The saddled swellshark (''Cephaloscyllium variegatum'') is a rare

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 catshark, and part of 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 ...

Scyliorhinidae,

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 elsew ...

to Eastern Australia. This bottom-dwelling species is found on the outer

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

and upper continental slope at a depth of . It is a robustly built shark with a short, broad, flattened head and a capacious mouth. Adults are patterned with saddles on a brownish or grayish background, which varies between

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

sharks; juveniles are light-colored with many spots. This shark reaches in length. Like other swellsharks, it can inflate itself as a defensive measure. Reproduction is

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

Taxonomy

In 1994, Commonwealth Scientific and Industrial Research Organisation (CSIRO) chief researchers Peter Last and John Stevens recognized five undescribed swellsharks in Australian waters. Later investigation revealed that the forms provisionally named ''Cephaloscyllium'' "sp. B" and "sp. C" may represent clinal variants of a single species, which was described by Peter Last and William White in a 2008 CSIRO publication. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''variegatum'' comes from the

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 ...

word for "various", and refers to the large amount of color variation within this species. The

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

is long adult male, collected from east of

Newcastle, New South Wales Newcastle ( ; Awabakal: ) is a metropolitan area and the second most populated city in the state of New South Wales, Australia. It includes the Newcastle and Lake Macquarie local government areas, and is the hub of the Greater Newcastle area, w ...

Description

The saddled swellshark reaches a maximum known length of . It has a moderately stocky body and a short, variably wide, and strongly flattened head. The snout is broadly rounded, with the nostrils preceded by laterally expanded flaps of skin that do not reach the large mouth. The slit-like eyes are positioned high on the head and followed by tiny

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. The tooth rows number 68–82 in the upper jaw and 68–80 in the lower jaw. The very small teeth have three cusps, with the central one the longest and sometimes 1–2 additional lateral cusplets. In females the central cusp is smaller than in males. There are no furrows at the corners of the mouth, and the upper teeth are exposed when the mouth is closed. The fourth and fifth

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 lie over the

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 ...

bases and are shorter than the first three. The pectoral fins are large and broad, with rounded margins. The first

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 ...

is fairly angular and originates over the middle of 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 ...

bases. The second dorsal fin is much smaller and lower than the first, originating behind the

anal 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 ...

origin. The pelvic fins are small, with elongate, relatively short

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's ...

in males. The anal fin is substantially larger and deeper than the second dorsal fin. The

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 ...

is deep, with a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. The body is densely covered by minute

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s, each shaped like an arrowhead and bearing a median ridge. The saddled swellshark is brownish or grayish in color above, with 11 darker saddles of varying width over the body and tail and usually no blotches on the flanks. Individuals from tropical waters ("sp. B") tend to have more defined saddles, while those from temperate waters ("sp. C") have fainter saddles and a smattering of lighter flecks. The underside is a plain light color, often with a few darker marks. The juveniles are pale with many dark brown spots.

Distribution and habitat

The saddled swellshark is found off the eastern coast of Australia, as far north as

Rockingham Bay Rockingham Bay is a bay in Far North Queensland, Australia. The bay opens onto the Coral Sea, part of the South Pacific Ocean. Adjacent to the bay is the Girramay National Park, south of which is the town of Cardwell. Goold Island is a smal ...

in Queensland and as far south as Tathra in New South Wales, and perhaps also the Britannia Seamount near

Brisbane Brisbane ( ) is the capital and most populous city of the states and territories of Australia, Australian state of Queensland, and the list of cities in Australia by population, third-most populous city in Australia and Oceania, with a populati ...

. It is a bottom-dwelling species that inhabits the outer

and upper continental slope at a depth of .

Biology and ecology

Like other members of its genus, the variegated swellshark can inflate itself with water or air as a defensive measure. This species is

, with its eggs contained in smooth, brownish capsules about long. The egg capsule is thick and rounded, with flanged lateral margins and a pair of horns at each end, which support very long, coiled tendrils. The smallest known free-swimming specimen measured long; males

mature sexually Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definiti ...

at a length of .

Human interactions

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) has listed the saddled swellshark under

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

until more information is available. Currently, little fishing occurs in the region where this shark is found, but should that change it may be vulnerable due to its apparent rarity and benthic habits.

References

{{Taxonbar, from=Q1151176 Cephaloscyllium Fish of Australia Fish described in 2008 Taxa named by Peter R. Last Taxa named by William Toby White Taxonomy articles created by Polbot