The deepwater catsharks that make up the genus Galeus are members of the family Pentanchidae.
Due to the fact that it has about 20 distinct species, it is considered to be one of the most species-diverse genera of sharks.
The Gulf of California, the western and central Pacific Ocean, and the Atlantic Ocean are all home to individuals belonging to this species.
They are often referred to as sawtail catsharks because of a unique saw-toothed crest of enlarged dermal denticles that can be observed along the top edges of their caudal fins. This crest can be found along the back of the animal.
They have bodies that are solid and thin, and their skin is thick and rough. They are harmless and rather small. Their heads are often somewhat elongated and tapered, and they have large mouths with well-developed furrows at the corners. A great number of species have patterns that may include dark saddles and/or spots.
They consume a wide variety of fishes and invertebrates for food, and they either lay eggs or give birth to live young.
Galeus is distinguishable from other members of the Pentanchidae family by a combo of its color pattern of blotches and patches, relatively large pectoral fins, as well as the absence of expanded denticles along the ventral surface of the caudal peduncle according to marine biologists David Ebert and Jessica Jang of the Pacific Shark Research Center. These increased denticles are characteristic of sharks of the genus Figaro.
The genus is widespread, with the majority of its sightings occurring on outer continental shelves and slopes, as well as on insular slopes between 100 and 2,000 meters in depth.
Galeus friedrichi, more often known as the Philippines sawtail catshark, is only known from the type specimens that were taken at a depth of 550 meters off the coast of Sikayab-Bukana in the Philippines.
It is the third species of the genus Galeus to be discovered in the Philippines; Galeus schultzi is exclusive to the archipelago, and Galeus sauteri can also be found off the coast of Taiwan.
It is distinguishable from all other regional congeners by the absence of saddle or blotch patterns on the body and caudal fin; its large size, which exceeds 50 cm in total length; and its higher count of monospondylous vertebrae and precaudal vertebrae. These characteristics combine to make it possible to identify this species.
The researchers said that since 2002, about one-quarter of all chondrichthyans have been described.
Over the past 20 years, there has been a boom in the study of chondrichthyan taxonomy, which has resulted in the discovery of a large number of new species that would not have been able to be categorized on the IUCN Red List otherwise.
In fact, three of the nine sawtail catsharks that are addressed in this research have only received their proper names within the previous 15 years.
Many of these discoveries, including the newly described species, are deep sea species. This highlights how much more there is to be discovered in this environment, particularly as fisheries internationally extend into the deep sea.
Sources:
D.A. Ebert & J.J. Jang. (2022). Galeus friedrichi (Carcharhiniformes: Pentanchidae), a new sawtail catshark from the Philippines. Journal of the Ocean Science Foundation 39: 45-53; doi: 10.5281/zenodo.7320085. https://zenodo.org/record/7320085
