Khaberni - Residents of southeastern Papua New Guinea have long known a strange fish capable of "walking" on shallow coral flats during tide, while most of its body remains out of the water for up to two full hours as it moves between coastal pools, a very rare ability among sharks.
The locals call it "Kadidikidikioa," which can be vaguely translated to "Dog Shark" or "Lazy Shark," referring to its slow, leisurely movement style within the shallow waters.
Now, scientists have identified this creature as a new, previously undescribed species, giving it the scientific name "Hemiscyllium dudgeonai" or "Dudgeon's Walking Shark," in honor of Christine Dudgeon, an ecologist at the University of Sunshine Coast in Queensland, Australia, who was part of the scientific team that formally described the species.
Researchers described the new species - the first to be added to the Hemiscyllium genus, also known as epaulette sharks, since 2013 - in a study recently published in the "Journal of the Ocean Science Foundation."
An Unexpected Encounter in Shallow Waters
Christine first spotted this shark after midnight on a day in March 2025, while diving in shallow waters only one meter deep over a seagrass meadow in Milne Bay, located off the southeastern coast of Papua New Guinea and facing the Solomon Sea.
Christine, who has dedicated more than 20 years to studying this genus of sharks, was swimming in search of another species of walking sharks known scientifically as Hemiscyllium michaeli or Spotted Epaulette Shark or Michael's Epaulette Shark, which is characterized by tiger-like markings, when she encountered a creature about one meter long gliding quietly along the sea floor.
When she directed her flashlight in front of it, it froze in place as a defensive reaction. She approached it gently, grabbed it, then flipped it onto its back and secured its tail under her arm, a method known as "tonic immobility," used to induce a temporary state of stillness in some sharks to facilitate handling.
A Clear Difference from Known Species
After securing the shark, Dudgeon handed it over to her colleague, chief researcher Jess Blakeway, who is also a marine biologist and a PhD candidate at the University of Sunshine Coast, and who was waiting nearby on a slowly drifting boat.
From the first moment, Jess realized that the shark's skin pattern and markings did not match those of other known walking sharks, which are quite similar in size and overall body shape as they all feed on small invertebrates living on the sea floor and pose no threat to humans. Therefore, scientists primarily rely on skin patterns, colors, and geographical distribution to distinguish between them.
Jess told Al Jazeera Net, "This species is distinguished by a unique pattern of short white lines and brown spots that reminded me of the Braille method or Morse code, a pattern clearly different from the rest of the species we work on and know within this genus."
This species belongs to a unique group of walking sharks that have developed a special ability to use their four pectoral fins as limbs for movement across the sea floor, allowing them to spend most of their time in shallow waters, where they swim between fields of seagrass and scattered coral clusters in Australia and the island of New Guinea.
Jess explains that "this feature is extremely useful in shallow coral environments, especially during low tide. By moving between isolated tidal pools as the tide recedes, these sharks can access prey that many other predators cannot."
Genetic Analysis Reveals the Identity
In the following days, the team continued searching for other individuals of this shark, and managed to catch an additional 11 individuals showing the same color pattern, which strengthened their confidence that they were dealing with a new species of shark not previously known to science.
However, proving that it was a new species could not be done based solely on external appearance. To confirm this, researchers collected biological samples from 9 individuals before releasing them back into their natural environment, while preserving three other individuals for detailed studies.
The researcher says, "Upon returning to the lab in Australia, we conducted DNA analyses that showed these sharks are genetically different from all previously described species within the Hemiscyllium genus."
She adds that "genetic analyses confirmed that Dudgeon's Walking Shark represents an independent lineage within the genus of walking sharks, and not just a color or shape variation of a previously known species, confirming its status as a new independent species scientifically."
Limited Range of Spread
Although scientists are still in the early stages of studying this species, they believe it has the smallest known geographical range among all discovered walking shark species, which generally have restricted living ranges, making them more sensitive to local threats.
Jess points out that Papua New Guinea is one of the richest regions in the world in terms of biodiversity, yet accessing many of its areas poses significant logistical challenges. Consequently, vast areas of it remain unexplored scientifically and have not been subject to regular field surveys.
Samples were collected between the Amphlett Islands and the Trobriand Islands located north of Milne Bay. However, researchers expect this species to be spread across the D'Entrecasteaux and Trobriand Islands, and possibly extend to Muyuw Island, located approximately 274 kilometers northeast of Milne Bay.
Jess says, "Our current knowledge of the geographical distribution of Hemiscyllium dudgeonai is based on field surveys conducted in Milne Bay and Oro provinces, in addition to historical observations and available photographic records. Nevertheless, more studies are needed to determine its full range accurately."
She adds that "while this discovery adds a new species to the exceptional biodiversity that Papua New Guinea boasts, especially in the Milne Bay area, it also highlights how little we still understand about the biodiversity in this region. More importantly, it raises new scientific questions about the mechanisms that led to the emergence of new species and their differentiation in this biologically rich area."
She continues, "One of our main priorities is to determine the full geographical range of the species more accurately, understand the nature of the threats it faces, study the effectiveness of existing local management systems, such as locally managed marine areas, and understand how much they contribute to protecting and preserving this species."
Fears of Extinction Risk
Although scientists have only recently identified this unique species of walking sharks, the discovery immediately raised serious concerns about the fragility of this new species' situation and its likelihood of survival, as they believe it may face local extinction unless urgent and effective protection measures are taken.
This species faces a range of environmental threats, including natural habitat degradation due to urban expansion and coastal development, coral bleaching associated with climate change, and pressures from local fishing activities and the expanding range of oil palm plantations and accompanying environmental pressures.
Given its limited range of spread compared to other walking shark species, this species is likely the most endangered among all known species in this group.
The study suggests that the new species may have already disappeared from some locations where it used to live, a situation scientifically known as "local extinction," meaning the disappearance of the species from a specific area while remaining in others.
The researcher mentions that "locals in several areas have reported that walking sharks have become rarer and harder to spot compared to the past, raising concerns about the possibility of local extinction in some locations or a decline in population numbers of the species."
Before this discovery, scientists recognized only 9 species of walking sharks. The International Union for Conservation of Nature classifies two of them as "endangered," including the Spotted Epaulette Shark that the team was originally searching for when they found the new species.
Jess and her team hope to return to the area later this year to continue studying Hemiscyllium dudgeonai. According to her, this will require continuing field surveys and working closely with local communities to document the presence of the species and the impact of environmental pressures and human activities on it.
The new data could support classifying this species as endangered in the future when officially assessed.
Based on current data, Jess believes the species meets the criteria of Criterion B, associated with the narrow geographical range of the species, adopted by the International Union for Conservation of Nature. Therefore, it may be eligible for classification as "endangered" or "critically endangered." However, she points out the need for more data to support any official assessment.
