Petrova O. The lichen genus Usnea in eastern Gennoscandia. III Shrubby species. Ann. Bot. Fennici. 1999, 36, p. 235-256.

Ann. Bot. Fennici 36: 235–256 ISSN 0003-3847 Helsinki 14 December 1999 © Finnish Zoological and Botanical Publishing Board 1999 The lichen genus Usnea in East Fennoscandia. III. The shrubby species Pekka Halonen, Leena Myllys, Teuvo Ahti & Olga V. Petrova Halonen, P., Botanical Museum, University of Oulu, P.O. Box 3000, FIN-90401 Oulu, Finland Myllys, L. & Ahti, T., Department of Ecology and Systematics, P.O. Box 47, FIN-00014 University of Helsinki, Finland Petrova, O. V., Department of Flora and Vegetation, Polar-Alpine Botanical Garden, RUS-184236 Kirovsk, Murmansk Region, Russia Received 23 April 1999, accepted 18 October 1999 Halonen, P., Myllys, L., Ahti, T. & Petrova, O. V. 1999: The lichen genus Usnea in East Fennoscandia. III. The shrubby species. — Ann. Bot. Fennici 36: 235–256. Nine shrubby Usnea species are reported from East Fennoscandia: Usnea diplotypus Vain., U. fulvoreagens (Räsänen) Räsänen, U. glabrata (Ach.) Vain., U. glabrescens (Nyl. ex Vain.) Vain. ex Räsänen, U. hirta (L.) F. H. Wigg., U. lapponica Vain., U. sub- floridana Stirt., U. substerilis Motyka and U. wasmuthii Räsänen. New chemotypes are reported in U. glabrescens , U. substerilis and U. wasmuthii . Some chemotypes have geographical tendencies in their distribution. For instance, the thamnolic acid strain of U. subfloridana is the main chemotype of the species only in some southern coastal regions. Several poorly known taxa described especially by V. Räsänen are identified and lectotypified. A key to the shrubby Usnea species in East Fennoscandia is pro- vided. Key words: Finland, lichen, Russia, secondary chemistry, taxonomy, Usnea INTRODUCTION The Finnish lichenologist Edvard Vainio (e.g., Vainio 1925) laid the foundation for the taxonomy of the lichen genus Usnea Dill. exAdans. (Lecano- rales, Parmeliaceae) in northern Europe. Veli Rä- sänen (e.g., Räsänen 1919, 1931, 1933, 1951) was also much interested in the genus, describing nu- merous new species and varieties. His work was much influenced by the world monograph byMo- tyka (1936–1938, 1947), who cites numerous Finn- ish specimens. Finally Räsänen (1951) reported 34 species and eight varieties from Finland. Motyka’s and Räsänen’s species concepts were doubted by many authors (e.g., Keissler 1960, Klingstedt 1965), but because the taxonomy