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Pacific chupare
The Pacific chupare or Pacific whiptail stingray, ''Himantura pacifica'', is a species of stingray in the family Dasyatidae. It has been reported off the Pacific coast of Central America from Oaxaca, Mexico to Costa Rica, and also around the Galapagos Islands. It is usually found in shallow water on soft silty or muddy flats; it is unknown whether this species is tolerant of low salinity like the related chupare stingray (''H. schmardae'').〔〔 Leonard Compagno doubted the taxonomic validity of this species in his 1999 ''Checklist of Living Elasmobranchs''.
This stingray attains a maximum known length of and a disk width of . It has a rounded pectoral fin disk and a broadly angled snout with a small protuberance at the tip. The tail lacks fin folds but has a low ventral keel. The dorsal surface of the body and tail are covered with rough dermal denticles. There are large tubercles with four radial ridges on the shoulder region.〔 A venomous spine is present on the tail.〔 Known parasites of this species include the nematode ''Echinocephalus janzeni'' and the cestodes ''Acanthobothroides pacificus'' and ''Rhinebothrium geminum''. Reproduction is ovoviviparous.〔
The Pacific chupare and the chupare stingray in the Atlantic are believed to be sister species, together referred to as the "amphi-American ''Himantura''". The two species are morphologically similar and share four-ridged shoulder tubercles. Based on the details of the mandibular musculature and articulation, the amphi-American ''Himantura'' are hypothesized to be most closely related to the river stingrays in the family Potamotrygonidae, rather than to Indo-Pacific ''Himantura'' species.〔 This has given rise to the theory that both the amphi-American ''Himantura'' and the river stingrays are descended from euryhaline ancestors living along the northern coast of South America prior to the formation of the Isthmus of Panama. However, this interpretation is disputed, as parasitological evidence suggests that the river stingrays are most closely related to Pacific ''Urobatis'' stingrays.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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