Bathyraja caeluronigricans is a species of cartilaginous fish of the genus of deepwater stingrays of the Arhynchobatidae family of the stingrays . They live in the temperate waters of the northern part of the Pacific Ocean . They are found at a depth of up to 400 m. Their large, flattened pectoral fins form a rounded disk with a triangular snout. Lay eggs. The maximum width of the disc is 74.4 cm. They are not the target fishing target [1] [2] [3] .
| Bathyraja caeluronigricans |
| Scientific classification |
|---|
| No rank : | Bilateral symmetrical |
| Family: | One-Feathered Rays |
| View: | Bathyraja caeluronigricans |
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| International scientific name |
|---|
Bathyraja caeluronigricans Ishiyama & Ishihara , 1977 |
| Security status |
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Not enough data IUCN Data Deficient : 161424 |
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The species was first scientifically described in 1977. Species epithet comes from the word lat. caeluronigrocans is “purple-black” and is due to the color of the dorsal surface of the disk [4] . The holotype is an adult male with a disk width of 74.4 cm, caught off the coast of Hatinohe ( ), Japan , at a depth of 200-400 m. Paratypes are immature females with a disc 37.7-60 cm wide, immature males with a 44.5-67.7 cm wide disc, adult females with a 67.4-72.2 cm wide disc and adult males with a 69.6 wide disc –72.8 cm caught there [5] . In some sources, the species Bathyraja caeluronigricans and Bathyraja matsubarai are indicated as synonyms [2] .
These stingrays live in the northwestern part of the Pacific Ocean off the coast of Japan and Russia ( Kuril Islands ). Their presence in the Bering Sea , near the Aleutian Islands and in the western part of Alaska Bay has not been confirmed [2] . They are found at a depth of 200-400 m [3] . According to other data, they are kept on the outer edge of the continental shelf and in the upper part of the continental slope on a sandy-pebble, sandy or silty-pebble bottom at a depth of 120-2000 m, the most common in the depth range of 550-1300 m. The temperature in the environment varies within 0–5.5 ° C (average value of 2.82 ° C), most often these slopes come across at a temperature of 2.5–3.5 ° C [2] .
The broad and flat pectoral fins of Bathyraja caeluronigricans form a rhombic disk with a wide triangular snout and rounded edges. The snout is short, soft and wide. Behind the eyes there are splashes that exceed them in length. The space between them is flat and vast. On the ventral side of the disc are 5 gill slits, nostrils and mouth. The tail is longer than the disk. On the tail there are lateral folds located on the back half. 2 dorsal fins of the same size are located at a close distance from each other. The caudal fin has been reduced [1] [4] . The dorsal surface of the disc is rough, covered with large spines and spines. A number of spines lie along the spine from the scalp arch to the first dorsal fin. The disc is painted dark purple-brown, the ventral surface is light and smooth. The areas in front of the mouth, behind the gill slits, around the cloaca and sensory pores are whitish. The rostral cartilage is short and soft. Males have long cylindrical pterygopodia with a rounded end. The total number of vertebrae is 119–124 [4] . The maximum recorded length is 126 cm [2] , and the disk width is 74.4 cm [3] .
Embryos feed exclusively on yolk . These stingrays lay eggs enclosed in a horn capsule with hard "horns" ending in a fibrous end [1] [2] . The surface of the capsules is rough, covered with longitudinal rows of tiny spikes [4] . The length of the capsules is 8.5–11.3 cm, and the width is 5.2–6.9 cm [2] .
Males and females reach puberty with a length of 82.1-108 cm and 88.6-104.8 cm, aged 6-7 years and 6-8 years, respectively. The diet of large individuals consists mainly of fish and cephalopods , young animals feed on worms and small crabs [2] .
These skates are the target fishing target. At present, the domestic fishing industry practically does not use stingrays; in Japan and in the countries of Southeast Asia they serve as objects of specialized fishing. In general, fishing does not have a significant effect on population size. The data for the assessment of the conservation status of the species by the International Union for Conservation of Nature are insufficient [2] .
