In This Small Stream in Palawan, a New Goby Species Was Discovered
In a small and unpolluted stream that weaves through a forest in Palawan, tiny species of fish have managed to live hidden from humans and science, until now.
Japanese biologists from the Okinawa Institute of Science and Technology (OIST) and Filipino biologists from the Western Philippines University have found two new species of goby in Palawan: One from a small stream connecting to the Cayulo River in Palawan, and another in an estuary connected to the West Philippine Sea. The two new goby species are Rhinogobius estrellae and Rhinogobius tandikan. The scientists publisehd their discovery on Zootaxa.
Rhinogobius tandikan was found only in the Cayulo River, Bahile, which lies in the northern part of Puerto Princesa City. The Cayulo is a small stream stretching roughly four kilometers, including a one-kilometer stretch of an estuary. It flows into Ulugan Bay, which opens to the West Philippine Sea.
Rhinogobius estrellae is also endemic to Palawan Island. According to the researchers, most of the specimens were collected from a pool of a stream below the Estrella Falls located where a steep stream from Mt. Victoria comes out to a large plain in Narra, Sulu Sea-side of the island.
Very Surprising Discovery
This particular goby species was not expected to be found in Palawan, which is thought to be beyond the range of the fish.
Dr. Ken Maeda, first author of the study and staff scientist in the Marine Eco-Evo-Devo Unit at OIST, says the team was quite surprised of the discovery.
The Stream Where Rhinogobius tandikan Was Discovered
"We were very surprised the first time we saw Rhinogobius estrallae, and then really excited when we found the second species," said Dr. Maeda in a report by Phys.org.
"The Rhinogobius habitat is typically located in temperate and sub-tropical regions further north than Palawan, in places like Vietnam, China, Japan, and even the Russian Far East. Finding gobies from this genus in Palawan was very unexpected," he added.
Skinny, Battered Males
The scientists noted that males of the R. tandikan species appeared battered and skinny.
“We observed that males of R. tandikan were often skinny and almost always had heavy damages to the fins,” the authors wrote in their paper.
“They could be exhausted by caring for their nests and eggs, and the damage could be the result of fighting against conspecific males or against intruders to their nest during the spawning season.”
Threats to the Survival of the Species
Although the remoteness of the two species’ habitats could have played a role in their survival, the two species’ high level of endemicity or being found only in a very specific location could also pose a threat.
“Their endemic nature really raises the risk and threat level for both species,” said Maeda.
“Any disruption to their habitat, such as dams, roads, leisure facilities or development of the land for agriculture could quickly lead to their extinction.”
Ken Maeda, et al. (2022). “Two new species of Rhinogobius (Gobiiformes: Oxudercidae) from Palawan, Philippines, with their phylogenetic placement.” Zootaxa. Retrieved from https://mapress.com/zt/article/view/zootaxa.5068.1.3/45955 on 25 March 2022.
Dani Ellenby. (2022). “Two new species of freshwater goby fish discovered in the Philippines.” Phys.org. Retrieved from https://phys.org/news/2022-01-species-freshwater-goby-fish-philippines.html on 25 March 2022.