The freshwater shrimp family Kakaducarididae Bruce, 1993 is revised and its familial status reappraised using morphological characters and the results of a complementary molecular study (Page et al. 2008). Based on combined morphological–molecular data, the Kakaducarididae is synonymised with the Palaemonidae Rafinesque, 1815 and the monotypic genus Kakaducaris Bruce, 1993 is synonymised with Leptopalaemon Bruce & Short, 1993. The Texan cave shrimp, Calathaemon holthuisi (Strenth, 1976), provisionally included in the Kakaducarididae by Bruce (1993), is re-assigned back to the Palaemonidae. Leptopalaemon is re-diagnosed and three new species, L. gibbosus, sp. nov., L. gudjangah, sp. nov. and L. magelensis, sp. nov., are described from the north-western edge of the Arnhem Land plateau/escarpment complex, Northern Territory, Australia. The two previously described species, L. gagadjui Bruce & Short, 1993 and L. glabrus (Bruce, 1993), comb. nov. are re-diagnosed. A key to the five presently recognised Leptopalaemon species is provided.