A revised classification of Glossopetalon (Crossosomataceae) based on restriction site-associated DNA sequencing

Glossopetalon inhabits arid regions in the American west and northern Mexico on limestone substrates. The genus comprises four species: G. clokeyi ; G. pungens ; G. texense ; and G. spinescens . Three of the species are narrow endemics. The fourth, G. spinescens , is a widespread species with six recognized varieties. All six varieties are intricately branched shrubs that have been difficult to identify due to a lack of clearly delineating morphological characters. Characters typically used to differentiate the varieties of G. spinescens, such as stem coloration, leaf blade size, and presence of stipules, are highly variable within and among populations. A custom protocol of double digest restriction-site associated DNA sequencing (ddRAD) was used to resolve the phylogeny of Glossopetalon and address if population genetic data analyses (such as STRUCTURE, SVDquartets, and phylogenetic networks) support the recognition of six varieties of G. spinescens . Glossopetalon ...