Two new species of phreatoicidean isopods from artesian springs in southwestern Queensland are described. These taxa have been shown to form a clade that is distinct from all other taxa in the suborder. Therefore, a new genus, Ponderella, and a new family, Ponderellidae, are established for this clade. These two epigean species share many features in common with the hypogean family Hypsimetopidae but lack their derived features, such as elongate bodies or curved claw-like uropodal endopods. Both new species share an enlarged fourth article of the antennula, a synapomorphy that occurs in no other phreatoicidean. Their pleotelsons are also distinctive in having relatively unelaborated posterior margins that are indented at the apices. The two species differ in several morphological traits that vary at the generic level or higher in other families of the Phreatoicidea: size of the lacinia mobilis on the right mandible; distinctive modifications of the male pereopod IV in one of the species; presence or absence of propodal articular plates on the posterior pereopods; presence or absence of the pleopodal lateral epipods; and shape
of the pleotelson in lateral view. These species occur sympatrically in two adjacent localities in the Eulo mound springs supergroup. Because of their restricted distribution in habitats that lack environmental protection, these species are potentially endangered.