Usnea viktoriana (Ascomycota, Parmeliaceae), a new European taxon of the Usnea barbata - dasopoga group, with a key to the shrubby-subpendulous sorediate Usnea species in Europe.

Usnea viktoriana P. Clerc & Otte is described as new. It is characterized by the presence of alectorialic acid as major secondary compound mainly present in the aggregated efflorescent soralia with long isidiofibrils. Usnea parafloridana K. Mark, Will-Wolf & Randlane is synonymized with U. praetervisa (Asahina) P. Clerc. Both U. viktoriana and U. praetervisa are supported by molecular analysis. A key to the shrubby-subpendulous sorediate Usnea species in Europe is provided. [ABSTRACT FROM AUTHOR]