A synopsis of the genus Gomphillus in the Americas is presented, with the description of the new species, G. pedersenii L. I. Ferraro & Lücking, from Argentina. The new species is characterized by pale, vertically elongate apothecia, rather broad ascospores, and umbelliform hyphophores. With the exclusion of G. caribaeus W. R. Buck, which belongs in a new genus, Bryogomphus, in the Pilocarpaceae, and the recent discovery of another new species, G. morchelloides Lücking & Sérus., the genus Gomphillus now comprises five species. All taxa are keyed out and briefly discussed, and a distribution map for the Americas is given.