Bennett's stingray

Bennett's stingray
Conservation status
Data Deficient (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Myliobatiformes
Family:	Dasyatidae
Genus:	Dasyatis
Species:	D. bennetti
Binomial name
Dasyatis bennetti (J. P. Müller & Henle, 1841)
Synonyms
Trygon bennettii J. P. Müller & Henle, 1841

The Bennett's stingray or frilltailed stingray (Dasyatis bennetti, often misspelled benetti or bennettii)^[2] is a little-known species of stingray in the family Dasyatidae, with a wide but ill-defined distribution in the Indian and Pacific Oceans. This species is characterized by a rhomboid, yellow-brown pectoral fin disc with a fairly long snout, and an extremely long tail with a correspondingly long ventral fin fold. It measures up to 50 cm (20 in) across. It feeds on fish, and is aplacental viviparous. It is likely caught by demersal fisheries, but the International Union for Conservation of Nature (IUCN) does not yet have sufficient information to assess its conservation status.

Taxonomy

German biologists Johannes Peter Müller and Friedrich Gustav Jakob Henle described the Bennett's stingray as Trygon bennettii in their 1839–1841 Systematische Beschreibung der Plagiostomen. They referenced three specimens as the species syntypes: only the one from China remains, while another from Trinidad and a third of unknown provenance have been lost. Later authors synonymized the genus Trygon with Dasyatis.^[3]

Distribution and habitat

The range of the Bennett's stingray is somewhat uncertain due to confusion with other species. It is a bottom-dweller that occurs in the coastal waters of the Indo-Pacific region, from India, through Indochina, to southern China, Japan, and perhaps the Philippines; it seems to be most common in the northwestern Pacific. This species has also been reported from Vanuatu and New Caledonia; the single historical record from Trinidad may be a misidentification.^[1][2] It has been known to enter fresh water, including the Perak River in peninsular Malaysia and the Indragiri River in Sumatra.^[4]

Description

The Bennett's stingray has a diamond-shaped pectoral fin disc almost as wide as long, with straight leading margins converging on a triangular, moderately protruding snout. The trailing margins of the disc are convex. There are 31 upper and 33 lower tooth rows, and 3 or 5 papillae across the floor of the mouth. The tail is whip-like and can measure three times the length of the disc, proportionately longer than any other North Pacific Dasyatis species.^[5] There is a stinging spine on the upper surface of the tail, and a fin fold underneath measuring 60–67% the disc width. Young individuals have small dermal denticles in the middle of the back, whereas adults have a row of tubercles along the midline of the back and tiny thorns covering the tail. The coloration is yellowish brown above, becoming darker on the tail fold, and light below.^[5] This species attains a disc width of 50 cm (20 in) and a total length of 1.3 m (4.3 ft).^[1]

Biology and ecology

There is little information on the natural history of the Bennett's stingray.^[1] It preys on fish, and is aplacental viviparous like other stingrays.^[2]

Human interactions

The Bennett's stingray is susceptible to bottom trawl and net gear and probably caught by fisheries within its range, which include intensive, targeted ray fisheries off Thailand, Singapore, India, and elsewhere. However, no specific data are available and the International Union for Conservation of Nature (IUCN) has listed this species under Data Deficient.^[1]

References

1. ^ ^{a b c d e} Valenti, S.V., SSG Asia Northwest Pacific Red List Workshop (2007). Dasyatis bennetti. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on February 19, 2010.
2. ^ ^{a b c} Froese, Rainer, and Daniel Pauly, eds. (2010). "Dasyatis bennetti" in FishBase. February 2010 version.
3. ^ Eschmeyer, W.N. and R. Fricke, eds. bennetti, Trygon. Catalog of Fishes electronic version (January 15, 2010). Retrieved on February 19, 2010.
4. ^ Taniuchi, T. (1979). "Freshwater Elasmobranchs from Lake Naujan, Perak River, and Indragiri River, Southeast Asia". Japanese Journal of Ichthyology 25 (4): 273–277
5. ^ ^{a b} Nishida, K. and K. Nakaya (1990). "Taxonomy of the genus Dasyatis (Elasmobranchii, Dasyatididae) from the North Pacific". in Pratt, H.L., S.H. Gruber and T. Taniuchi, eds. Elasmobranchs as living resources: advances in the biology, ecology, systematics, and behaviour, and the status of fisheries. NOAA Technical Report, NMFS 90. pp. 327–346.