Dasyatis margaritella (lat.) Is a species of the genus of stingrays from the family of the caudate - tailed order of the caudatoids over- order of rays . They live in the tropical coastal waters of West Africa . The maximum recorded width of the disk is 30 cm. The pectoral fins of these slopes fuse with the head, forming a rounded disk, the width of which is almost equal to the length. Pointed snout. The tail is longer than the disk. Behind the spike on the caudal stem are the ventral and dorsal skin keels. A wide strip of scales runs along the back. In the center of the disk there is a large, pearl - like pearl spike. This feature is also characteristic of larger Guinean stingrays, with which Dasyatis margaritella is often confused [1] . Coloring of the dorsal surface of the disc of an even gray-brown color. Like other caudate-like Dasyatis margaritella, they reproduce by egg-production . Embryos develop in the womb, feeding on the yolk and histotroph . In litter 1-3 newborns. They are the subject of targeted fishing. By- catch comes from commercial and artisanal fishing [2] [3] .
| Dasyatis margaritella |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
| View: | Dasyatis margaritella |
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| International scientific name |
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Dasyatis margaritella Compagno & TR Roberts , 1984 |
| Security status |
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Not enough data IUCN Data Deficient : 161520 |
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Content
For the first time, a new species was scientifically described in 1984 [1] . Earlier in the scientific literature, Dasyatis margaritella was not separated from Guinean stingrays, although since 1965 it was known that these are two different species. The holotype is a male 19 cm long, caught in the waters of Cameroon . Paratypes are a male 16.9 cm long and a female 18 cm long, caught there [4] . Species epithet comes from the word lat. margaritas - "pearls" [5] . Externally, Dasyatis margaritella is similar to Guinean stingrays and Dasyatis garouaensis , which also live off the coast of West Africa. They are probably closely related species [1] . Until now, the reports on the composition of the catch of these skates have been confused with each other [3] .
In 2001, a phylogenetic analysis of 14 species of stingrays based on morphology was published. In it, Dasyatis margaritella and Himantura gerrardi were recognized as closely related species, forming a treasure with a pointed tail and 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 . Guinean stingrays and Dasyatis garouaensis were not included in the study [6] .
Dasyatis margaritella live on the coast of West Africa from Ras Nouadhibou , Mauritania , to Angola . They are found in coastal sea and brackish waters; they enter river estuaries, including the mouth of the Congo River [3] [7] .
The pectoral fins of these slopes fuse with the head, forming a rounded flat disk, the width is almost equal to the length. The front edge of the disk is curved, the snout is pointed, protrudes beyond the disk. Behind the eyes are sprays of the same 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 mouth is curved in an arc, there are grooves in the corners. At the bottom of the oral cavity there are 5 outgrowths. The teeth are staggered and form a flat surface. There are 24–41 upper and 34–50 lower dentitions in the mouth. The teeth of adult males are longer than those of females and immature males, but are not pointed. Short ventral fins are triangular in shape and protrude slightly from under the disc [1] [7] .
The tail in the form of a whip is longer than the disk. The base of the tail is wide and flattened; towards the end, the tail is highly defined. Like other stingrays, on the dorsal surface in the central part 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 [8] . Behind the thorn on the caudal stem are well developed ventral and low dorsal folds of the skin. In the center of the disk there is a large pearly spine. The skin of young stingrays is devoid of scales. In skates with a disc more than 13-14 cm wide, from the middle third in the eye area to the base of the tail lies a wide strip of flat, rounded scales. The tail stalk behind the spine is covered with spines. The color of the dorsal surface of the disc is even gray. The ventral surface of the disc is white [1] [7] . The maximum recorded disk width is 30 cm and the weight is 1 kg. Dasyatis margaritella differs from externally similar Guinean stingrays in a relatively smaller pearly spike in the center of the disk, a large number of dentitions and less numerous rays of pectoral fins (113–127 against 129–136) [7] .
Like other caudate-like, these rays belong to ovoviviparous fish. Embryos develop in the womb, feeding on the yolk and histotroph. In the litter from 1 to 3 newborns. Puberty occurs at a disc width of about 20 cm [6] .
Despite their small size, Dasyatis margaritella are subject to commercial fishing in the waters of Senegal, Ghana and Côte d'Ivoire . They are caught with the help of longlines, bottom trawls, fixed and gill nets, net, traps and hook. The size of the catch is difficult to estimate due to its similarity to Guinean stingrays. There is insufficient data to evaluate the conservation status of the species by the International Union for Conservation of Nature [3] .
- ↑ 1 2 3 4 5 Compagno, LJV and TR Roberts. Marine and freshwater stingrays (Dasyatidae) of West Africa, with description of a new species. "Proceedings of the California Academy of Sciences (Series 4). - 1984. - Issue 43. - No. (18) . - P. 283— 300 .
- ↑ Dasyatis margaritella (English) in the FishBase database.
- ↑ 1 2 3 4 Dasyatis margaritella (English) . The IUCN Red List of Threatened Species .
- ↑ Dasyatis margaritella (neopr.) . Shark References. Date of treatment February 16, 2015.
- ↑ Large Latin-Russian Dictionary. (unspecified) . Date of treatment February 14, 2015.
- ↑ 1 2 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 .
- ↑ 1 2 3 4 Stiassny, MLJ, GG Teugels and C. Hopkins. Poissons d'eaux douces et saumâtres de basse Guinée, ouest de l'Afrique centrale (Volume 2) .. - IRD Editions, 2008 .-- T. 2 .-- P. 161-163. - ISBN 2-7099-1620-7 .
- ↑ McEachran, JD and MR de Carvalho. Dasyatidae. Stingrays = In KE Carpenter (ed.) FAO species identification guide for fishery purposes. The living marine resources of the Western Central Atlantic. Vol. 1: Introduction, molluscs, crustaceans, hagfishes, sharks, batoid fishes, and chimaeras. - 2003.
