Australian reticulate swellshark
Encyclopedia
The Australian reticulate swellshark (Cephaloscyllium hiscosellum) is a little-known species
of catshark
, family
Scyliorhinidae, found off northwestern Australia
at a depth of 290–420 m (951.4–1,378 ft). This shark has a stocky body and a short, wide head with a capacious mouth. It is characterized by a striking dorsal color pattern of dark brown lines that trace a series of hollow saddles and narrow rings, on a light background. Like other swellsharks, this species can inflate itself when threatened. Reproduction is oviparous.
(C. fasciatum) of Vietnam
and Hainan
, the Australian reticulate swellshark was described as a separate species by William White and David Ebert in a 2008 Commonwealth Scientific and Industrial Research Organisation
(CSIRO) publication. Its specific epithet hiscosellum is derived from the Latin
hisco meaning "open", and sella meaning "saddle", referring to its distinctive color pattern. The type specimen is a 46 cm (18.1 in) long adult male caught west of Leander Point, Western Australia
.
and Broome
. It occurs at a depth of 290–420 m (951.4–1,378 ft).
s preceded by laterally expanded skin flaps that do not reach the mouth. The slit-like eyes are placed high on the head, and are followed by tiny spiracle
s. The mouth is long, wide, and strongly arched, without furrows at the corners; the upper teeth are exposed when the mouth is closed. There are 49–63 upper tooth rows and 45–60 lower tooth rows. Females have much smaller teeth than males of comparable size; each tooth has three cusps and rarely 1–2 additional lateral cusplets. The fourth and fifth pairs of gill slit
s lie over the pectoral fin bases and are shorter than the first three.
The pectoral fins are fairly small, narrow, and angular. The pelvic fins are small, with long, elongate claspers in males. The first dorsal fin
has a rounded apex and originates over the posterior half of the pelvic fin bases. The second dorsal fin is much smaller and roughly triangular. The rounded to angular anal fin is substantially larger than, and placed slightly behind, the second dorsal fin. The caudal fin is moderately large, with a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. The dermal denticles are tiny and arrowhead-shaped, with a median ridge in males and both median and lateral ridges in females. This shark is light grayish to brownish above, with narrow dark lines that form a series of open-centered saddles and narrow rings from the head to the tail; some individuals have small, scattered yellow spots or a dark ring or spot atop each pectoral fin. The underside is a uniform beige.
between a length of 39–46 cm (15.4–18.1 in).
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 catshark
Catshark
Catsharks are ground sharks of the family Scyliorhinidae, with over 150 known species. While they are generally known as catsharks, many species are commonly called dogfish....
, 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...
Scyliorhinidae, found off northwestern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
at a depth of 290–420 m (951.4–1,378 ft). This shark has a stocky body and a short, wide head with a capacious mouth. It is characterized by a striking dorsal color pattern of dark brown lines that trace a series of hollow saddles and narrow rings, on a light background. Like other swellsharks, this species can inflate itself when threatened. Reproduction is oviparous.
Taxonomy
Once thought to be the same species as the reticulated swellsharkReticulated swellshark
The reticulated swellshark, Cephaloscyllium fasciatum, is a catshark of the family Scyliorhinidae found in the western Pacific Ocean between latitudes 21° N and 28° S, at depths of between 220 and 450 m. It grows to about 42 cm in length....
(C. fasciatum) of Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and Hainan
Hainan
Hainan is the smallest province of the People's Republic of China . Although the province comprises some two hundred islands scattered among three archipelagos off the southern coast, of its land mass is Hainan Island , from which the province takes its name...
, the Australian reticulate swellshark was described as a separate species by William White and David Ebert in a 2008 Commonwealth Scientific and Industrial Research Organisation
Commonwealth Scientific and Industrial Research Organisation
The Commonwealth Scientific and Industrial Research Organisation is the national government body for scientific research in Australia...
(CSIRO) publication. Its specific epithet hiscosellum is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
hisco meaning "open", and sella meaning "saddle", referring to its distinctive color pattern. The type specimen is a 46 cm (18.1 in) long adult male caught west of Leander Point, 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...
.
Distribution and habitat
The range of the Australian reticulate swellshark is limited to the upper continental slope off northwestern Australia, between GeraldtonGeraldton, Western Australia
Geraldton is a city and port in Western Australia located north of Perth in the Mid West region. Geraldton has an estimated population at June 2010 of 36,958...
and Broome
Broome, Western Australia
Broome is a pearling and tourist town in the Kimberley region of Western Australia, north of Perth. The year round population is approximately 14,436, growing to more than 45,000 per month during the tourist season...
. It occurs at a depth of 290–420 m (951.4–1,378 ft).
Description
Male and female Australian reticulate swellsharks are known to attain lengths of 46 cm (18.1 in) and 52 cm (20.5 in) respectively. This species has a stocky body and a short, broad, and strongly flattened head. The snout is broadly rounded, with the nostrilNostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s preceded by laterally expanded skin flaps that do not reach the mouth. The slit-like eyes are placed high on the head, and are followed by tiny spiracle
Spiracle
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. The mouth is long, wide, and strongly arched, without furrows at the corners; the upper teeth are exposed when the mouth is closed. There are 49–63 upper tooth rows and 45–60 lower tooth rows. Females have much smaller teeth than males of comparable size; each tooth has three cusps and rarely 1–2 additional lateral cusplets. The fourth and fifth 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 lie over the pectoral fin bases and are shorter than the first three.
The pectoral fins are fairly small, narrow, and angular. The pelvic fins are small, with long, elongate claspers in males. The first 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...
has a rounded apex and originates over the posterior half of the pelvic fin bases. The second dorsal fin is much smaller and roughly triangular. The rounded to angular anal fin is substantially larger than, and placed slightly behind, the second dorsal fin. The caudal fin is moderately large, with a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. The dermal denticles are tiny and arrowhead-shaped, with a median ridge in males and both median and lateral ridges in females. This shark is light grayish to brownish above, with narrow dark lines that form a series of open-centered saddles and narrow rings from the head to the tail; some individuals have small, scattered yellow spots or a dark ring or spot atop each pectoral fin. The underside is a uniform beige.
Biology and ecology
Little is known of the natural history of the Australian reticulate swellshark. Like other members of its genus, this species can inflate itself with water or air as a defensive measure. The eggs of this oviparous species are contained in smooth, light yellow flask-shaped capsules, which have a flanged margin and horns at the corners that support long, coiled tendrils. The hatchlings seem to lack the specialized denticle used by other swellsharks to break out of the egg case. Males mature sexuallySexual 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...
between a length of 39–46 cm (15.4–18.1 in).