Caloplaca stantonii sp. nov. and its relationship to Caloplaca bolacina and other lobate to squamulose species in North America

Caloplaca bolacina (Tuck.) Herre and C. stantonii sp. nov. belong to a group of species in North America with more or less lobate, subsquamulose to squamulose thalli. The two species occur mainly on rocks in the coastal mountains and on maritime rocks in western North America. Caloplaca bolacina is here lectotypified and provided with a thorough description. Caloplaca stantonii, sometimes confused with C. bolacina, was in 1989 distributed in Lich. Exs. Colo No. 672 by W. A. Weber but is described for the first time in this paper. The present study was carried out to clarify the taxonomy of C. bolacina and C. stantonii and their relationship to a group of similar species. This group, here referred to as the C. squamosa group, comprises many species, both European and American. A key to the treated taxa is included. The taxonomy within the C. squamosa group is not dealt with. The results show that C. bolacina, C. stantonii, and the C. squamosa group are separated from each other principally in several anatomical characters as well as in gross morphology.