, sp. nov., a newly described rust on the federally endangered plant, California sea-blite ().

Rust disease was observed on populations of near Morro Bay, California. The pathogen was identified as a species of based on teliospore and urediniospore morphology and nuc 28S rDNA sequence analysis. The isolate was compared with previously described species of that infect members of Chenopodiaceae, prompting a taxonomic reevaluation of species on . Herein, is described. It can be differentiated from the closely related (syn.: ) based on host range, teliospore morphology, and 28S sequence data. The new combination, , is made for , the oldest name for Eurasian rust. Finally, it was determined that likely does not occur in the United States and that the rust of in the United States likely comprises a third, yet unnamed taxon, different from both and . This is the first record of a rust fungus on . An identification key for species reported on Chenopodiaceae is provided.