NEW SPECIES AND NEW COMBINATIONS IN THE LICHEN GENUS PHYSCONIA IN NORTH-AMERICA

Four new species in the lichen genus Physconia are described from Nort h America. Physconia americana Essl. from western North America, and P h. subpallida Essl. from eastern North America, are primary species wh ich had previously been mistaken for Ph. distorta (With.) Laundon. The other two species are both from western North America: Ph. thomsonii Essl. is a sorediate species resembling and previously mistaken for Ph . grisea (Lam.) Poelt and Ph. elegantula Essl. is an isidiate species. Two new combinations are also made: Ph. leucoleiptes (Tuck.) Essl. an d Ph. isidiigera (Zahlbr. in Herre) Essl.