Ptychographa, a lichen genus new to North America

The genus Ptychographa is reported in North America from Oregon and Washington. Ptychographa xylographoides Nyl. is a lirellate crustose lichen that occurs exclusively on decorticate wood. The species is characterized by a dark brown to black exciple, simple spores, and a hymenium that is partitioned lengthwise. It grows at all levels in the canopy in old-growth conifer forests in the Cascade Range and has also been found on coarse woody debris in younger forests.