Five new crustose Stereocaulon species in western North America

Abstract

Crustose Stereocaulon species have only recently been reported from North America, and targeting them specifically in recent fieldwork revealed an unexpected diversity of species. We sampled crustose Stereocaulon species in western North America from Alaska to Oregon and analyzed them by morphology, DNA sequencing, and thin-layer chromatography. Five new species were found, along with one species known from northern Europe and North America (S. leucophaeopsis), a second one previously known only from northern Europe and eastern North America (S. plicatile), and one previously known western North American endemic (S. nivale). Each of these species is supported by DNA sequences, as well as morphological and chemical characters, such that they can be distinguished by simple spot tests and morphology. One exception is that S. leucophaeopsis and S. areolatum may be difficult to distinguish when sterile without a DNA sequence. The number of crustose Stereocaulon species known from North America is increased from 3 to 8. Seven of those eight species occur in the national parks of southwestern Alaska (Katmai, Lake Clark, and Kenai Fjords). Two of the eight are known from Oregon and Washington.