Astartoseris (Cichorieae, Asteraceae), a new, systematically isolated monospecific genus accommodating lactuca triquetra endemic to Lebanon and Cyprus

Abstract

The taxonomy of Lactuca triquetra, a scoparious subshrub of localized distribution and uncertain generic placement, is assessed. The taxon was described in the early 19th century from Lebanon and more than 100 years later also discovered on Cyprus. Referring to new molecular phylogenetic results published elsewhere, morphological characters, in particular of the achenes, are reconsidered. It is inferred from the available evidence that the diploid species represents an orphan lineage, which diverged from its ancestors already in the Middle Miocene, when the Cichorieae subtribes Crepidinae and Lactucinae started diversifying. Both molecular and morphological data indicate that the species holds a position mediating between both subtribes. The taxonomic conclusion is drawn to place the species in a new genus of its own, Astartoseris. The taxon is illustrated and a comprehensive description, distribution map and brief ecological characterization are provided. Its threat status in both countries is assessed for the first time.