Brazilian large-eyed stingray
The Brazilian large-eyed stingray, Hypanus marianae, is a species of stingray in the family Dasyatidae. Endemic to northeastern Brazil, adults of this species inhabit shallow coral and sandstone reefs while the young are also found near beaches and in estuaries. This stingray measures up to across and can be identified by its large eyes, equally long fin folds above and below the tail, and distinctive coloration consisting of various dark brown markings on a yellowish-brown background above, and two pairs of dark brown blotches on a white background below. Reproduction is aplacental viviparous, with females giving birth to one young at a time, twice a year, and using sandbanks as nursery areas. The Brazilian large-eyed stingray is collected by artisanal fisheries and for the ornamental fish trade.
Taxonomy and phylogeny
The Brazilian large-eyed stingray was described by Ulisses Gomes, Ricardo Rosa, and Otto Gadig in 2000, in the scientific journal Copeia. The authors originally intended to name the ray Dasyatis macrophthalma, but at the eleventh hour it was discovered that this name was a nomen nudum already used in an earlier paper by Ivan Sazima and Rodrigo Moura. The specific epithet for the new stingray was thus changed to marianae, in honor of Dr. Gadig's daughter Mariana Gadig, which was applied throughout the published description except in the title, where it remained macrophthalma. The authors corrected this mistake under the Principle of the First Reviser. The type specimen is a long male caught off Recife, Brazil.In 2006, Leticia de Almeida Leao Vaz and colleagues published a phylogenetic analysis, based on genomic DNA, of the Brazilian large-eyed stingray and three other common stingrays found off Brazil: the southern stingray, the longnose stingray, and the roughtail stingray. They found that H. marianae is sister to a group containing H. americana and Bathytoshia centroura.
Distribution and habitat
The range of the Brazilian large-eyed stingray extends along the coast of northeastern Brazil from Parcel Manoel Luís off Maranhão state to southern Bahia, though more sampling may reveal a wider distribution for this species. Occurring at depths of, adult rays are closely associated with coral or sandstone reefs on the continental shelf, and have also been observed around shipwrecks. Younger rays inhabit nearshore sandy flats and estuaries in addition to reefs.Description
The Brazilian large-eyed stingray has a diamond-shaped pectoral fin disc approximately as long as wide, with rounded outer corners and slightly concave front margins. The tip of the snout is not strongly projecting. The eyes are large, about equal in width to the spiracles and the distance between the eyes. The mouth is small, with a transverse row of three papillae on the floor. There are 35-45 tooth rows in the upper jaw and 38-48 tooth rows in the lower jaw. The teeth of juveniles and females are blunt, while those of older males are pointed. The tail measures no longer than 1.5 times the disc width, and tapers to a filament towards the tip. There is a stinging spine on top of the tail, followed by dorsal and ventral fin folds of roughly equal length; the dorsal fold is up to twice as tall as the ventral fold.The disc is mostly smooth, except for a row of 2-18 small, thornlike dermal denticles along the dorsal midline in adults and a single thorn on each "shoulder" in males. The coloration of this species is distinctive: the back is golden brown with the disc and pelvic fins edged by a thin blue line and then a dark brown band. There are dark brown blotches around the eyes, between the spiracles, and in two pairs behind the spiracles and further back on the disc. Adult males have blue coloring on top and at the tip of the claspers. The underside is white, darkening at the disk margin, with a pair of dark brown kidney-shaped blotches outside the gill slits, paired patches of lighter brown, irregular blotches further back, and sometimes a single dark spot at the center of the disc. The tail is brown above and white below, darkening to purple at the tip, with the fin folds dark brown and edged in blue. The largest known specimen is across, though individuals across have been seen in the wild.