Flagtail swellshark
Encyclopedia
The flagtail swellshark (Cephaloscyllium signourum) is a little-known species
of catshark
, family
Scyliorhinidae, found at a depth of 480–700 m (1,574.8–2,296.6 ft) off northeastern Queensland
and possibly also nearby islands. This stout-bodied shark has a short, broad, and flattened head with a capacious mouth. Adults have a variegated brown coloration with 9–10 darker dorsal saddles and "V"-shaped blotch at the tip of the upper caudal fin lobe. Juveniles are yellow with narrow brown bars instead of saddles, and a distinctive marking between the spiracle
s shaped like two loops connected by a line. Like other swellsharks, this species can inflate its body when threatened.
(CSIRO) chief researchers Peter Last and John Stevens recognized an undescribed Australia
n swellshark with a variegated color pattern, which they provisionally named Cephaloscyllium "sp. E". Later investigation revealed that "sp. E" in fact constituted two species: the speckled swellshark (C. speccum) and the flagtail swellshark, which was formally described in a 2008 CSIRO publication by Peter Last, Bernard Séret, and William White. In reference to its distinctive caudal fin marking, the shark was given the specific epithet signourum from the Latin
signum ("flag") and the Greek
oura ("tail"). The type specimen is a 74 cm (29.1 in) long female collected at the Lihou Reef and Cays, near Queensland
.
, Vanuatu
, and Fiji
may also be of this species as they closely resemble Australian specimens, but differ in some morphometric counts. This bottom-dwelling shark occurs at a depth of 480–700 m (1,574.8–2,296.6 ft).
prove to be conspecific with those from Australia, then this species can grow to over 1 m (3.3 ft) long. It has a fairly stout body and a short, very broad, and strongly flattened head. The snout is rounded, with nostril
s preceded by laterally enlarged skin flaps that do not reach the mouth. The slit-like eyes are positioned high on the head, and are followed by tiny spiracle
s. The mouth is short and wide, without furrows at the corners. There are 84 upper tooth rows and 97 lower tooth rows. Most of the small teeth have three cusps with the central cusp the longest; the teeth toward the jaw corners may also have 1–2 additional lateral cusplets. The upper teeth are exposed when the mouth is closed. 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 large and broad, with somewhat pointed tips and nearly straight trailing margins. The first dorsal fin
has a narrowly rounded apex and originates over the front half of the bases of the small pelvic fins. The second dorsal fin
is smaller and lower than the first, originating before the anal fin origin. The anal fin is much larger and deeper than the second dorsal fin. The caudal fin has a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. The body is densely covered by small, overlapping dermal denticles with a median ridge and a single cusp, though a few may be three-cusped. Adult sharks are variegated brown above, with 9–10 dark saddles over the body and tail, a dark blotch atop each pectoral fin, and a distinctive "V"-shaped dark marking at the tip of the caudal fin upper lobe; the underside is plain whitish. Juvenile sharks are light yellow above with dark transverse bars, some of which form hollow saddles, and a pair of narrow loops above the spiracles connected by a curved line.
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 at a depth of 480–700 m (1,574.8–2,296.6 ft) off northeastern Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
and possibly also nearby islands. This stout-bodied shark has a short, broad, and flattened head with a capacious mouth. Adults have a variegated brown coloration with 9–10 darker dorsal saddles and "V"-shaped blotch at the tip of the upper caudal fin lobe. Juveniles are yellow with narrow brown bars instead of saddles, and a distinctive marking between the 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 shaped like two loops connected by a line. Like other swellsharks, this species can inflate its body when threatened.
Taxonomy
In 1994, Commonwealth Scientific and Industrial Research OrganisationCommonwealth Scientific and Industrial Research Organisation
The Commonwealth Scientific and Industrial Research Organisation is the national government body for scientific research in Australia...
(CSIRO) chief researchers Peter Last and John Stevens recognized an undescribed 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...
n swellshark with a variegated color pattern, which they provisionally named Cephaloscyllium "sp. E". Later investigation revealed that "sp. E" in fact constituted two species: the speckled swellshark (C. speccum) and the flagtail swellshark, which was formally described in a 2008 CSIRO publication by Peter Last, Bernard Séret, and William White. In reference to its distinctive caudal fin marking, the shark was given the specific epithet signourum 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...
signum ("flag") and the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
oura ("tail"). The type specimen is a 74 cm (29.1 in) long female collected at the Lihou Reef and Cays, near Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
.
Distribution and habitat
The flagtail swellshark has been reported from Murray Island and Lihou Reef, off northeastern Queensland. Swellsharks found off New CaledoniaNew Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
, Vanuatu
Vanuatu
Vanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...
, and Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
may also be of this species as they closely resemble Australian specimens, but differ in some morphometric counts. This bottom-dwelling shark occurs at a depth of 480–700 m (1,574.8–2,296.6 ft).
Description
The flagtail swellshark reaches a length of at least 74 cm (29.1 in); if swellsharks from OceaniaOceania
Oceania is a region centered on the islands of the tropical Pacific Ocean. Conceptions of what constitutes Oceania range from the coral atolls and volcanic islands of the South Pacific to the entire insular region between Asia and the Americas, including Australasia and the Malay Archipelago...
prove to be conspecific with those from Australia, then this species can grow to over 1 m (3.3 ft) long. It has a fairly stout body and a short, very broad, and strongly flattened head. The snout is rounded, with nostril
Nostril
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 enlarged skin flaps that do not reach the mouth. The slit-like eyes are positioned 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 short and wide, without furrows at the corners. There are 84 upper tooth rows and 97 lower tooth rows. Most of the small teeth have three cusps with the central cusp the longest; the teeth toward the jaw corners may also have 1–2 additional lateral cusplets. The upper teeth are exposed when the mouth is closed. 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 large and broad, with somewhat pointed tips and nearly straight trailing margins. 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 narrowly rounded apex and originates over the front half of the bases of the small pelvic fins. The second 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...
is smaller and lower than the first, originating before the anal fin origin. The anal fin is much larger and deeper than the second dorsal fin. The caudal fin has a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. The body is densely covered by small, overlapping dermal denticles with a median ridge and a single cusp, though a few may be three-cusped. Adult sharks are variegated brown above, with 9–10 dark saddles over the body and tail, a dark blotch atop each pectoral fin, and a distinctive "V"-shaped dark marking at the tip of the caudal fin upper lobe; the underside is plain whitish. Juvenile sharks are light yellow above with dark transverse bars, some of which form hollow saddles, and a pair of narrow loops above the spiracles connected by a curved line.