Chrysothrix bergeri (Ascomycota: Arthoniales: Chrysothricaceae), a new lichen species from the southeastern United States, the Caribbean, and Bermuda

A crustose lichen species new to science – previously characterized in the literature but unnamed – is formally described. This new species, Chrysothrix bergeri sp. nov., ranges from the southeastern United States southwards to the Caribbean islands (Bahamas and Cuba) and eastwards to Bermuda. It is most easily confused with C. xanthina, from which it differs in both chemistry and ascospore shape. Bilimbia aurata and Bilimbia stevensoni are both confirmed as synonyms of C. xanthina. A lectotype is selected for Bilimbia aurata. Solvent E is recommended for the chromatographic separation of leprapinic and pinastric acids – two lichen secondary products critical for diagnosing certain species of Chrysothrix, including C. bergeri.