Sirococcus conigenus, Sirococcus piceicola sp. nov. and Sirococcus tsugae sp. nov. on conifers: anamorphic fungi in the Gnomoniaceae, Diaporthales

Summary Sirococcus is a genus of asexually reproducing fungi that includes important pathogens causing shoot blight and tip dieback of conifers. In this paper, the type species of Sirococcus, S. conigenus , is redescribed and illustrated, and an epitype designated. In addition, two new species are recognized. Sirococcus piceicola sp. nov. is described from species of Picea in Canada and Switzerland. A second new species, S. tsugae sp. nov., is known only from western North America on species of Cedrus and Tsuga. These three species can be distinguished based on morphological differences and molecular sequence data from four genes. The three species of Sirococcus on conifers vary in conidiomatal wall structure, shape of the conidiogenous cells, and shape and size of conidia.