Greenback stingaree
The greenback stingaree is a little-known species of stingray in the family Urolophidae, endemic to the outer continental shelf and upper continental slope off southeastern Australia. Growing to a length of, this species has a diamond-shaped pectoral fin disc wider than long and uniformly light green in color above. Between its nostrils is a skirt-shaped curtain of skin. Its tail bears skin folds on either side and a deep, lanceolate caudal fin, but lacks a dorsal fin.
Usually found over soft substrates at a depth of, the greenback stingaree is a predator of polychaete worms and crustaceans. It is aplacental viviparous, with developing embryos are sustained by maternally produced histotroph. Females bear litters of 1-3 pups annually after a 10-12 month gestation period. Substantial numbers of greenback stingarees are caught incidentally in trawls; captured rays rarely survive and also tend to abort their young. Stingaree populations on the New South Wales upper slope, presumably including this species, have declined precipitously as a result of commercial fishing. Consequently, the International Union for Conservation of Nature has listed the greenback stingaree as Vulnerable.
Taxonomy
The greenback stingaree was described by Australian ichthyologist Allan Riverstone McCulloch in a 1916 volume of the scientific journal Biological Results Endeavour, who gave it the specific epithet viridis from the Latin word for "green". The type specimen was collected from a depth of off Green Cape in New South Wales, by the research vessel FIS Endeavour. An undescribed stingaree possibly belonging to this species has also been found in deep water off southwestern Australia; it is very similar to the greenback stingaree but has more pectoral fin rays.Distribution and habitat
Once common, the greenback stingaree occurs in warm-temperate waters from Portland in Victoria to Stradbroke Island off Queensland, including all of Tasmania. Deeper-living than most other stingarees in the region, this benthic species is mainly found over fine sediment at a depth of on the outer continental shelf and upper continental slope. However, it has been reported from as shallow as and as deep as.Description
The greenback stingaree has a diamond-shaped pectoral fin disc wider than long, with broadly rounded outer corners. The leading margins of the disc are nearly straight, and converge at an obtuse angle on the fleshy snout. The tip of the snout protrudes slightly past the disc. The eyes are large and followed by comma-shaped spiracles with rounded posterior margins. There is a skirt-shaped curtain of skin between the nostrils, with a finely fringed posterior margin; the posterior corners of the nasal curtain are extended into small lobes. The medium-sized mouth contains 4-7 variably shaped papillae on the floor; additional papillae are found in a narrow strip on the lower jaw. The teeth are small with roughly oval bases, and the five pairs of gill slits are short. The pelvic fins are small and rounded on their trailing margins.The tail is flattened at the base and measures 75-91% as long as the disc; a prominent skin fold runs along each side, and a deep, lance-shaped caudal fin is found at the end. The upper surface of the tail bears a serrated stinging spine about halfway along its length; there is no dorsal fin. The skin entirely lacks dermal denticles. This species is a plain light green above, becoming lighter towards the edge of the disc, and off-white below, becoming purplish or pinkish towards the lateral margins of the disc; the ventral, lateral disc margins may also have a dark brown edge or blotches. The caudal fin is colored dark brown in juveniles and olive in adults. Some individuals are dark beneath the tail and/or on the tip of the snout. The maximum recorded length is.