''Pagetopsis'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Channichthyidae The crocodile icefish or white-blooded fish comprise a family (biology), family (Channichthyidae) of notothenioid fishes, fish found in the Southern Ocean around Antarctica. They are the only known vertebrates to lack hemoglobin in their blood as ...

, the

crocodile icefish The crocodile icefish or white-blooded fish comprise a family (biology), family (Channichthyidae) of notothenioid fishes, fish found in the Southern Ocean around Antarctica. They are the only known vertebrates to lack hemoglobin in their blood as ...

es. The species in this genus are found in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...

Taxonomy

''Pagetopsis'' was described as a genus in 1913 by the English

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Charles Tate Regan Charles Tate Regan (1 February 1878 – 12 January 1943) was a British ichthyology, ichthyologist, working mainly around the beginning of the 20th century. He did extensive work on fish classification schemes. Born in Sherborne, Dorset, he was ...

as a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus which had ''Champsocephalus macropterus'', which had been described by the Belgian-born British ichthyologist

George Albert Boulenger George Albert Boulenger (19 October 1858 – 23 November 1937) was a Belgian-British zoologist who described and gave scientific names to over 2,000 new animal species, chiefly fish, reptiles, and amphibians. Boulenger was also an active botani ...

in 1907, as its only species. The genus name is a combination of ''opsis'' with '' Pagetodes'', the name given by John Richardson in 1843 to an icefish frozen on the bow of HMS Terror which had been eaten by a cat before it could be preserved, Regan said that ''Pagetodes'' could not be used until that fish was rediscovered.

Species

There are currently two recognized species in this genus: * '' Pagetopsis macropterus'' (Boulenger, 1907) * '' Pagetopsis maculata'' Barsukov & Permitin, 1958

Characteristics

''Pagetopsis'' has a forward curving spine on the snout and a slightly protruding lower jaw. There are radiating ridge on the operculum ending in 3 or 4 spiny points, the other opercular bones lack spiny points. There are two

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

s, neither having any bony plates, although the middle lateral line is restricted to the

caudal peduncle Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

is fan shaped with a well developed membrane while the first

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

is large and tall and is contiguous with the second dorsal fin. The largest species is ''P. macropterus'' which attains a maximum total length of while the maximum total length of ''P. maculata'' is .

Distribution and habitat

''Pagetopsis'' Icefishes have a circumAntarctic distribution which extends as far north as the

South Shetland Islands The South Shetland Islands are a group of List of Antarctic and subantarctic islands, Antarctic islands located in the Drake Passage with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the n ...

and the

South Orkney Islands The South Orkney Islands are a group of List of Antarctic and sub-Antarctic islands, islands in the Southern Ocean, about north-east of the tip of the Antarctic Peninsula demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer o ...

fishes which are at depths down to .

References

{{Taxonbar, from=Q2051203 Channichthyidae Taxa named by Charles Tate Regan