RESUMO
A smut fungus that hinders wiregrass restoration efforts in longleaf pine-grassland ecosystems was collected from Aristida stricta and A. beyrichiana (Poaceae) in three states in the southeastern USA. Morphological and phylogenetic characteristics of this fungus were examined. These data show that the specimens from both plant species were infected by the same fungus and represent a new species of Langdonia. The new species differs morphologically from other species of Langdonia by teliospores being solitary and not compacted into spore balls. Spore wall ornamentation and teliospore size also differ from other Langdonia species. Phylogenetic analyses of DNA sequences of the ITS, LSU, and EF-1α supported separation of the species from A. stricta and A. beyrichiana from other Langdonia species. Based on these results, a new species, Langdonia walkerae, is proposed.