asclepiadoideae) is a New World genus comprising an estimated 100–150 species. Variation in estimated species numbers is largely the result of still poorly known tropical taxa and differences regarding generic limits. Characters historically used to delimit genera such as Gonolobus within Gonolobinae—such as laminar dorsal anther appendages and various follicle morphologies—have been controversial and their evolution remains unknown, not having been explored in a phylogenetic framework. The primary objectives of the current study were to (1) test the monophyly of Gonolobus sensu Woodson in the context of a phylogeny of New World Asclepiadeae and (2) explore the evolution of laminar dorsal anther appendages and winged follicles with respect to their potential utility in generic circumscription. Chloroplast (trnL–F, rpsl6) data are newly presented for sixty-three taxa of Gonolobinae, representing an increased sampling of the subtribe from a maximum of seven taxa in prior stu...