Molecular and morphological evidence for a new seed-destroying smut fungus, Microbotryum graecum on Stellaria media from Greece

The group of seed-destroying Microbotryum species on caryophyllaceous hosts includes ten species, among which only M. alsines, on Stellaria nitens from USA, is known on Stellaria. Recently, a specimen of Stellaria media from Greece, infected by a seed-destroying Microbotryum species, was found in a phanerogam herbarium. Based on distinct morphology and phylogenetic evidence, this fungus was considered to represent an unknown species which is described and illustrated as Microbotryum graecum. It can be distinguished from M. alsines by having smaller spores, fewer meshes per spore diameter, a different spore ornamentation, wider meshes, and higher spore wall muri.