A new species of Antherospora supports the systematic placement of its host plant.

The morphology and phylogeny of anther smut specimens on Tractema verna collected in the United Kingdom were investigated using light microscopy, scanning electron microscopy and partial rDNA sequence analyses. The anther smut of Tractema verna shows similarity to Antherospora eucomis, A. scillae, A. tourneuxii, A. urgineae, A. vaillantii, and A. vindobonensis but differs in spore size range, spore wall thickness, host plant genera and considerable divergences of ITS and LSU sequences. Consequently, the smut is described here as a new species, Antherospora tractemae. The host plant was formerly included in the genus Scilla (S. verna), but recently moved to a distinct genus Tractema. Molecular phylogenetic analyses reveal that Antherospora tractemae is sister to the lineage of Muscari-parasitizing Antherospora and only distantly related to the Scilla-parasitizing Antherospora species. Thus, the phylogenetic placement of the smut fungus supports the systematic placement of its host plant.