The longhead catshark or smoothbelly catshark (Apristurus longicephalus) is a species of catshark, family Scyliorhinidae, with a patchy distribution in the Indo-Pacific from Mozambique to southern Japan to northern Australia. It is found in water between deep. This species grows to long and is characterized by its extremely long and narrow snout, short abdomen, and long anal and caudal fins. In addition, a large area of the anterior ventral portion of its body lacks dermal denticles. The longhead catshark is oviparous and the only known cartilaginous fish that is normally hermaphroditic, with the majority of individuals having both the functional reproductive organs of one sex and the undeveloped reproductive organs of the opposite sex. Taxonomy and phylogeny The first known specimen of the longhead catshark was captured in Tosa Bay, Kōchi Prefecture, Japan, on May 12, 1972. The 38-cm-long specimen was initially thought to be an immature male, but has since been identified as a functionally female hermaphrodite. The new species was described by Kazuhiro Nakaya in a 1975 volume of the scientific journal Memoirs of the Faculty of Fisheries, Hokkaido University. In 1999, Nakaya and Sato grouped this species with the similarly long-snouted longfin catshark (A. herklotsi) in the A. longicephalus species group. Distribution and habitat Records of the longhead catshark are patchy and widely spread in the Indo-Pacific region: it is known from the East China Sea, southern Japan, the Seychelles, the Philippines, Mozambique, New Caledonia, and northern Australia off Townsville, Ashmore Reef, and North West Cape. This species inhabits the continental slope at depths of , and is probably found near the sea floor. Description Reaching a length of , the longhead catshark has a soft, very thin body and a long head comprising one-quarter of its total length. The flattened, bell-shaped snout measures roughly 12% of the total length and narrows considerably in front of the nostrils. The oblique nostrils are divided into large, oval incurrent and excurrent openings by triangular flaps of skin on their anterior rims. The small, horizontally oval eyes are somewhat upward-facing, and equipped with rudimentary nictitating membranes. Behind each eye is a modest spiracle. The mouth forms a short, wide arch, with well-developed furrows around the corners. The teeth number 36–44 rows in the upper jaw and over 45 rows in either jaw; each tooth is well-spaced from the next and has three or five cusps, with the central cusp much