Rock lobsters ofJasussubgroup"lalandifin New Zealand(Jasus edwardsii(Hutton, 1875)) and south‐eastern Australia (J. novaehollandiaeHolthuis, 1963) are biologically similar and gene flow is possible. The variation between Australian populations, and overlap with the New Zealand population, in morphology, colour, and biochemical genetics, and the agreement in life‐history characters, make it impossible to distinguish animals from the two countries. The New Zealand and Australian populations of rock lobster should therefore be referred to as a single species, which by priority isJ.edwardsii.The long‐lived phyllosoma larval stage is widespread in the central and south Tasman Sea. Rates of any larval recruitment in New Zealand from animals spawned in Australia are likely to be variable because of variability in flow in the Tasman Sea, and because of the distance involved.