Plesiobatis daviesi (lat.) Is a species of cartilaginous fish from the order of the caudate-like , the only one in the genus Plesiobatis and the family of plesiobates [1] (Plesiobatidae). These rays are widespread in the Indo-Pacific region. They are found in the upper part of the continental slope to a depth of 680 m. The maximum recorded length is 2.7 m. Their pectoral fins form a rounded disk, the snout is elongated, pointed and flexible. Almost half of the tail is a thin caudal fin in the form of a leaf. Dorsal fins absent. The color of the upper part of the disk is dark, the bottom is white. The skin is covered with scales [2] [3] .
| Plesiobatis daviesi |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
| Family: | Plesiobate ( Plesiobatidae Nishida, 1990 ) |
| Gender: | Plesiobatis Nishida, 1990 |
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| International scientific name |
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Plesiobatis daviesi ( JH Wallace , 1967) |
| Synonyms |
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- Urolophus marmoratus
Chu, Hu & Li, 1981 - Urotrygon daviesi JH Wallace, 1967
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| Area |
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| Security status |
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Least ConcernedIUCN 3.1 Least Concern : 60111 |
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These stingrays reproduce by egg production , the embryos feed on yolk and histotroph . The diet consists of crustaceans , cephalopods and bony fish . Not of interest for commercial fishing. By- catch is sometimes found in deep-sea fishing. Care should be taken when handling skates that are caught, as poisonous spikes are located at the base of their tail [2] [3] .
Content
The new species was first described in 1967 as part of a report from the Oceanographic Research Institute , Durban [4] . The species was named after David H. Davis, the last director of this institute, and assigned to the genus of urotrigons on the basis of their morphology (long thin tail and lack of dorsal fins). The holotype is an adult male 171.7 cm long, 92.2 cm wide, 25.4 kg in weight, caught at the mouth of the Limpopo River at a depth of 430-440 m ( ). Paratype: an immature male 59.6 cm long, caught there [5] .
In 1990, a phylogenetic study was carried out that showed that Plesiobatis daviesi and Hexatrygon bickelli are the most basic members of the suborder Myliobatoidei . Then the species was assigned to the genus Plesiobatis of the independent family Plesiobatidae. The name of the family and clan comes from the words dr. πλησίος - “near” and lat. batis - "ramp" [6] [7] . Further morphological studies confirmed the basal position of the genus Plesiobatis , however, they disproved their kinship with the nearest taxa. A study conducted in 1996 was not able to accurately determine the position of the genus, which was previously assigned to the family of six-ganglion rays [8] . In 2004, it was found that the genus Plesiobatis is a closely related taxon with the genus Urolofs and it is recommended that it be assigned to the family of short-tailed stingrays [9] . Until the position of the genus is completely clarified, the authors prefer to attribute it to their own family Plesiobatidae [10] [1] .
Plesiobatis daviesi live in the Indo-Pacific region off the coast of KwaZulu-Natal , South Africa , Mozambique , in the Gulf of Manara , in the north of the Andaman Islands , in the South China Sea , off the Ryukyu Islands , along the southern coast of Australia , in the northwestern waters of Australia from reefs Rowley to Shark Bay , off the northeast coast of Australia from Townsville to Woolie , off New Caledonia and the Hawaiian Islands [2] [11] [12] [13] . They are found on the mainland slope at depths from 275 to 680 m; they prefer a silty bottom [13] . There is isolated evidence that off the coast of Mozambique these slopes came across at an abnormal depth of 44 m for them. In tropical Asian waters they are quite common, less common in other places [2] .
The body is flabby [13] , the pectoral fins form a rounded disk, the length of which exceeds the width. The front edge of the body forms an obtuse angle. The snout is thin, 6 times longer than the diameter of the eyeball , its tip protrudes slightly beyond the edges of the disk. Behind small eyes, there are sprays with a pointed posterior edge. Large rounded nostrils are located next to the mouth, to which they are connected by a pair of wide grooves. Between the nostrils there is a wide leather flap with a strongly wrinkled edge. A wide straight mouth contains 32-60 dentitions on each jaw. Adults have more teeth. Each tooth ends with a low blunt point; in adult males, the central teeth are sharper and beveled back. Five gill slits on each side on the lower side of the disk [10] [12] .
The ventral fins are small; their outer edges are rounded. The length of the rather thick tail is 93-102% of the length of the disk. Lateral folds of skin on the tail and dorsal fins are absent. On the dorsal surface, one or two serrated spines are located in the middle part of the tail. Behind it begins a long and thin caudal fin in the form of a leaf, the upper and lower lobes of which are almost symmetrical. The skin is densely covered with scales. On the ventral fins, on the ventral surface of the edges of the disc and around the mouth, scales are absent or rarely scattered.
