Marbled whipray

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Marbled whipray
Stingray shedd.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Myliobatiformes
Family: Dasyatidae
Genus: Fluvitrygon
Species:
F. oxyrhyncha
Binomial name
Fluvitrygon oxyrhyncha
(Sauvage, 1878)
Himantura oxyrhyncha rangemap.png
Range of the marbled whipray
Synonyms
  • Dasybatus krempfi Chabanaud, 1923
  • Trygon oxyrhynchusSauvage, 1878

The marbled whipray (Fluvitrygon oxyrhyncha) is a little-known species of stingray in the family Dasyatidae, native to several freshwater rivers in Southeast Asia. This species has an oval pectoral fin disc with an elongated, pointed snout and a very long, whip-like tail without fin folds. It is characterized by numerous heart-shaped dermal denticles and tubercles on its upper surface, as well as a reticulated pattern of brown blotches on a light background. The maximum recorded disc width is 36 cm (14 in). The marbled whipray has been assessed as Endangered by the International Union for Conservation of Nature (IUCN); it is heavily threatened by fishing and habitat loss, degradation, and fragmentation.

Contents

Taxonomy

French zoologist Henri-Emilé Sauvage originally described the marbled whipray as Trygon oxyrhynchus based on a female specimen caught near Saigon, Vietnam, in an 1878 volume of the scientific journal Bulletin de la Société philomathique de Paris. In 1913, Samuel Garman synonymized this species with Himantura uarnak , a judgment that remained unquestioned in subsequent literature until Maurice Kottelat referenced the name in his 1984 review of Indochinese fishes. [2] This species may also be referred to as the longnose marbled whipray or the marbled freshwater stingray. [3]

Distribution and habitat

Among the few members of its family restricted to fresh water, the marbled whipray has been reported from Saigon in Vietnam, the Mekong River near Tonle Sap and Phnom Penh in Cambodia, the lower Nan and Chao Phraya Rivers in Thailand, and the Mahakam River in Kalimantan, Indonesia. The subpopulations inhabiting these rivers are likely isolated from one another. [1] [2] This bottom-dwelling species favors a sandy substrate in which it can bury itself. [4]

Description

The marbled stingray has a thin, oval-shaped pectoral fin disc longer than wide. The snout is long and triangular, with the pointed tip projecting from the disc. The eyes are small, and immediately followed by spiracles over twice their diameter. There is a curtain of skin between the nares with a fringed trailing margin. The mouth is gently arched and contains an anterior row of four and posterior row of two papillae across the floor, which are followed by a seventh papilla in larger individuals. There are 4042 tooth rows in the upper jaw and 4246 tooth rows in the lower jaw; the teeth are arranged with a quincunx pattern into pavement-like surfaces. The tail measures three times as long as the disc and bears two long stinging spines on top; after the spine the tail becomes thin and whip-like, without any fin folds. [2] [5]

There are numerous flattened, heart-shaped dermal denticles on the back, arranged in a dense central band reaching the base of the tail, and becoming smaller and sparser on the outer portions of the disc. Larger, heart-shaped denticles are scattered over the disc, especially around the "shoulders" and the middle of the back. Two pearl spines are present. There is a line of 4041 flat tubercles running down the dorsal midline, from between the eyes to the tail spines; adult individuals also have two lines of spiny denticles running along the sides of the tail from the spine to the tip. The dorsal coloration is white to light gray, with brownish hexagonal blotches forming a reticulated pattern that fades towards the disc margin. Smaller individuals are covered by many irregular dark spots. The underside is entirely light-colored. [2] This ray attains a disc width of 36 cm (14 in). [3]

Biology and ecology

The natural history of the marbled whipray is poorly understood. It likely feeds on benthic organisms such as small crustaceans and molluscs. Reproduction is aplacental viviparous with females supplying their unborn young with histotroph ("uterine milk"), as in other stingrays. [4] [6]

