Himantura kittipong
Encyclopedia
The roughback whipray is a rare species
of freshwater
stingray
in the family
Dasyatidae, found over sandy bottoms in the Mae Klong
and Chao Phraya River
s of Thailand
. Growing no more than 29 cm (11.4 in) across, this small ray has an oval pectoral fin disc and a whip-like tail without fin folds. It closely resembles the white-edge freshwater whipray
(H. signifer) in appearance, but can be distinguished by its coloration: light gray to dark orange-brown above and white below with a dark band along the lateral margins. Another identifying feature is a "pearl organ" (enlarged dermal denticle) at the center of the back, found in individuals of all ages. All of the original specimens of the roughback whipray were found with extensive wounds to the fins and tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Endangered, citing the extensive habitat degradation and heavy fishing pressure within its limited range.
Senior Freshwater Biologist Chavalit Vidthayanon and Smithsonian Research Associate Tyson Roberts in a 2005 issue of the scientific journal
Natural History Bulletin of the Siam Society. They named the ray after Bangkok
aquarium fish dealer and prominent fish expert Khun Jarutanin Kittipong, who the year before had provided the original five specimens that formed the basis for the description. A female 26 cm (10.2 in) across was designated as the type specimen. Based on morphology
, H. kittipongi seems to be most closely related to H. signifer, which shares its range.
, Thailand
, in fresh water
above the influence of the tide
. Additional records of this ray exist from the Chao Phraya River
, and perhaps the Penang River
in Peninsular Malaysia
. The total range of the roughback whipray is estimated to cover less than 5000 square kilometre. This bottom-dwelling species inhabits main river channels at a depth of 5–20 m (16.4–65.6 ft). In contrast to H. signifer, which favors muddy bottoms, it appears to favor sandy to silty substrates.
s. There is a curtain of skin between the nostrils with a gently concave or lobed posterior margin. There are 4–5 papillae (nipple-like structures) across the floor of the small mouth. The small teeth are arranged in 4–5 series in the upper jaw and 14–15 series in the lower jaw; in some individuals, the outermost teeth are stained orange-brown. The whip-like tail lacks fin folds and bears one or two serrated, stinging spines on the upper surface, which are seldom found intact.
The dermal denticles are better-developed than those of H. signifer, with a central band of denticles covering the dorsal surface of the disc and tail base. There is also an enlarged "pearl organ" in the middle of the back that is present throughout life, and a row of enlarged denticles (some thorn-like) running from the pearl to the base of the sting. The disc is light gray or brown to dark orange-brown above, with a white to yellow spot just before the eyes and behind the spiracles, and sometimes a subtle, lighter band running around the margin. The underside of the disc is white, and unlike in H. signifer there is a dark (but not black) marginal band that extends from about one-third of the disc length back from the snout top, to the pelvic fins. The tail is gray to orange-brown above and white below at the base, becoming white with dark spots or nearly black past the sting. A small species, the largest known specimen is a female 29 cm (11.4 in) across.
, which are usually found with their tails intact. Kittipong has proposed that these wounds are inflicted by pufferfish
es (Monotrete cf. leiurus and M. cf. nigroviridis); though plausible, why these wounds are seldom found on H. signifer remains a mystery. Another possibility is that the truncation of the tail is self-inflicted, which would be consistent with the similar lengths of the tail remnant in all five specimens. With a particularly small mouth, this species likely feeds on small crustacean
s and other benthic invertebrate
s. Like other stingrays, it is aplacental viviparous with females provisioning their developing embryo
s with histotroph ("uterine milk"). Males reach sexual maturity
at around 25 cm (9.8 in) across.
