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Diamond stingray
The diamond stingray (''Dasyatis dipterura'') is a species of stingray in the family Dasyatidae. It is found in the coastal waters of the eastern Pacific Ocean from southern California to northern Chile, and around the Galápagos and Hawaiian Islands. This bottom-dweller generally inhabits sandy or muddy flats near rocky reefs and kelp forests, to a depth of , though off Hawaii it may range considerably deeper. As its common name suggests, this species has an angular, diamond-shaped pectoral fin disc that is plain brown or gray above, with rows of tubercles along the midline and on the "shoulders". The long, whip-like tail has both dorsal and ventral fin folds, which distinguish this ray from the closely similar longtail stingray (''D. longa''). It typically grows to across.
When searching for food, diamond stingrays may form groups of up to hundreds of individuals. It is most active at night and preys mainly on burrowing invertebrates and small bony fishes, which are extracted from the bottom via suction or digging. This species is aplacental viviparous: once the embryos exhaust their yolk supply, they are nourished by histotroph ("uterine milk") produced by the mother. Females bear 1–4 pups every summer in estuaries; mating is followed by a ten-month period of either sperm storage or arrested embryonic development, after which the embryos rapidly mature over 2–3 months. The slowest-growing stingray known, this species is not resilient against fishing pressure. It is caught for food by artisanal fishers in Latin America, particularly in Mexico where it is one of the most economically important rays. This has led it to be assessed as Near Threatened in Mexico by the International Union for Conservation of Nature (IUCN), while the species as a whole is listed as Data Deficient. Though innocuous towards humans, the diamond stingray's long, venomous tail spine is potentially dangerous.
==Taxonomy and phylogeny==
In 1880, the diamond stingray was described twice by three American ichthyologists: as ''Dasybatus dipterurus'' by David Starr Jordan and Charles Henry Gilbert in ''Proceedings of the United States National Museum'', and as ''Trygon brevis'' by Samuel Garman in ''Bulletin of the Museum of Comparative Zoology''.〔〔 Jordan and Gilbert's account was published in May while Garman's was published in October, making ''dipterurus'' (feminine ''dipterura'') the correct name as it was published first. However, when Garman synonymized the two in 1913 he inappropriately gave precedence to ''brevis'', leading to long-standing confusion.〔 Both ''Dasybatus'' and ''Trygon'' were later synonymized with the genus ''Dasyatis'', but many authors still listed ''D. brevis'' in place of or in addition to ''D. dipterura''.〔〔 Garman also synonymized the Hawaiian stingray (''D. hawaiensis'') with ''D. dipterura'' in 1913, which has since been followed by most authors but requires more study for confirmation.〔
The species syntypes were collected from San Diego Bay, California.〔 The specific epithet ''dipterura'' is derived from the Latin ''di'' ("two"), ''ptero'' ("wing"), and ''ura'' ("tail"), referring to the fin folds on both sides of its tail. Rat-tailed stingray is a former common name for this species.〔 Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology, determined the diamond stingray and the bluntnose stingray (''D. say'') of the western Atlantic Ocean to be sister species, that likely diverged before or with the formation of the Isthmus of Panama (''c.'' 3 Ma). In addition, the two were found to be the second-most basal taxa in their genus, after the common stingray (''D. pastinaca'').〔
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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