The authors acknowledge a great debt to Professor
J. D. Rogers (WSU, USA) for his constant support and his valuable
help to this project, and for his critical review and judicious
comments. Dr. M. Stadler (Bayer, Wuppertal, Germany) is gratefully
acknowledged for his friendly collaboration, for his invaluable informations
and comments on the chemotaxonomic part and his precious help with literature.
Special thanks to Dr. A. Granmo (Troms, Norway), F. Candoussau,
P. Leroy, G. Gilles and J. Vivant (France)
for having sent the collections quoted in the taxonomic part.