Despite mycologists' interest in its unique spore-dispersal mechanism, systematic studies of the genus Sphaerobolus have received little attention. In our previous work multiple gene genealogies indicated the existence of three divergent lineages in the genus Sphaerobolus, each representing a phylogenetic species. Macro- and micromorphological analyses of colony and fruit-body characters presented here confirmed that these three phylogenetic species correspond to two known species, S. iowensis and S. stellatus, and a newly discovered species. In addition, an expanded gene genealogical analysis is presented for the three species. The new species, named Sphaerobolus ingoldii Geml, Davis et Geiser, is described based on both molecular and morphological data. In addition, while S. iowensis previously had been reported in only two localities, we found that it is as common as or more common than S. stellatus in North America. Despite the considerable amount of DNA polymorhism found in all species, nested clade analyses of S. iowensis and S. stellatus indicated little phylogeographic structure in either species, perhaps due to heavy movement mediated by human activities.