The broadfin sawtail catshark (Galeus nipponensis) is a common species of catshark, part of the family Scyliorhinidae. It is found on or near the bottom at depths of , from southeastern Japan to the East China Sea. A slender species growing to long, this shark is characterized by a fairly long, pointed snout, a series of indistinct, dark saddles along its back and tail, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. In addition, adult males have very long claspers that reach past the anal fin. The broadfin sawtail catshark is an opportunistic predator of bony fishes, cephalopods, and crustaceans, with immature and mature sharks being primarily piscivorous. It is oviparous and reproduces year-round. Taxonomy The broadfin sawtail catshark has long been lumped together with the closely similar but smaller gecko catshark (G. eastmani), under whose name authors such as Toshiji Kamohara had described it since 1950. This shark was formally described as a new species in a 1975 volume of the scientific journal Memoirs of the Faculty of Fisheries, Hokkaido University by Kazuhiro Nakaya, who gave it the specific epithet nipponensis from Nippon (Japan). The type specimen is a long adult male caught off Mimase in Kōchi Prefecture, on December 20, 1972. Within the genus, this species is closest in morphology to the longnose sawtail catshark (G. longirostris). Distribution and habitat The broadfin sawtail catshark is found in the northwestern Pacific from Sagami Bay off southeastern Honshu, Japan to the East China Sea, including the Ryukyu Islands and the Kyushu–Palau Ridge. It is reportedly common in Japanese waters. This demersal species has been recorded from water between deep. Description Attaining a maximum known length of , the broadfin sawtail catshark has a slim, firm body and a head comprises less than one-fifth of the total length. The snout is rather long, flattened, and pointed, with large nostrils that bear triangular skin flaps on their anterior rims. The sizable eyes are horizontally oval and equipped with rudimentary nictitating membranes (protective third eyelids). Beneath each eye is a subtle ridge, and behind is a small spiracle. The capacious mouth forms a long, wide arch; well-developed furrows are present at the corners. The small teeth each have a narrow central cusp flanked by usually one, sometimes more, smaller cusplets on both sides. The five pairs of gill slits are short, with the last pair