The identity of Buellia sequax

Abstract

The study of the type specimens of Buellia sequax revealed that the current concept of this species is erroneous and instead corresponds to B. abstracta. By contrast, B. sequax s. str. is characterized by the same diagnostic characters as presently accepted for B. excelsa. Consequently, they represent one and the same taxon. Since B. sequax is the older name, B. excelsa is reduced to synonymy. Buellia lepidastroidea is also reduced to synonymy with B. sequax s. str. Buellia sequax s. str. (= B. excelsa and B. lepidastroidea) contains diploicin and atranorin, has a hymenium inspersed with oil droplets, and ascospores which develop with type-B ontogeny. This combination of characters suggests that B. sequax s. str. is closely related to the genera Diploicia and Endohyalina but B. boergesenii does not belong to this group. New data on the chemistry and distribution of B. sequax s. str. are provided and amended descriptions of this species and B. abstracta (= B. sequax auct.) are presented.