The fossil record of testudinoid turtles of China during the Eocene-Oligocene is poorly documented. The Maoming basin is one of the few Paleogene basin in southern China having yielded a rich turtle fauna including Trionychidae, Carettochelyidae and Geoemydidae (Testudinoidea). Testudinoids were known in this basin by a single, supposed aquatic species, Isometremys lacuna CHOW and YEH, 1962. The examination of the new material collected since the first description, and a reexamination of the type material provide additional data on the morphology of that species. In addition, a second geoemydid, Guangdongemys pingi nov gen. nov sp., is described on the basis of shell material. Both species are supposed to be aquatic, and have a probably basal position in the geoemydid phylogeny.