The new species were discovered during a 12-year study with Conservation International, the CSIRO, Florida Museum of Natural History, the Indonesian Institute of Sciences and Indonesian Ministry of Marine Affairs and Fisheries.
According to Dr Christine Dudgeon, from the University of Queensland, the sharks are top predators on reefs during low tide, when they use their fins to walk in shallow water.
"At less than a metre long on average, walking sharks present no threat to people but their ability to withstand low oxygen environments and walk on their fins gives them a remarkable edge over their prey of small crustaceans and molluscs," Dr Dudgeon said.
"These unique features are not shared with their closest relatives the bamboo sharks or more distant relatives in the carpet shark order, including wobbegongs and whale sharks."
These new species occupy their own separate region in coastal waters around northern Australia and New Guinea.
"We estimated the connection between the species based on comparisons between their mitochondrial DNA which is passed down through the maternal lineage. This DNA codes for the mitochondria which are the parts of cells that transform oxygen and nutrients from food into energy for cells," Dr Dudgeon said.
"Data suggests the new species evolved after the sharks moved away from their original population, became genetically isolated in new areas and developed into new species," she said.
"They may have moved by swimming or walking on their fins, but it's also possible they 'hitched' a ride on reefs moving westward across the top of New Guinea, about two million years ago."
The researcher says they believe there are more walking shark species still to be discovered.
These four new species add to a total of nine known species of sharks that can walk.
