Resolving the Sticta fuliginosa morphodeme (lichenized Ascomycota: Peltigeraceae) in northwestern North America

Sticta is a subcosmopolitan, predominantly epiphytic lichenizing fungal genus characteristic of open sites in humid late-successional ecosystems. Recent molecular analysis has shown that the laminally isidiate species S. fuliginosa, long assumed to be well delimited, encompasses >20 phylospecies which, taken together, constitute the S. fuliginosa morphodeme. Here we elucidate the northwestern North American members of this morphodeme based on a rich sampling from throughout the Pacific Northwest regions of the U.S.A. and Canada: Alaska, British Columbia, California, Oregon and Washington. Our results support recognition of five species, three of which - S. arenosella sp. nov., S. fasciculata sp. nov. and S. torii - appear to be endemic. Of the remainder, S. globulifuliginosa was described from Colombia, while S. gretae sp. nov. occurs also in the Canary Islands and China. Two of our new species - S. fasciculata and S. gretae comprise a new phylogenetic lineage and is referred to as the S. gretae clade. New taxonomically informative thallus characters are introduced and a key to the genus Sticta in northwest North America is provided.