Pitted stingray

The pitted stingray (Dasyatis matsubarai) is a type of stingray found only in the waters around Japan and the Sea of Japan. It lives near the coast, usually at depths between 40 and 60 meters, but has also been recorded in the open sea. Its pectoral fin disc is diamond-shaped and can reach 2 meters across, with a total length (including the tail) recorded at 2.8 meters. A key feature is a W-shaped groove on the underside of the disc, a trait it shares only with the groovebelly stingray. Adults have a dark gray back with small white spots and bony tubercles. This species is caught as bycatch by Japanese coastal fisheries and sold for food. The IUCN lists it as Data Deficient due to insufficient information. It is now considered a population of the short-tail stingray (Bathytoshia brevicaudata). The species was first described in 1939 by Japanese ichthyologist Yasunori Miyosi, based on a specimen from the Hyuga-nada Sea in Miyazaki Prefecture. Nishida and Nakaya (1990) regarded the multispine giant stingray (D. multispinosa) as the same as this species, which was confirmed by the study of Last et al. (2016). The pitted stingray lives on the continental shelf around Japan, especially near Hokkaidō and northern Honshū, and has also been recorded near South Korea and Vladivostok, Russia. It is generally a bottom-dweller in coastal waters 40–60 meters deep, but one individual caught near the surface over water 3,000 meters deep suggests it may sometimes swim in open water. The disc is wider than long, with straight leading edges meeting the snout at a blunt angle and rounded trailing edges. The mouth may have zero to 12 papillae arranged in three rows. There are 34–44 upper tooth rows and 33–46 lower tooth rows. The tail is whip-like, 75–122% as long as the disc width, and bears 1–3 stinging spines. The spine averages 6.5 cm in males and 7.7 cm in females, with about 90 and 87 serrations, respectively. Behind the spine is a low dorsal keel and a ventral fin fold less than half the disc width. Mature individuals have 2–10 tubercles on the snout, 3–5 on the back, and 1–8 before the spine. The tail tip is covered in dermal denticles. The upper body is dark gray, the tail fold darker, and the underside white with gray spots and fin margins. The disc has many small pores ringed in white.