The Australian Reticulate swellshark (Cephaloscyllium hiscosellum) is a little-known species of catshark, belonging to the family Scyliorhinidae. It is found off the coast of northwestern Australia at depths of between 951-1,378 feet. This is a newly described species that was once thought to be the same species as the Reticulated swellshark.
Family: Scyliorhinidae – Catsharks
Genus: Cephaloscyllium
Species: hiscosellum
Phylum– Chordata
Class– Chondrichthyles
Common Name– Ground Sharks
Family– Scyliorhinidae
Common Name– Catsharks
Genus– Cephaloscyllium
Species– hiscosellum
Status: IUCN Red List LEAST CONCERN
Average Size and Length: Male and female Australian Reticulate swellsharks are known to reach lengths of 46 cm/ 1.5 feet and 52 cm/ 1.7 feet.
Current Rare Mythical Sightings: The Australian Reticulate swellshark was once thought to be the same species as the Reticulated swellshark (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 Organization (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/1.5 feet long adult male caught west of Leander Point, Western Australia.
Teeth and Jaw: 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 near the symphysis of the upper jaw.
Head: They have a short, broad, wide flattened head. The head is between 8.9-13.1% of total length in height. The snout is broadly rounded, with the nostrils 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 spiracles. The prenarial length is between 4.5-5.2% of the total length. The preorbital snout length is 1.4-1.6 times the prenarial length. The snout-vent length is long, between 46.2-51.2% of the total length. The nostril is between 2.5-3.1% of the total length, in width. The eye-spiracle space is wide, between 0.8-1.2% of the total length.
Denticles: The dermal denticles are tiny and arrowhead-shaped, with a median ridge in males and both median and lateral ridges in females. The hatchlings seem to lack the specialized denticle used by other swellsharks to break out of the egg case.
Tail: The caudal fin is moderately large, with a distinct lower lobe and a strong ventral notch near the tip of the upper lobe.
Demographic, Distribution, Habitat, Environment and Range: The Australian Reticulate swellshark is found off the coast of northwestern Australia at depths of between 951-1,378 feet. They can be found on the upper continental slope off northwestern Australia, between Geraldton and Broome. They are considered subtropical bathypelagic.
Ram-Suction Index: More than likely they are high on the suction side of the index.
Aesthetic Identification: The Australian Reticulate swellshark has a stocky body. It has a striking dorsal color pattern of dark brown lines that trace a series of hollow saddles and narrow rings (some even have scattered yellow spots), on a light background. The ventral side is a uniform beige color. Like other swellsharks, this species can inflate itself when threatened. The fourth and fifth pairs of gill slits lie over the pectoral fin bases and are shorter than the first three. They are 2.6-3.1 in prepectoral length, 5.9-6.7 in prepelvic length. The pectoral fins are fairly small, narrow, and angular. The pectoral fin height is between 8.7-12.2% of the total length. The posterior margin length is between 7.4-11.4% of the total length. 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 trunk width is between 12.9-19.1% of the total length. The anal fin is relatively low, with a height of 2.8-3.7% of the total length. The anal-caudal space is between 5.4-6.5% of the total length. The precaudal length is between 76.4-79.2% of the total length. The interdorsal space is between 7.4-9.6% of the total length. The adult claspers are long, up to 9.3% of the total length, reaching the anal-fin origin.
Biology and Reproduction: They are oviparous. The egg cases are smooth, light yellow flask-shaped or purse shaped, which have a flanged margin and horns at the corners that support long, coiled tendrils. Males mature sexually between a length of 39–46 cm/1.3-1.5 feet. The vertebral centra count is 100-108.
Behavioral Traits, Sensing and Intelligence: Like other members of its genus, they have the ability to inflate their stomach with water (or air n land) in an effort to deter potential predators.
Speed: They are more than likely sluggish swimmers.
Australian Reticulate Swellshark Future and Conservation: They are currently of least concern.
Australian Reticulate Swellshark Recorded Attacks on Humans: Not a threat to humans.