Dasyatis geijskesi (lat.) Is a little-studied species of the genus of stingrays from the family of the caudate - tailed order of the caudate-like over- order of the rays . They live in the tropical waters of the southwestern and central western parts of the Atlantic Ocean. They are found at a depth of 25 m. The maximum recorded width of the disk is 1.5 m. The pectoral fins of these slopes fuse with the head, forming a diamond-shaped disk, the width of which is equal to the length. The snout is elongated and pointed. The tail is longer than the disk. Upper and lower keels are ventrally located behind the spine on the caudal stem. The dorsal surface of the disc is brown. Like other caudate-like Dasyatis geijskesi, they reproduce by egg-production . Embryos develop in the womb, feeding on the yolk and histotroph . Not subject to target fishing. By- catch can be found in bottom trawling [1] [2] .
| Dasyatis geijskesi |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
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| International scientific name |
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Dasyatis geijskesi Boeseman , 1948 |
| Security status |
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Close to vulnerableIUCN 3.1 Near Threatened : 60153 |
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Content
For the first time, Dasyatis geijskesi was scientifically described by the Danish ichthyologist Martinus Boseiman in 1948 [3] . The basis for the description was an immature male with a 36 cm wide disc, caught off the coast of Suriname . The view is named after the director of the Surinamese Museum in Paramaribo , which supplied the author with material for studying the marine fauna of Suriname [4] .
In 2001, a phylogenetic analysis of 14 species of stingrays based on morphology was published. In it, Dasyatis geijskesi and Dasyatis guttata were recognized as closely related species, forming a treasure with a sharp-tailed stalk , Dasyatis margaritella , Himantura gerrardi and a smooth butterfly slope , as root species . These data reinforce the view that neither the genus of stingrays nor the genus of stingrays-hematures is monophyletic [5] .
Dasyatis geijskesi live in the southwestern and centralwestern parts of the Atlantic Ocean off the northern coast of South America. They are found in coastal brackish waters from Venezuela and Trinidad and Tobago to northern Brazil. They enter the estuaries of the rivers of the Amazon basin . This is one of the rarest species of stingrays in its range [2] . They prefer places with a muddy bottom and poor visibility with a depth of 5-25 m [6] [7] . Dasyatis geijskesi make seasonal migrations caused by changes in salinity, entering dry coastal bays and sailing into the open sea during the rainy season [2] .
The pectoral fins of these slopes fuse together with the head, forming a diamond-shaped disk, the width of which is equal to the length, with a curved front edge and rounded fins (“wings”). Snout elongated and pointed in the form of a triangle. Its length is 39–54% of the width of the disk. Behind the tiny eyes are splashers that exceed them in size. On the ventral surface of the disc are 5 gill slits, mouth and nostrils. Between the nostrils lies a flap of skin with a fringed lower edge. The central part of the mouth is slightly jagged. The teeth are staggered and form a flat surface. On both jaws there are 56–68 dentitions. At the bottom of the oral cavity lies a series of 5 outgrowths [8] [9] .
The length of the ventral fins is 2 times the width. The whip-shaped tail is 2 times longer than the disk. Like other stingrays, on the dorsal surface at the base of the caudal stem there is a serrated spike connected by ducts to the poisonous gland. Sometimes stingrays have 2 spikes. Periodically, the spike breaks off and a new one grows in their place. Behind the spine on the caudal peduncle is the dorsal and ventral skin folds. A series of small bone plaques run along the spine from the eyes to the base of the tail. Large plaques cover the base of the pectoral fins. Behind the poisonous spike, the tail to the tip is covered with conical spines. The dorsal surface of the disc is even brown. The ventral surface of the disk is white, the edges are darker than the main background [8] . The maximum recorded disk width is 1.5 m, although the average size does not exceed 70 cm [1] .
Like other caudate-shaped Dasyatis geijskesi belongs to ovoviviparous fish. Embryos develop in the womb, feeding on the yolk and histotroph. Females bring offspring annually, sailing into coastal waters. There are 1-3 newborns in the litter, whose tail is 3 times longer than the disk. The diet consists of crustaceans, polychaetes and mollusks. Stingrays dig their prey from the ground and crush their shells with their powerful teeth [7] .
Dasyatis geijskesi are targeted by local fishermen. Caught in by-catch in commercial fishing in the Amazon estuary. The meat is eaten. It is painted in dark red color, so it is valued low. The International Union for Conservation of Nature has assigned this species a conservation status of “Close to Vulnerability” [2] .
- ↑ 1 2 Dasyatis geijskesi (English) in the FishBase database.
- ↑ 1 2 3 4 Dasyatis geijskesi (English) . The IUCN Red List of Threatened Species .
- ↑ Boeseman, M. Some preliminary notes on Surinam sting rays, including the description of a new species // Zoologische Mededelingen. - 1948. - Vol. 30, No. (2) . - P. 31-47.
- ↑ Christopher Scharpf and Kenneth J. Lazara. Fish Name Etymology Database (Neopr.) . The ETYFish Project . Date of treatment January 18, 2015.
- ↑ Rosenberger, LJ; Schaefer, SA Phylogenetic Relationships within the Stingray Genus Dasyatis (Chondrichthyes: Dasyatidae) // Copeia. - American Society of Ichthyologists and Herpetologists, 2001. - No. 3 . - P. 615-627. - DOI : 10.1643 / 0045-8511 (2001) 001 [0615: PRWTSG] 2.0.CO; 2 .
- ↑ Cervigón, F., R. Cipriani, W. Fischer, L. Garibaldi, M. Hendrick, AJ Lemus, R. Márquez, JM Poutiers, G. Robaina and B. Rodriquez. Guía de Campo de las Especies Comerciales Marinas y de Aguas Salobres de la Costa Septentrional de Sur America. - Food and Agricultural Organization of the United Nations, 1992. - P. 199. - ISBN 92-5-303129-8 .
- ↑ 1 2 Léopold, M. Poissons de mer de Guyane .. - Editions Quae. - 2004. - P. 41. - ISBN 2-84433-135-1 ..
- ↑ 1 2 Bigelow, HB and WC Schroeder. 2 // Fishes of the Western North Atlantic. - Sears Foundation for Marine Research: Yale University, 1953. - P. 363-364.
- ↑ Santos, H. and P. Charvet-Almeida. Description of females of the stingray Dasyatis colarensis Santos, Gomes & Charvet-Almeida, 2004 (Chondrichthyes: Myliobatiformes: Dasyatidae) // Arquivos do Museu Nacional, Rio de Janeiro. - 2007. - Vol. 65, No. (1) . - P. 19-25.
