NEW SPECIES OR INTERESTING RECORDS OF FOLIICOLOUS LICHENS .3. ARTHONIA-CRYSTALLIFERA SPEC. NOVA (LICHENIZED ASCOMYCETES, ARTHONIACEAE), WITH A WORLD-WIDE KEY TO THE FOLIICOLOUS ARTHONIACEAE

A new foliicolous species of Arthonia from northern Argentina and Braz il is described: A. crystallifera L. I. FERRARO & R. LOCKING is distin guished from other foliicolous species of the genus by the presence of large, conspicuous, shiny crystals on the ascocarp surface. It is fur ther characterized by the brownish colour of its ascocarps, the macroc ephalic, 2-septate, colourless ascospores, and the radiate phyco-biont cells, indicating a close relationship to A. accolens STIRT. In order to facilitate the delimitation of foliicolous Arthoniaceae, a key to all hitherto known species (28) is presented. The new combination Erem othecella cingulata (R. SANT.) L. I. FERRARO & R. LOCKING comb. nova i s proposed (Bas.: Arthothelium cingulatum R. SANT).