The genus Cryptosphaeria in the western United States: taxonomy, multilocus phylogeny and a new species, C. multicontinentalis

This study investigates the diversity and taxonomy of Cryptosphaeria species occurring in the western United States on the basis of morphological characters and multilocus phylogenetic analyses of the ribosomal internal transcribed spacer region, parts of a β-tubulin gene, the DNA-dependent RNA polymerase II second-largest subunit gene and the nuclear ribosomal large subunit gene. Cryptosphaeria multicontinentalis sp. nov is described from the Sierra Nevada and central coast of California on Populus tremuloides, P. balsamifera subsp. trichocarpa and P. fremontii. Cryptosphaeria pullmanensis is reported from a wide geographic area in the western United States on the main host, P. fremontii. The pathogen C. lignyota is reported for the first time from the Sierra Nevada of California on P. tremuloides. The phylogenetic analyses showed that C. multicontinentalis is a sister species to C. lignyota. Both species were closely related to C. subcutanea and more distantly related to C. pullmanensis. Characteristics of both teleomorph and anamorph of the newly introduced species C. multicontinentalis are described and illustrated.