Human interactions

Only five specimens of the marbled whipray have been deposited in museums. However, it is reportedly locally common in some rivers and streams. It is an infrequent incidental catch of intense fishery activities taking place across much of its range, using demersal tangle nets, fish traps, and hook-and-line. These attractively colored rays, especially the young, are valued by the aquarium trade. Another major threat to the marbled whipray is habitat loss and degradation, from pollution, logging, and dam construction. In Thailand, dams on the Chao Phraya have prevented stingrays in different stretches of the river from intermingling, with a negative effect on genetic diversity. Citing these threats, the International Union for Conservation of Nature (IUCN) has assessed this species as Endangered. During the 1990s, the Thai government initiated a captive breeding program for this and other endangered freshwater stingrays at Chai Nat, but by 1996 the program had been placed on hold. [1] [6]

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<span class="mw-page-title-main">White-edge freshwater whipray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Jenkins' whipray</span> Species of cartilaginous fish

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<span class="mw-page-title-main">Pearl stingray</span> Species of cartilaginous fish

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The tubemouth whipray is a little-known species of stingray in the family Dasyatidae, named for its distinctive, highly protrusible jaws. It is found in shallow, brackish water near mangrove forests and large river mouths along the coasts of southwestern Borneo and southern Sumatra. Measuring up to 1 m (3.3 ft) across, this species has a diamond-shaped pectoral fin disc with an elongated, pointed snout and broadly rounded outer corners. The upper surface of the disc is a plain grayish or brownish in color, and covered by small, flattened dermal denticles. The tubemouth whipray is relatively common at present, but is heavily pressured by habitat degradation and coastal fisheries. The International Union for Conservation of Nature (IUCN) has listed it as Vulnerable.

The Hortle's whipray is a little-known species of stingray in the family Dasyatidae, occurring in shallow estuaries and mud flats off southern New Guinea. This species, growing to 71 cm (28 in) across, has a heart-shaped pectoral fin disc with a long, pointed snout and minute eyes. It has a wide dorsal band of dermal denticles extending from in front of the eyes to the tail, as well as scattered sharp denticles on the snout. The underside of the disc is a distinctive bright yellow in color, sometimes with darker markings around the nostrils, mouth, and gill slits. The Hortle's whipray is threatened by extensive seine fisheries and habitat degradation, leading the International Union for Conservation of Nature (IUCN) to assess it as Near Threatened.

<span class="mw-page-title-main">Black-spotted whipray</span> Species of stingray in the family Dasyatidae

The black-spotted whipray is a species of stingray in the family Dasyatidae, found in coastal waters off southern New Guinea and northern Australia. Long thought to be a variant of the related brown whipray, this species has an angular, diamond-shaped pectoral fin disc and a whip-like tail without fin folds. It is characterized by its dorsal color pattern, which consists of a variably extensive covering of small, close-set dark, and sometimes also white, spots on a grayish brown background. In addition, the tail has alternating light and dark saddles past the stinging spine. This species reaches a maximum recorded width of 80 cm (31 in).

<span class="mw-page-title-main">Brown whipray</span> Species of cartilaginous fish

The brown whipray is a species of stingray in the family Dasyatidae, common in inshore, muddy habitats along the northern coast of Australia. It has often been confused in literature for the honeycomb stingray and the black-spotted whipray, which until recently was thought to be the same species. This species has an angular, diamond-shaped pectoral fin disc and a long, very thin tail without fin folds. It is plain brown above, sometimes with white dots or flecks near the edge of the disc, and white below; the tail is dark all over, with alternating dark and light bands near the tip. The maximum recorded disc width is 74 cm (29 in).

