Recent collections from southeastern North America prompted a revision of Gyalideopsis ozarkensis and G. subaequatoriana. The protologues and original material of these names are shown to comprise elements of three seemingly allopatric taxa that can be recognized based on differences in diahyphae morphology that appear to be correlated to different biogeographic patterns. Gyalideopsis ozarkensis is restricted to specimens with long multi-septate diahyphae from the Ozarks, Ouachitas, and the southwestern Appalachian Mountains. Gyalideopsis subaequatoriana is restricted to collections from tropical central Florida with moniliform diahyphae. A third species, G. bartramiorum, is described as new to science for material from the Mid-Atlantic Coastal Plain and southern Appalachians Mountains. All three taxa are illustrated and maps of their geographic distributions are presented.