Brown stingaree
Encyclopedia
The brown stingaree is a little-known species
of stingray
in the family
Urolophidae, found at a depth of 60–220 m (196.9–721.8 ft) on the outer continental shelf
off northern Western Australia
. This species has a rhomboid
pectoral fin disc colored light yellow or brown, sometimes with three faint, darker, transverse bars. Its nostrils have a skirt-shaped curtain of skin between them. Its tail ends in a leaf-shaped caudal fin and either lacks or has poorly developed lateral skin folds and a dorsal fin
. The maximum known length is 36 cm (14.2 in). The International Union for Conservation of Nature (IUCN) has listed the brown stingaree under Least Concern
, as there is negligible fishing pressure across most of its range.
between the Dampier
and Bonaparte Archipelago
s. It is a benthic species that has been reported from a depth of 60–220 m (196.9–721.8 ft).
s with rounded posterior rims. The outer rim of each nostril may form a knob at the back. Between the nostrils is skirt-shaped curtain of skin, with a posterior margin that is very shallowly fringed and extended into small lobes each corner. There are 5–6 small papillae (nipple-like structures) on the floor of the fairly large mouth, along with a few papillae on the lower jaw. The small teeth have roughly oval bases. The five pairs of gill slit
s are short, and the pelvic fins are small and rounded.
The tail is rather short, measuring 66–80% as long as the disc, with a serrated stinging spine on top about halfway along its length and a short, deep, leaf-shaped caudal fin at the end. There may be subtle traces of a lateral skin fold on either side and a dorsal fin
in front of the sting. The skin is completely smooth. The upper surface is light yellow or brown in adults and light yellow in juveniles; there may be faint, darker bars running across the eyes, the gill region, and the middle of the back. The underside is whitish, and the caudal fin is yellow with a black margin. The largest known specimen measures 36 cm (14.2 in).
s sustained by histotroph ("uterine milk") produced by the mother. The litter size is probably small, as in related species. Newborns measure 10–13 cm (3.9–5.1 in) long; males mature sexually
at under 24 cm (9.4 in) long.
. Its population may have been affected by intensive foreign trawl fisheries that operated in the region from 1959 to 1990. It would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Urolophidae, found at a depth of 60–220 m (196.9–721.8 ft) on the outer continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
off northern Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. This species has a rhomboid
Rhomboid
Traditionally, in two-dimensional geometry, a rhomboid is a parallelogram in which adjacent sides are of unequal lengths and angles are oblique.A parallelogram with sides of equal length is a rhombus but not a rhomboid....
pectoral fin disc colored light yellow or brown, sometimes with three faint, darker, transverse bars. Its nostrils have a skirt-shaped curtain of skin between them. Its tail ends in a leaf-shaped caudal fin and either lacks or has poorly developed lateral skin folds and a dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
. The maximum known length is 36 cm (14.2 in). The International Union for Conservation of Nature (IUCN) has listed the brown stingaree under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
, as there is negligible fishing pressure across most of its range.
Taxonomy
Peter Last and Martin Gomon described the brown stingaree in a 1987 issue of Memoirs of the National Museum of Victoria. The type specimen is a male 19 cm (7.5 in) across, trawled from north of Port Hedland in Western Australia (hence the specific epithet westraliensis) by the FRV Soela on 2 April 1982. This species is closely related to the mitotic stingaree (U. mitosis).Distribution and habitat
Endemic to northern Western Australia, the brown stingaree is found over the outer continental shelfContinental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
between the Dampier
Dampier Archipelago
The Dampier Archipelago is a group of islands near Dampier, Western Australia. It is named after William Dampier, an English buccaneer and explorer who visited in 1699. Dampier named one of the islands, Rosemary Island.-History:...
and Bonaparte Archipelago
Bonaparte Archipelago
The Bonaparte Archipelago is a group of islands off the coast of Western Australia in the Kimberley region. The closest inhabited place is Kalumburu located about to the east of the island group....
s. It is a benthic species that has been reported from a depth of 60–220 m (196.9–721.8 ft).
Description
The pectoral fin disc of the brown stingaree is diamond-shaped and slightly wider than long, with broadly rounded outer corners. The anterior margins are nearly straight and converge at an obtuse angle on the snout, which protrudes slightly from the disc. The eyes are of modest size and followed by teardrop-shaped spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s with rounded posterior rims. The outer rim of each nostril may form a knob at the back. Between the nostrils is skirt-shaped curtain of skin, with a posterior margin that is very shallowly fringed and extended into small lobes each corner. There are 5–6 small papillae (nipple-like structures) on the floor of the fairly large mouth, along with a few papillae on the lower jaw. The small teeth have roughly oval bases. The five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s are short, and the pelvic fins are small and rounded.
The tail is rather short, measuring 66–80% as long as the disc, with a serrated stinging spine on top about halfway along its length and a short, deep, leaf-shaped caudal fin at the end. There may be subtle traces of a lateral skin fold on either side and a dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
in front of the sting. The skin is completely smooth. The upper surface is light yellow or brown in adults and light yellow in juveniles; there may be faint, darker bars running across the eyes, the gill region, and the middle of the back. The underside is whitish, and the caudal fin is yellow with a black margin. The largest known specimen measures 36 cm (14.2 in).
Biology and ecology
Little is known of the natural history of the brown stingaree. Reproduction is aplacental viviparous, with the developing embryoEmbryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s sustained by histotroph ("uterine milk") produced by the mother. The litter size is probably small, as in related species. Newborns measure 10–13 cm (3.9–5.1 in) long; males mature sexually
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at under 24 cm (9.4 in) long.
Human interactions
The range of the brown stingaree borders the area utilized by the North West Slope Trawl Fishery (NWSTF), but otherwise it faces no significant fishing pressure. Consequently, the International Union for Conservation of Nature (IUCN) has listed this species under Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
. Its population may have been affected by intensive foreign trawl fisheries that operated in the region from 1959 to 1990. It would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.