Edraianthus tarae (Campanulaceae), an intriguing taxon from the Balkan Peninsula: evidence from a morphometric and genome size study

Abstract

Edraianthus tarae, a taxonomically intricate stenoendemic plant species from the canyon of the river Tara (Montenegro), is reviewed using morphological and genome size data. Several morphological features distinguish this taxon from typical members of Edraianthus, which led to its segregation into its own genus, Protoedraianthus. Our formal morphometric analysis clearly indicates its morphological distinctiveness in relation to all other representatives of Edraianthus, supporting the idea of separation of this species into its own genus. However, our phylogenetic analyses, based on plastid DNA (trnL-F region and rbcL-atpB spacer) and nuclear ribosomal ETS sequences, revealed that although E. tarae forms an isolated lineage, positioned as a sister group to the rest of the E. graminifolius-complex, it makes a natural group within Edraianthus s.s. The genome size analysis largely corresponds with molecular results, further supporting the fact that, despite its morphological distinctiveness, E. tarae is clearly nested within Edraianthus and should be treated as congeneric. Given that the name Edraianthus tarae was not validly published, nomenclatural and taxonomical standings are discussed and re-evaluated. Edraianthus tarae is validated, a new differential diagnosis, description and illustrations are provided, and its conservation status is assessed.