A new species of the genus Allocyclops Kiefer, 1932 (Cyclopidae, Cyclopinae) is described from the subterranean waters of Barrow Island, Western Australia. It belongs to the subgenus Psammocyclops Kiefer, 1955, but has not any close relatives among the recent known species. With the addition of the new representative the genus Allocyclops now includes thirteen species on all continents, except Asia and Antarctica. A key to aid in their identification is provided.