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Roughtail stingray
The roughtail stingray (''Dasyatis centroura'') is a species of stingray in the family Dasyatidae, with separate populations in coastal waters of the northwestern, eastern, and southwestern Atlantic Ocean. This bottom-dwelling species typically inhabits sandy or muddy areas with patches of invertebrate cover, at a depth of . It is seasonally migratory, overwintering in offshore waters and moving into coastal habitats for summer. The largest whip-tail stingray in the Atlantic,〔 the roughtail stingray grows up to across and in weight. It is plain in color, with an angular, diamond-shaped pectoral fin disc and a long, whip-tail tail bearing a subtle fin fold underneath. The many thorns on its back and tail serve to distinguish it from other stingrays that share its range.
Often found lying on the bottom buried in sediment, the roughtail stingray is a generalist predator that feeds on a variety of benthic invertebrates and bony fishes. It is aplacental viviparous, with the embryos receiving nourishment initially from yolk, and later from histotroph ("uterine milk") produced by the mother. In the northwestern Atlantic, females bear an annual litter of 4–6 young in fall and early winter, after a gestation period of 9–11 months. By contrast, in the Mediterranean there is evidence that females bear two litters of 2–6 young per year after a gestation period of only four months. Rays in the northwestern Atlantic are also larger at birth and at sexual maturity than those from the Mediterranean. The venomous tail spine of the roughtail stingray is potentially dangerous to humans. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern overall and in the northwestern Atlantic, where it is not commercially utilized. However, in the Mediterranean and southwestern Atlantic it is subject to heavy fishing pressure and has been assessed as Near Threatened.
== Taxonomy and phylogeny ==
The first description of the roughtail stingray was published by American naturalist Samuel Mitchell in one of the earliest North American works on ichthyology, a short treatise on the fishes of New York in the 1815 first volume of ''Transactions of the Literary and Philosophical Society of New York''.〔〔 Mitchell based his account on specimens caught off Long Island, though did not designate any types, and named the new species ''Raja centroura'', from the Greek ''centoro'' ("pricker") in reference to its thorns. Subsequent authors moved this species to the genus ''Dasyatis''.〔〔 This ray may also be referred to as rough-tailed stingray, rough-tailed northern stingray, or thorny stingray.〔〔
The taxonomy of the roughtail stingray is not fully resolved, with the disjunct northwestern Atlantic, southwestern Atlantic, and eastern Atlantic populations differing in life history and perhaps representing a complex of different species.〔 Lisa Rosenberger's 2001 phylogenetic analysis of 14 ''Dasyatis'' species, based on morphology, found that the roughtail stingray is the sister species to the broad stingray (''D. lata''), and that they form a clade with the southern stingray (''D. americana'') and the longtail stingray (''D. longa'').〔 The close relationship between the roughtail and southern stingrays was upheld by a genetic analysis published by Leticia de Almeida Leao Vaz and colleagues in 2006.〔 The roughtail and broad stingrays are found in the Atlantic and Pacific Oceans respectively, and therefore likely diverged before or with the formation of the Isthmus of Panama (''c.'' 3 Ma).〔
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