<span class="mw-page-title-main">Blackedge whipray</span> Species of cartilaginous fish

The blackedge whipray is a little-known species of stingray in the family Dasyatidae, found in the coastal waters of the Bay of Bengal and the Gulf of Mannar. Attaining a disc width of 1.8 m (5.9 ft), this species has a diamond-shaped disc with two small concavities on either side of the snout tip, and a long, whip-like tail without tail folds. It is characterized by large thorns with star-shaped bases scattered over the disc, and by the wide, black marginal bands on the underside of the disc. The International Union for Conservation of Nature (IUCN) currently lacks sufficient data to assess the blackedge whipray beyond Data Deficient.

<span class="mw-page-title-main">Leopard whipray</span> Species of cartilaginous fish

The leopard whipray is a little-known species of stingray in the family Dasyatidae, found in the Indian and Pacific Oceans from the Andaman Sea to the Coral Triangle. It is found close to shore at depths shallower than 70 m (230 ft), over soft substrates. Attaining a width of 1.8 m (5.9 ft), this species has a diamond-shaped pectoral fin disc with a pointed snout and an extremely long, whip-like tail without fin folds. Adult rays have a leopard-like dorsal pattern of dark brown rings on a yellowish brown background, as well as a row of enlarged, heart-shaped dermal denticles along the midline of the disc. Newborns and small juveniles have large, solid dark spots and few denticles. The leopard whipray is caught by fisheries in many parts of its range, primarily for meat.

<span class="mw-page-title-main">Honeycomb whipray</span> Species of cartilaginous fish

The honeycomb whipray is a species of stingray in the family Dasyatidae, found widely in the shallow coastal waters of the Indo-Pacific from India to the Malay Archipelago. This large species grows to 1.3 m (4.3 ft) across and has a diamond-shaped disc with rounded corners and a projecting, pointed snout. Its tail is long and whip-like, without fin folds. Adults have a striking dorsal color pattern consisting of large, dark brown rings and reticulations delineated by thin yellow lines, while juveniles have a pattern of large dark spots. This ray can also be distinguished from its similar relatives by an enlarged, pearl-like dermal denticle at the center of the back, which is followed by a few thorns. The International Union for Conservation of Nature (IUCN) has assessed the honeycomb whipray as endangered, as it faces heavy fishing pressure and habitat degradation across much of its range.

<i>Fluvitrygon</i> Genus of cartilaginous fishes

Fluvitrygon is a genus of stingrays in the family Dasyatidae from freshwater in southeast Asia. Its species were formerly contained within the genus Himantura.

References

  1. 1 2 3 Compagno, L.J.V. (2016). "Fluvitrygon oxyrhyncha". IUCN Red List of Threatened Species . 2016: e.T44185A104180982. doi: 10.2305/IUCN.UK.2016-3.RLTS.T44185A104180982.en .
  2. 1 2 3 4 Deynat, P.P. & Y. Fermon (2001). "Resurrection of Himantura oxyrhyncha (Sauvage, 1878) from the synonymy of H. uarnak, a senior synonym of H. krempfi (Chabanaud, 1923) (Myliobatiformes: Dasyatidae)" (PDF). Cybium. 25 (2): 161–176.
  3. 1 2 Froese, Rainer; Pauly, Daniel (eds.) (2010). "Himantura oxyrhyncha" in FishBase . January 2010 version.
  4. 1 2 Baensch, H.A. & R. Riehl. Aquarium Atlas (Volume 4). Steven Simpson Books. pp. 14–15. ISBN   3-88244-058-9.
  5. Fowler, S.L.; R.D. Cavanagh; M. Camhi; G.H. Burgess; G.M. Cailliet; S.V. Fordham; C.A. Simpfendorfer; J.A. Musick (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 350–351. ISBN   2-8317-0700-5.
  6. 1 2 Last, P.R.; W.T. White; J.N. Caire; Dharmadi, Fahmi; K. Jensen; A.P.F. Lim; B. Mabel-Matsumoto; G.J.P. Naylor; J.J. Pogonoski; J.D. Stevens & G.K. Yearsley (2010). Sharks and Rays of Borneo. CSIRO Publishing. pp. 204–205. ISBN   978-1-921605-59-8.