The color of the dorsal surface is from crimson to blackish, some individuals have dark spots and irregular marks. The ventral side is white with a dark stripe at the edges of the disc. The underside of the caudal peduncle and caudal fin are dark. The maximum recorded length is 2.7 m, width 1.5 m, and weight 118 kg. The largest specimen was caught off the coast of South Africa; off the coast of Australia, the length of these slopes does not exceed 2 m [4] [10] [12] .
Black sharks are known to
attack the stingrays of
Plesiobatis daviesi . The diet of Plesiobatis daviesi consists of cephalopods, crustaceans ( shrimps , crabs and lobsters ) and bony fish. The long and flexible snout is well adapted to dig in sediments, while the presence of mesopelagic animals in the diet suggests that these stingrays can hunt not only at the bottom [13] . On one specimen, numerous traces of black shark bites were found, which are able to bite pieces of meat from the body of their victims, exceeding their size [10] .
Plesiobatis daviesi reproduce by live birth, embryos feed on yolk and histotroph. Given the large size and deep-sea habitat, we can conclude that this is a slowly breeding species of skates with a few litters and a long gestation period. The length of the newborns is about 50 cm. There were young stingrays of about that length with the remnants of a scar from the yolk sac. Males and females reach puberty with a length of 1.3-1.7 m and 1.9-2 m, respectively [2] [2] [10] [12] .
Plesiobatis daviesi are not of interest to commercial fishing. Once caught, they furiously hammer their tail and are capable of causing serious injury to the fisherman. Their meat is edible, but not much valued [12] [13] . Underwater fishing is not intensive in their range, so they are caught only in small quantities as by- catch . The International Union for Conservation of Nature has assigned this species a conservation status of “Least Concerns” [2] .
- ↑ 1 2 Nelson D.S. Fishes of World Fauna / Transl. 4th rev. English ed. N. G. Bogutskaya, scientific. Ed. by A. M. Nasek, A. S. Gerd. - M .: LIBROKOM Book House, 2009. - P. 140. - ISBN 978-5-397-00675-0 .
- ↑ 1 2 3 4 5 6 7 Plesiobatis daviesi (English) . The IUCN Red List of Threatened Species .
- ↑ 1 2 Plesiobatis daviesi (English) in the FishBase database.
- ↑ 1 2 Wallace JH (1967). The batoid fishes of the east coast of Southern Africa. Part II: Manta, Eagle, Duckbill, Cownose, Butterfly and Sting Rays. Investigational Report Oceanographic Research Institute, 16: 1-56, 24 fig.
- ↑ Plesiobatis daviesi (neopr.) . Shark References. Date of treatment September 2, 2014.
- ↑ Large Latin-Russian Dictionary. (unspecified) . Date of treatment September 2, 2014.
- ↑ Large Ancient Greek Dictionary (Neopr.) (Inaccessible link) . Date of treatment September 2, 2014. Archived February 12, 2013.
- ↑ McEachran JD, Dunn KA, Miyake T. Interrelationships within the batoid fishes (Chondrichthyes: Batoidea) = In Stiassney MLJ, Parenti LR, Johnson GD, eds. Interrelationships of Fishes. - Academic Press, 1996 .-- S. 63–84. - ISBN 0-12-670951-3 .
- ↑ McEachran JD, Aschliman N. Phylogeny of Batoidea = In Carrier LC, Musick JA, Heithaus MR Biology of Sharks and Their Relatives. - CRC Press, 2004 .-- S. 79-113. - ISBN 0-8493-1514-X .
- ↑ 1 2 3 4 5 Last PR, Stevens JD Sharks and Rays of Australia. - (second ed.). - Harvard University Press, 2009 .-- S. 394-395. - ISBN 0-674-03411-2 .
- ↑ Akhilesh KV, Manjebrayakath H., Ganga U., Pillai NGK, Sebastine M. Morphometric characteristics of deepwater stingray Plesiobatis daviesi (Wallace, 1967) collected from the Andaman Sea // Journal of the Marine Biological Association of India. - 2009. - Vol. 51, No. 2 . - P. 246-249.
- ↑ 1 2 3 4 5 Compagno LJV, Last PR Plesiobatidae. Giant stingaree. - Food and Agricultural Organization of the United Nations, 1999. - Vol. 3 FAO Identification Guide for Fishery Purposes: The Living Marine Resources of the Western Central Pacific. - P. 1467-1468. - ISBN 92-5-104302-7 .
- ↑ 1 2 3 4 5 Last PR, White WT, Caire JN, Dharmadi, Fahmi, Jensen K., Lim APK, Mabel-Matsumoto B., Naylor GJP, Pogonoski JJ, Stevens JD, Yearsley GK Sharks and Rays of Borneo. - CSIRO Publishing, 2010 .-- S. 180-181. - ISBN 978-1-921605-59-8 .
