Does the current taxonomic delimitation of Galianthe find support in phylogenetic perspective?

FLORENTIN, J.E:; NUÑEZ FLORENTIN, M.; PÉREZ, M. L.; ESPASANDIN, F

Misiones

Conferencia; VIII International Rubiaceae and Gentianales Conference; 2023

Galianthe Griseb. is a neotropical genus comprising 50 species divided into two subgenera: G. subgen. Galianthe (41 spp.), characterized by homogeneous morphological traits, with species further divided into two sections (G. secc. Galianthe and G. secc. Laxae); and G. subgen. Ebelia (14 spp.) with more heterogeneous morphological characteristics. Due to morphological similarities with other genera, Galianthe has historically been associated with Borreria, Spermacoce, Diodia (based on fruit type), as well as Denscantia and Emmeorhiza (based on inflorescence type). In recent years, molecular studies have established Galianthe as a basal genus within the clade, closely related to other genera such as Carajasia and Schwendenera. Despite molecular advancements, recent studies have focused on a limited number of species within the genus, failing to encompass all infra-generic categories. To challenge the current taxonomic delimitation of the genus, this study aims to test the monophyly of Galianthe and explore its infra-generic and interspecific phylogenetic relationships. Three markers (two nuclear: ITS, ETS, and one plastidial: rps16) were utilized, encompassing 107 entities, including 42 Galianthe species, thereby representing 76% of the current genus diversity, as well as 17 related genera within the Spermacoce clade. The phylogenetic results confirm the monophyly of Galianthe, revealing the presence of three major subclades. Subclades I and II comprise several G. subgen. Ebelia species, whereas subclade III consists of all G. subgen. Galianthe species plus G. angulata. Regarding the sections, monophyly was not supported. Based on these findings, it can be concluded that G. subgen. Ebelia is paraphyletic, G. subgen. Galianthe is potentially paraphyletic due to G. angulata, and there is no clear distinction between the sections.