New molecular evidence for Canarian endemic Ruta (Rutaceae: Ruteae) reveals a complex evolutionary history and overlooked diversification processes.

This article focuses on the genetic variation, evolutionary history, and taxonomic delimitation of four currently recognized endemic Ruta species (Rutaceae) from the Canary Islands, a noted oceanic biodiversity hotspot. Using four plastid DNA regions and extensive population sampling across Gran Canaria, Tenerife, La Palma, and La Gomera, the study reveals a complex pattern of colonization and diversification dating from the late Pliocene to the Pleistocene. Results show that Ruta oreojasme from Gran Canaria diverged earlier than its congeners, with multiple secondary colonization events between and within islands shaping the diversification of Ruta pinnata and Ruta microcarpa; the recently described Ruta nanocarpa on La Gomera is genetically distinct but closely related to R. microcarpa. The high genetic differentiation detected challenges current taxonomic circumscriptions, suggests ongoing diversification, and highlights the need for urgent, population-level conservation efforts, particularly for the single population of R. nanocarpa on La Gomera and genetically distinct populations from La Palma and Tenerife's palaeo-islands.