The Kai stingaree (''Urolophus kaianus'') is a

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 ...

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae ( ...

in the

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

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 formin ...

, known only from two juveniles collected from deep in the Kai Islands of eastern

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. This species has a rhomboid

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 ...

with a very blunt, rounded snout, and a tail with lateral skin folds, a leaf-shaped

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 se ...

, 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 conv ...

. It is brown above with blackish coloring on the upper surface of each eyeball. The larger of the two specimens measures long. 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 natu ...

(IUCN) does not yet have enough information to assess the Kai stingaree beyond

Data Deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

. It presently faces little fishing, though this is liable to change in the future.

Taxonomy

From September 9 to 29, 1874, the research ship HMS ''Challenger'' collected a number of hitherto-unknown fishes from Station 192 in the Kai Islands, including two specimens of the Kai stingaree. British

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

Albert Günther Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther (3 October 1830 – 1 February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked the second-most productive re ...

wrote a brief description of the new species and published it in 1880, as part of the scientific reports that followed the ''Challenger'' expedition.

Distribution and habitat

The two Kai stingaree specimens were collected over blue

mud A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...

in the Kai Islands, at a depth of . Given that no further specimens have emerged since the originals, it seems to be extremely rare and/or have a highly restricted range.

Description

The

disc of the Kai stingaree is diamond-shaped and much wider than long, with narrowly rounded outer corners. The leading margins of the disc converge at an obtuse angle on the snout, which is rounded and non-protruding. The eyes are immediately followed by teardrop-shaped

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s. Between the nostrils is a skirt-shaped curtain of skin, whose posterior corners are extended into small lobes. 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, and the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s are small with rounded margins. The tail is slightly shorter than the disc, bearing a skin fold running along either side and a leaf-shaped

at the end. A serrated stinging spine is placed on top, about halfway along the tail's length; there is no

. The skin is completely smooth. This species is a plain yellowish brown above, transitioning sharply to blackish on the upper surface of each eyeball. The two specimens are both juveniles, one measuring and the other in length.

Biology and ecology

Virtually nothing is known of the natural history of the Kai stingaree. It is presumably

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 insi ...

with a small litter size, like other stingarees.

Human interactions

The

(IUCN) currently has insufficient data to assess the Kai stingaree beyond

. Indonesian

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 Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

do not presently operate below a depth of , though this is anticipated to change in the future, at which time this species may be threatened.

References

{{Taxonbar, from=Q5033547 Urolophus Fish of Indonesia Taxonomy articles created by Polbot Fish described in 1880 Taxa named by Albert Günther