Himantura oxyrhyncha (lat.) Is a poorly studied species of the genus of stingrays -hematures from the family of the caudate - tailed squad of the caudate - shaped overorder of the rays . They live in the tropical waters of some rivers of Southeast Asia . The maximum recorded width of the disk is 36 cm. The pectoral fins of these slopes fuse with the head, forming a rounded disk. The snout is elongated and pointed. The tail is longer than the disk; skin folds on the caudal stem are absent. The disk is studded with numerous heart-shaped scales and plaques, and is also covered with a mottled twisting pattern of dark brown lines on a light background. The species suffers from intense fisheries and environmental degradation.
| Himantura oxyrhyncha |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
| View: | Himantura oxyrhyncha |
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| International scientific name |
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Himantura oxyrhyncha ( Sauvage , 1878) |
| Synonyms |
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- Trygon oxyrhynchus Sauvage, 1878
- Dasybatus krempfi Chabanaud, 1923
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| Area |
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| Security status |
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Endangered speciesIUCN 3.1 Endangered : 44185 |
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Like other tail-like Himantura oxyrhyncha reproduce by egg-production . Embryos develop in the womb, feeding on the yolk and histotroph . The diet of these stingrays consists mainly of crustaceans and mollusks [1] [2] .
Content
For the first time, a new species was described by the French zoologist Henri Emil Sovage as Trygon oxyrhyncha in 1878 [3] . Species epithet comes from the words of the other Greek. οξύς - "sharp" and Greek. ῥινός - “nose” [4] . In 1913, Samuel Garman recognized him as a synonym for Himantura uarnak and this assessment was not in doubt until 1984, when the original name was restored [5] .
Himantura oxyrhyncha are endemic to the freshwater rivers of Vietnam , Cambodia , Thailand and Indonesia . They live in the Tonle Sap , Nan , Chauphray and Mahakam rivers . The subpopulations that inhabit these rivers are isolated from each other [2] [5] . These bottom fish prefer sandy soil, which is able to completely burrow [6] .
The pectoral fins of these slopes fuse with the head, forming an oval disk, the length slightly exceeds the width. The narrow triangular snout is elongated, its tip protrudes beyond the edge of the disk. Behind the small eyes are large spatter . On the ventral surface of the disk are 5 pairs of S-shaped gill slits, mouth and nostrils. Between the nostrils lies a flap of skin with a fringed lower edge. The mouth is curved in the form of an arc, at the bottom of the oral cavity there are 2 rows of processes arranged in 4 and 2. Large individuals have a third row of 7 processes. Small blunted teeth are staggered and form a flat surface. In the mouth there are 40–42 upper and 42–46 lower dentitions. The thin whip-shaped tail is 3 times the length of the disc. There are no skin folds on the caudal peduncle. On the dorsal surface of the caudal peduncle there are 2 thin spines [5] [7] .
The dorsal surface of the disc is densely covered with tiny heart-shaped scales, which are located in a wide strip from the area between the eyes to the tail. Small sharp scales are scattered along the snout and concentrated on its tip. Behind the spike, the caudal stem is evenly covered with scales. The lateral line is well developed on the dorsal and ventral sides of the disk. Color of the dorsal surface of the disc of small rays of greenish-gray in color, large individuals yellow-brown. The caudal peduncle is even brown, the area in front of the spine is lighter. The ventral surface of the disk is bright yellow with a thin dark fringing at the edges and dark marks around the nostrils, mouth and gill slits [3] . The maximum recorded disk width is 75 cm [1] .
The diet of these rays is mainly crustaceans, mollusks and small fish [1] .
Like other caudate-tailed Himantura oxyrhyncha belongs to ovoviviparous fish. Embryos develop in the womb, feeding on the yolk and histotroph. The disk width of newborns is about 20 cm [2] .
Himantura oxyrhyncha are not subject to target fishing. These stingrays are caught by- catch in the commercial shrimp fishery. The species suffers from environmental degradation due to anthropogenic factors. From 1980 to 2005, the area of mangroves decreased from 545,000 to 380,000 hectares (over 30%). The International Union for Conservation of Nature has assigned this species the status of conservation “Vulnerable” [2] .
- ↑ 1 2 3 Himantura oxyrhyncha in the FishBase database.
- ↑ 1 2 3 4 Himantura oxyrhyncha (English) . The IUCN Red List of Threatened Species .
- ↑ 1 2 Sauvage, HE Sur une Himantura de Cochinchine // Bulletin de la Société philomathique de Paris, (7th Série). - 1878. - Vol. 2. - P. 90-91.
- ↑ Great Ancient Greek Dictionary (Neopr.) . Date of treatment March 27, 2015. Archived February 12, 2013.
- ↑ 1 2 3 Deynat, PP and Y. Fermon. Resurrection of Himantura oxyrhyncha (Sauvage, 1878) from the synonymy of H. uarnak, a senior synonym of H. krempfi (Chabanaud, 1923) (Myliobatiformes: Dasyatidae) // Cybium. - 2001. - Vol. 25, No. (2) . - P. 161-176.
- ↑ Baensch, HA and R. Riehl. Aquarium Atlas (Volume 4). {{{title}}}. - Steven Simpson Books. - S. 14-15. - ISBN 3-88244-058-9 .
- ↑ Fowler, SL, Cavanagh, RD, Camhi, M., Burgess, GH, Cailliet, GM, Fordham, SV, Simpfendorfer, CA and Musick, JA Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. - International Union for Conservation of Nature and Natural Resources, 2005. - P. 106–109, 287–288. - ISBN 2-8317-0700-5 .
