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Sharpsnout stingray
The sharpsnout stingray or wingfin stingray, ''Dasyatis geijskesi'', is a species of stingray in the family Dasyatidae, found from off Venezuela to northern Brazil. It inhabits shallow, brackish water, shifting towards the coast in the dry season and away from it in the rainy season. Typically measuring across, this dark brown ray is easily identifiable by its long, projecting snout and elongated, acutely pointed pelvic fins. Its diet consists of bottom-dwelling invertebrates. Reproduction is aplacental viviparous, with females bearing one to three pups annually. Naturally uncommon and slow-reproducing, the sharpnose stingray is under pressure by both artisanal and commercial fisheries, leading the International Union for Conservation of Nature (IUCN) to assess it as Near Threatened.
==Taxonomy and phylogeny==
Dutch ichthyologist Marinus Boeseman described the sharpsnout stingray in a 1948 issue of the scientific journal ''Zoologische Mededelingen'', based on a juvenile male caught off Suriname with a disc length of . The whereabouts of this type specimen is unknown.〔(Catalog of Fishes (Online Version) ). California Academy of Sciences. Retrieved on November 24, 2009.〕 In a 2001 phylogenetic analysis based on morphological characters, Lisa Rosenberger found that the longnose stingray (''D. guttata'') is the sister species of the sharpsnout stingray, and that the two form a clade with the pale-edged stingray (''D. zugei''), the pearl stingray (''D. margaritella''), the sharpnose stingray (''Himantura gerrardi''), and the smooth butterfly ray (''Gymnura micrura'', included in the study as an outgroup). These results support the growing consensus that neither ''Dasyatis'' nor ''Himantura'' are monophyletic.
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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