The wide stingaree (''Urolophus expansus'') is a little-known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of stingray in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Urolophidae The Urolophidae are a family of rays in the order Myliobatiformes, commonly known as stingarees or round stingrays. This family formerly included the genera '' Urobatis'' and '' Urotrygon'' of the Americas, which are presently recognized as formi ...

, found off southwestern Australia. It typically occurs over sand in water deep around the edge of the continental shelf. This species has a broad diamond-shaped

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

disc, a slightly pointed snout, and a tail with a leaf-like

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

, skin folds along either side, and no

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s. Between its nostrils is a skirt-shaped curtain of skin. It is grayish green above, with faint bluish lines beside and behind the eyes. The maximum length on record is . The diet of the wide stingaree consists mainly of isopods and

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

s. It is

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop ins ...

, with the females supplying their unborn young with histotroph ("

uterine The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

milk"). This species is regularly caught incidentally by commercial

trawl Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different speci ...

fisheries operating in the

Great Australian Bight The Great Australian Bight is a large oceanic bight, or open bay, off the central and western portions of the southern coastline of mainland Australia. Extent Two definitions of the extent are in use – one used by the International Hydrog ...

. Although it is unlikely to survive being captured and also tends to abort any

gestating Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnanc ...

young during the process, large portions of the wide stingaree's range see little to no fishing activity and overall the species is not threatened. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

(IUCN) has listed it under

Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

Taxonomy

The first known specimens of the wide stingaree were collected from the

by the research vessel FIS ''Endeavour'', and described by Australian ichthyologist Allan Riverstone McCulloch in a 1916 volume of the scientific journal ''Biological Results Endeavour''. The specific epithet ''expansus'' means "spread out" or "expanded" in

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

. Another common name for this species is broadbacked stingaree.

Distribution and habitat

The wide stingaree is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to southwestern Australia, occurring from

Perth Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth i ...

, Western Australia to

Port Lincoln, South Australia Port Lincoln is a town on the Lower Eyre Peninsula in the Australian state of South Australia. It is situated on the shore of Boston Bay, which opens eastward into Spencer Gulf. It is the largest city in the West Coast region, and is located a ...

. One of the deeper-living representatives of its family, this benthic species inhabits the outer continental shelf and upper

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

at a depth of . It is most commonly found between down, over sandy areas. There is evidence for some degree of segregation by age and sex.

Description

The wide stingaree has a diamond-shaped

disc much wider than long, with broadly rounded outer corners and trailing margins. The anterior margins are gently sinuous and converge at an obtuse angle on the fleshy, slightly protruding snout. The eyes are large and immediately followed by comma-shaped spiracles with rounded posterior margins. There is a skirt-shaped curtain of skin with a shallowly fringed posterior margin between the nostrils. The mouth is of medium size and contains 6–9 papillae (nipple-like structures) on the floor; a narrow patch of papillae is also found on the lower jaw. The teeth are small with roughly oval bases. The five pairs of

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 and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s are short. The pelvic fins are small, with rounded edges. The tail measures 71–93% as long as the disc and has a highly flattened base and well-developed lateral skin folds; there is no

, while the terminal

is lance-like and elongated. A serrated stinging spine is placed atop the tail about halfway along its length. The skin is completely smooth. This species is dusky green above, with two faint, bluish transverse lines behind the eyes and a pair of similar lines running obliquely outwards from the eyes. The underside is white to beige, darkening towards the disc lateral margins, with dark blotches on the tail. Juveniles have a dark caudal fin. The largest known specimen measures long.

Biology and ecology

The wide stingaree is a poorly known species that preys mainly on isopods and

s. Like other stingrays, it is

, with the developing embryos sustained by histotroph ("

milk"). The litter size is probably small as in related species. Males mature sexually at a disc width of and seven years of age, and have a maximum lifespan of 11 years. Females mature at a disc width of about . A known

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

of this species is a

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cesto ...

of the genus ''Acanthobothrium''.

Human interactions

Edible though not marketed, the wide stingaree is caught incidentally on a regular basis in

otter trawl Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is towin ...

s utilized by the Great Australian Bight Trawl Sector of the Southern and Eastern Scalefish and Shark Fishery (SESSF), and to a much lesser extent by the small-scale Western Deepwater Trawl Fishery (WDWTF) in the westernmost portion of its range. Captured individuals are unlikely to survive as they are brought up from such great depths, and furthermore stingarees have a tendency to abort their young when captured. However, the SESSF only operates over part of the Great Australian Bight, and so the overall level of fishing pressure across the wide stingaree's range is low. Therefore, the

(IUCN) has assessed this species as of

References

External links

Fishes of Australia : ''Urolophus expansus''
{{Taxonbar, from=Q3281018 wide stingaree Fauna of South Australia Marine fish of Southern Australia Taxa named by Allan Riverstone McCulloch wide stingaree Taxonomy articles created by Polbot