Japanese roughshark

Japanese roughshark
Conservation status
Data Deficient (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Squaliformes
Family:	Oxynotidae
Genus:	Oxynotus
Species:	O. japonicus
Binomial name
Oxynotus japonicus Yano & Murofushi, 1985
Range of the Japanese roughshark

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The Japanese roughshark, Oxynotus japonicus, is a rare species of shark in the family Oxynotidae, known only from a handful of specimens recovered from Suruga Bay and the Enshunada Sea off Japan. It is a benthic species that occurs at a depth of 150–350 meters. This shark is caught (and discarded) as by-catch by bottom trawlers throughout its entire limited range, and may be threatened given the declines in other bottom deep sea species in Suruga Bay.^[1]

This species grows to 64.5 cm long.^[1] It is similar to other rough sharks in having a stout, high trunk, a dorsally depressed head, and two sail-like dorsal fins with deeply embedded spines. The snout is short, with large nostrils whose lateral and medial apertures are separated by a thick nasal flap. The eyes and spiracles are oval in shape. The five pairs of gill slits are very small and vertical. The mouth is small, with thick, fleshy lips; the teeth in the upper jaw are narrow, erect, and smooth-edged, while those in the lower jaw are broad, blade-like, and smooth-edged. Only one row of teeth in the lower jaw are functional.^[2]

The large dorsal fins are subtriangular in shape, with the first dorsal spine sloping slightly backward. The pectoral fins have a convex front margin and a concave rear margin. The anal fin is absent. There is a strong ridge running between the pectoral and pelvic fins on each side of the body. The dermal denticles are large and widely spaced, giving the skin a very rough texture. This species differs from the similar sailfin roughshark in the positioning of the dorsal fins and the shape of the spiracle. The color is a uniform dark brown, with the lips, nasal flap margins, fin axils and inner margins of claspers white.^[2]

Reproduction is ovoviviparous, as in other dogfish sharks.^[3] Size at maturity is 59 cm long for females and 54 cm long for males.^[1]

References

1. ^ ^{a b c d} Yano, K. (2004). Oxynotus japonicus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on December 22, 2008.
2. ^ ^{a b} Yano, K. and Murofushi, M. (1985). "A New Prickly Dogfish, Oxynotus japonicus, from Japan". Japanese Journal of Ichthyology 32 (2): 129–136. 
3. ^ Froese, Rainer, and Daniel Pauly, eds. (2008). "Oxynotus japonicus" in FishBase. December 2008 version.