| Australian reticulate swellshark | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Scyliorhinidae |
| Genus: | Cephaloscyllium |
| Species: | C. hiscosellum |
| Binomial name | |
| Cephaloscyllium hiscosellum W. T. White &Ebert, 2008 | |
TheAustralian reticulate swellshark (Cephaloscyllium hiscosellum) is a little-knownspecies of catshark in thefamilyScyliorhinidae. It is found off the coast of northwesternAustralia at depths of 290–420 m (950–1,380 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. Its reproduction isoviparous.[2]
Once thought to be the same species as thereticulated swellshark (C. fasciatum) ofVietnam andHainan, the Australian reticulate swellshark was described as a separate species by William White and David Ebert in a 2008Commonwealth Scientific and Industrial Research Organisation (CSIRO) publication.[3] Itsspecific epithethiscosellum is derived from theLatinhisco meaning "open", andsella meaning "saddle", referring to its distinctive color pattern. Thetype specimen is a 46 cm (18 in) long adult male caught west of Leander Point,Western Australia.[3]
Male and female Australian reticulate swellsharks are known to attain lengths of 46 cm (18 in) and 52 cm (20 in) respectively. This species has a stocky body and a short, broad, and strongly flattened head. The snout is broadly rounded, with thenostrils 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 tinyspiracles. 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 ofgill slits lie over thepectoral fin bases and are shorter than the first three.[3]
The pectoral fins are fairly small, narrow, and angular. Thepelvic fins are small, with long, elongateclaspers in males. The firstdorsal 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 angularanal fin is substantially larger than, and placed slightly behind, the second dorsal fin. Thecaudal fin is moderately large, with a distinct lower lobe and a strong ventral notch near the tip of the upper lobe. Thedermal 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.[3][4]
The range of the Australian reticulate swellshark is limited to the uppercontinental slope off northwestern Australia, betweenGeraldton andBroome. It occurs at a depth of 290–420 m (950–1,380 ft).[4]
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.[4] The eggs of thisoviparous species are contained in smooth, light yellow flask-shapedcapsules, which have a flanged margin and horns at the corners that support long, coiled tendrils.[3] The hatchlings seem to lack the specialized denticle used by other swellsharks to break out of the egg case.[4] Malesmature sexually between a length of 39–46 cm (15–18 in).[3]
TheInternational Union for Conservation of Nature (IUCN) has identified minimal threats the Australian reticulate swellshark, and thus classifying it as "data deficient."[1]