in demersal tangle nets
, fish trap
s, and on hook-and-line. It may be sold as food like other freshwater stingrays in the region, or to the aquarium trade
. In addition, its habitat is threatened by extensive deforestation
, dam
construction, land development, and water pollution
. These pressures are known to have caused declines in other freshwater stingray species, and therefore as a precaution the International Union for Conservation of Nature (IUCN) has listed this species as Endangered.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Dasyatidae, found over sandy bottoms in the Mae Klong
Mae Klong
The Mae Klong is a river in western Thailand. The river begins at the confluence of the Khwae Noi or Khwae Sai Yok and the Khwae Yai River or Khwae Si Sawat in Kanchanaburi, pass Ratchaburi Province and empties into the Gulf of Thailand in Samut Songkhram....
and Chao Phraya River
Chao Phraya River
The Chao Phraya is a major river in Thailand, with its low alluvial plain forming the centre of the country. It runs through Bangkok, the capital city, and then empties into the Gulf of Thailand.-Etymology:...
s of Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. Growing no more than 29 cm (11.4 in) across, this small ray has an oval pectoral fin disc and a whip-like tail without fin folds. It closely resembles the white-edge freshwater whipray
White-edge freshwater whipray
The white-edge freshwater whipray is an extremely rare species of stingray in the family Dasyatidae, native to four river systems in Southeast Asia. Measuring up to across, this ray has an oval pectoral fin disc and a very long, whip-like tail without fin folds...
(H. signifer) in appearance, but can be distinguished by its coloration: light gray to dark orange-brown above and white below with a dark band along the lateral margins. Another identifying feature is a "pearl organ" (enlarged dermal denticle) at the center of the back, found in individuals of all ages. All of the original specimens of the roughback whipray were found with extensive wounds to the fins and tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Endangered, citing the extensive habitat degradation and heavy fishing pressure within its limited range.
Taxonomy
The roughback whipray was described by WWF ThailandWorld Wide Fund for Nature
The World Wide Fund for Nature is an international non-governmental organization working on issues regarding the conservation, research and restoration of the environment, formerly named the World Wildlife Fund, which remains its official name in Canada and the United States...
Senior Freshwater Biologist Chavalit Vidthayanon and Smithsonian Research Associate Tyson Roberts in a 2005 issue of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Natural History Bulletin of the Siam Society. They named the ray after Bangkok
Bangkok
Bangkok is the capital and largest urban area city in Thailand. It is known in Thai as Krung Thep Maha Nakhon or simply Krung Thep , meaning "city of angels." The full name of Bangkok is Krung Thep Mahanakhon Amon Rattanakosin Mahintharayutthaya Mahadilok Phop Noppharat Ratchathani Burirom...
aquarium fish dealer and prominent fish expert Khun Jarutanin Kittipong, who the year before had provided the original five specimens that formed the basis for the description. A female 26 cm (10.2 in) across was designated as the type specimen. Based on morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, H. kittipongi seems to be most closely related to H. signifer, which shares its range.
Distribution and habitat
The original five specimens of the roughback whipray were all caught from the Mae Klong River in Kanchanaburi ProvinceKanchanaburi Province
- History :Archaeology found in Kanchanaburi dates back to the 4th century which proves of trade with surrounding countries even in that time. Very little is also historically known about the actual Khmer influence in Kanchanaburi but there is evidence of their occupation with Prasat Muang Singh –...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, in fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
above the influence of the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
. Additional records of this ray exist from the Chao Phraya River
Chao Phraya River
The Chao Phraya is a major river in Thailand, with its low alluvial plain forming the centre of the country. It runs through Bangkok, the capital city, and then empties into the Gulf of Thailand.-Etymology:...
, and perhaps the Penang River
Penang River
-References:*...
in Peninsular Malaysia
Peninsular Malaysia
Peninsular Malaysia , also known as West Malaysia , is the part of Malaysia which lies on the Malay Peninsula. Its area is . It shares a land border with Thailand in the north. To the south is the island of Singapore. Across the Strait of Malacca to the west lies the island of Sumatra...
. The total range of the roughback whipray is estimated to cover less than 5000 square kilometre. This bottom-dwelling species inhabits main river channels at a depth of 5–20 m (16.4–65.6 ft). In contrast to H. signifer, which favors muddy bottoms, it appears to favor sandy to silty substrates.
