The pitted stingray (''Bathytoshia matsubarai'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae ( ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Dasyatidae,

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the waters around

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

and the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...

. It typically found near the coast at depths of , but may also venture into the

open sea The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

. Measuring up to across, the pitted stingray has a diamond-shaped

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

disc with a characteristic "W"-shaped groove on the underside. The total length including the tail has a record of . Other identifying characteristics of this species include its dark gray dorsal coloration with small white spots, and the presence of dorsal

tubercles In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection ...

in adults. Pitted stingrays are caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

in coastal

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

and brought to market. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) does not yet have sufficient data to assess this species beyond

Data Deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

. Some authors regard this species as the same as the

Short-tail stingray The short-tail stingray or smooth stingray (''Bathytoshia brevicaudata'') is a common species of stingray in the family Dasyatidae. It occurs off southern Africa, typically offshore at a depth of , and off southern Australia and New Zealand, fro ...

Taxonomy

Japanese

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Yasunori Miyosi described the pitted stingray in a 1939 issue of the ''Bulletin of the Biogeographical Society of Japan'', based on a specimen collected from the Hyuga-nada Sea in eastern

Miyazaki Prefecture is a prefecture of Japan located on the island of Kyūshū. Miyazaki Prefecture has a population of 1,073,054 (1 June 2019) and has a geographic area of 7,735 km2 (2,986 sq mi). Miyazaki Prefecture borders Ōita Prefecture to the north, Kuma ...

, Japan.Catalog of Fishes (Online Version)
California Academy of Sciences. Retrieved on January 9, 2010. Nishida and Nakaya (1990) regarded the multispine giant stingray (''B. multispinosa'') as the same as this species, which was confirmed by the study of Last et al. (2016).

Distribution and habitat

The pitted stingray is found over the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

around Japan, and is particularly abundant around

Hokkaidō is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The la ...

and northern

Honshū , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separa ...

.Nishida, K. and K. Nakaya (1990). "Taxonomy of the genus ''Dasyatis'' (Elasmobranchii, Dasyatididae) from the North Pacific." in Pratt, H.L., S.H. Gruber and T. Taniuchi. ''Elasmobranchs as living resources: advances in the biology, ecology, systematics, and behaviour, and the status of fisheries.'' NOAA Technical Report, NMFS 90. pp. 327–346. It has also been recorded from elsewhere in the Sea of Japan, near

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

and

Vladivostok Vladivostok ( rus, Владивосто́к, a=Владивосток.ogg, p=vɫədʲɪvɐˈstok) is the largest city and the administrative center of Primorsky Krai, Russia. The city is located around the Zolotoy Rog, Golden Horn Bay on the Sea ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. The pitted stingray is generally a bottom-dweller inhabiting coastal waters deep. However, the capture of one individual near the surface over water deep in the Sea of Japan suggests that this species may have

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

habits as well.

Description

The pitted stingray has a diamond-shaped

disc wider than long, with almost straight leading margins converging to the tip of the snout at a blunt angle, and rounded trailing margins. The floor of the mouth contains anywhere from zero

papilla Papilla (Latin, 'nipple') or papillae may refer to: In animals * Papilla (fish anatomy), in the mouth of fish * Basilar papilla, a sensory organ of lizards, amphibians and fish * Dental papilla, in a developing tooth * Dermal papillae, part of ...

e to 12, arranged in three rows of 3, 7 and 2. There are 34–44 upper tooth rows and 33–46 lower tooth rows. There is a distinctive "W"-shaped furrow on the underside of the disc, at the center behind the fifth pair of

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s. Only one other member of its family, the

groovebelly stingray The groovebelly stingray (''Dasyatis hypostigma''), referred to as the butter stingray by fishery workers, is a species of stingray in the family Dasyatidae. It is found over sandy or muddy bottoms in shallow coastal waters off southern Brazil, ...

(''D. hypostigma''), shares this feature. The tail is whip-like and measures 75–122% of the disc width, bearing 1–3 stinging spines on the upper surface. The tail spine averages long with 90 serrations in males, and long with 87 serrations in females. Behind the spine, there is a low dorsal keel and a ventral fin fold measuring less than half as long as the disc width. Mature individuals have a row of 2–10 tubercles on the snout tip, 3–5 tubercles on the back, and 1–8 tubercles before the spine. The tail is covered by

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s towards the tip. This species is dark gray above, darkening on the tail fold, and white below with gray irregular spots and fin margins. The upper surface of the disc bears many small pores that are ringed in white. The pitted stingray attains a disc width of . At Shima Marineland, a Japanese public aquarium, there is a record that individuals bred for 28 years have reached a disc width of and a total length of .

Biology and ecology

Little is known of the natural history of the pitted stingray. This species is parasitized by the praniza

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e of gnathiid

isopod Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

s, which attach to the gills. Reproduction is presumably

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

like other stingrays.

Human interactions

The pitted stingray is caught incidentally by Japanese coastal

, using longlines,

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s, and set nets, and marketed for human consumption. However, the significance of this species in catches relative to other stingray species is unknown. As a result, the

(IUCN) has listed it as

References

{{Taxonbar, from=Q140428 Dasyatis Fish described in 1939 Taxobox binomials not recognized by IUCN