''Irolita'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

softnose skate Arhynchobatidae is a family of skates and is commonly known as the softnose skates. It belongs to the order Rajiformes in the superorder Batoidea of rays. At least 104 species have been described, in 13 genera. Softnose skates have at times been ...

s in the family

Arhynchobatidae Arhynchobatidae is a family of skates and is commonly known as the softnose skates. It belongs to the order Rajiformes in the superorder Batoidea of rays. At least 104 species have been described, in 13 genera. Softnose skates have at times been ...

, commonly known as round skates. There are two species, both

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 Australia, found over soft bottoms on the outer

continental shelves 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 A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

s, at depths of 50–200 m for the southern round skate and 142–209 m for the western round skate. The distributions of the two species do not overlap.

Species

* ''Irolita waitii''

McCulloch McCulloch is a Scottish surnames, Scottish surname. It's a variation of the Northern Irish surname McCullough. It's commonly found in Galloway. Notable people with the surname include: *Alan McCulloch (politician), New Zealand politician *Alan ...

, 1911 * ''Irolita westraliensis''

Last A last is a mechanical form shaped like a human foot. It is used by shoemakers and cordwainers in the manufacture and repair of shoes. Lasts typically come in pairs and have been made from various materials, including hardwoods, cast iron, and ...

& Gledhill, 2008

Description

Both species are unique amongst Australian skates in having a smooth, almost circular heart-shaped

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 ...

disc. The head is short, with a small fleshy process at the tip of the

snout A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw. In many animals, the structure is called a muzzle, rostrum, or proboscis. The wet furless surface around the nostrils of the nose of many mammals is c ...

and large

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 behind the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

s. The nasal flaps are merged into a well-developed, bilobed nasal curtain forward of the

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

. The

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s are slightly arched with the upper teeth exposed. The teeth are

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

; those of adult males are spear-shaped with long, sharp cusps, while those of females and juveniles are plate-like with short posterior cusps. 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 ...

s are deeply incised, with the anterior lobe moderately long and slender and the posterior lobe broadly rounded. The tail is narrow, tapering gradually to a very slender tip and bearing two small

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 ...

s near the end. 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 reduced to minute lobes. Males have alar thorns near the pectoral fin tips and the tail is covered with irregular rows of small recurved thorns.

References

{{Taxonbar, from=Q5025192 Rajidae Ray genera Taxa named by Gilbert Percy Whitley