A Critical Appraisal of Modern Generic Concepts in Lichenology

Abstract

After a brief historical survey, some current trends in the delimitation of lichen genera are discussed. A widespread tendency is that of elevating any supposedly monophyletic group of species to genus rank. As the term ‘ monophyletic ’ has no lower limit, this is likely to result in an explosive inflation of new genera, in a severe loss of the information carried by generic names and in a high degree of nomenclatural disorder. Five criteria are proposed for the acceptance or rejection of new generic segregates: (1) DNA testing for monophyly, (2) phylogenetic analysis, (3) number of characters used, (4) number of species considered, (5) information content of the new splittings. Upon a critical analysis of several recent generic segregations, a more flexible approach to taxonomic ranks is recommended, and particularly, when most of the suggested criteria are not fulfilled, a more frequent use of the subgeneric rank, which does not imply name changes.