Ertz, DamienElix, JohnGrube, Martin2015-12-102032-3913http://hdl.handle.net/1885/57787Background - A novelty is described in the framework of an ongoing revision of the Arthonia cinnabarina complex. Methods - Normal practises of herbarium taxonomy including high performance liquid chromatography (HPLC) have been applied. Key results - Arthonia borbonica is described as new to science. It is characterized by having ascomata covered by an orange pruina and macrocephalic (2-)3-septate ascospores. The species is only known from La Réunion island.Keywords: Arthonia; Arthoniaceae; Arthoniales; Ascomycota Arthoniaceae; Chemistry; Coniocarpon; La Réunion; Mascarene; Red pigments201010.5091/plecevo.2010.4272016-02-24