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Mekong freshwater stingray : ウィキペディア英語版 | Mekong freshwater stingray
The Mekong freshwater stingray, ''Dasyatis laosensis'', is a species of stingray in the family Dasyatidae, restricted to the Mekong and Chao Phraya Rivers in Laos and Thailand; the occurrence in Chao Phraya is considered an introduction.〔 Measuring up to across, this ray has an oval pectoral fin disc, a tail with both upper and lower fin folds, and a midline row of spine-like dermal denticles. A characteristic feature of this species is its bright orange underside. The Mekong freshwater stingray preys on invertebrates and is aplacental viviparous. It has been assessed as Endangered by the International Union for Conservation of Nature (IUCN), as it is threatened by overfishing and habitat degradation. ==Taxonomy and phylogeny== The Mekong freshwater stingray was first recognized as a new species by Yasuhiko Taki, who included it as "''Dasyatis'' sp." in his 1968 list of Mekong River fishes from Laos. Taki's specimens were subsequently lost, and this ray was not formally described until 1987, by Tyson Roberts and Jaranthada Karnasuta, in the scientific journal ''Environmental Biology of Fishes''. The type specimen is an immature male across, caught from the Mekong in Chiang Rai Province, Thailand. A 1999 phylogenetic analysis, based on cytochrome b sequences, found that the Mekong freshwater stingray is closely related to an undescribed ''Dasyatis'' species from the Gulf of Thailand.
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