Description
The roughback whipray has a thin and oval pectoral fin disc slightly longer than wide, with the anterior margins converging at a broad angle to the tip of the snout. The snout terminates in a small, protruding knob, which is relatively larger than in H. signifer. The eyes are small and immediately followed by larger, teardrop-shaped spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s. There is a curtain of skin between the nostrils with a gently concave or lobed posterior margin. There are 4–5 papillae (nipple-like structures) across the floor of the small mouth. The small teeth are arranged in 4–5 series in the upper jaw and 14–15 series in the lower jaw; in some individuals, the outermost teeth are stained orange-brown. The whip-like tail lacks fin folds and bears one or two serrated, stinging spines on the upper surface, which are seldom found intact.
The dermal denticles are better-developed than those of H. signifer, with a central band of denticles covering the dorsal surface of the disc and tail base. There is also an enlarged "pearl organ" in the middle of the back that is present throughout life, and a row of enlarged denticles (some thorn-like) running from the pearl to the base of the sting. The disc is light gray or brown to dark orange-brown above, with a white to yellow spot just before the eyes and behind the spiracles, and sometimes a subtle, lighter band running around the margin. The underside of the disc is white, and unlike in H. signifer there is a dark (but not black) marginal band that extends from about one-third of the disc length back from the snout top, to the pelvic fins. The tail is gray to orange-brown above and white below at the base, becoming white with dark spots or nearly black past the sting. A small species, the largest known specimen is a female 29 cm (11.4 in) across.
Biology and ecology
All five original roughback whipray specimens bore extensive, healed wounds to the disc and/or pelvic fins, and had much of their tails bitten off such as that the remnant is only 1.3–1.8 times longer than the disc width (the tail of H. signifer measures over three times the disc width). This is in contrast to other freshwater stingrays in Thailand such as H. signifer, H. chaophraya and H. oxyrhynchaMarbled freshwater stingray
The marbled whipray is a little-known species of stingray in the family Dasyatidae, native to several freshwater rivers in Southeast Asia. This species has a oval pectoral fin disc with a elongated, pointed snout and a very long, whip-like tail without fin folds...
, which are usually found with their tails intact. Kittipong has proposed that these wounds are inflicted by pufferfish
Pufferfish
Tetraodontidae is a family of primarily marine and estuarine fish of the Tetraodontiformes order. The family includes many familiar species which are variously called pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies, honey toads, sugar toads, and sea squab...
es (Monotrete cf. leiurus and M. cf. nigroviridis); though plausible, why these wounds are seldom found on H. signifer remains a mystery. Another possibility is that the truncation of the tail is self-inflicted, which would be consistent with the similar lengths of the tail remnant in all five specimens. With a particularly small mouth, this species likely feeds on small crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and other benthic invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. Like other stingrays, it is aplacental viviparous with females provisioning their developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s with histotroph ("uterine milk"). Males reach sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at around 25 cm (9.8 in) across.
Human interactions
Uncommon and known only from a few locations, the roughback whipray faces intensive fishing pressure and is subject to incidental captureBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
in demersal tangle nets
Fishing net
A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...
, fish trap
Fish trap
A fish trap is a trap used for fishing. Fish traps may have the form of a fishing weir or a lobster trap. A typical trap might consist of a frame of thick steel wire in the shape of a heart, with chicken wire stretched around it. The mesh wraps around the frame and then tapers into the inside of...
s, and on hook-and-line. It may be sold as food like other freshwater stingrays in the region, or to the aquarium trade
Fishkeeping
Fishkeeping is a popular hobby concerned with keeping fish in a home aquarium or garden pond. There is also a fishkeeping industry, as a branch of agriculture.-Types of fishkeeping systems:...
. In addition, its habitat is threatened by extensive deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
, dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
construction, land development, and water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
. These pressures are known to have caused declines in other freshwater stingray species, and therefore as a precaution the International Union for Conservation of Nature (IUCN) has listed this species as Endangered.