The recently revised Geastrum minimum species complex in sect. Geastrum subsect. Quadrifida revealed that the name G. minimum is a nomen ambiguum and dubium and was collectively used for at least two European species (viz. G. granulosum and G. marginatum). During the morphological revision of the Hungarian materials labelled as G. minimum, different crystal structures were found on the endoperidial body of some specimens than those of characteristic for G. granulosum and G. marginatum. These collections were exclusively found on open rocky grassy vegetation on dolomite bedrock in Hungary. Multigene phylogenetic analyses involving nrITS, nrLSU, rpb1, atp6 and tef1-α sequences of the collections with unique crystal morphology and ecology revealed that these form a distinct clade in close relationship with G. granulosum s.l. (i.e. specimens from Europe and North America). Based on molecular evidence, macro- and micromorphology as well as X-ray Powder Diffraction (XRD) characterisation of the mesoperidial crystals, here we propose the new species Geastrum dolomiticum.