''Acanthurus'' 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 ...

Acanthuridae Acanthuridae are a family of ray-finned fish which includes surgeonfishes, tangs, and unicornfishes. The family includes about 86 extant species of marine fish living in tropical seas, usually around coral reefs. Many of the species are brigh ...

, which includes the surgeonfishes, unicornfishes and tangs, found in the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, Indian and

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. They are found in tropical oceans, especially near

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...

s, with most

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

but a few are found in the Atlantic Ocean. As other members of the family, they have a pair of spines, one on either side of the base of the

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

which are dangerously sharp.

Taxonomy

''Acanthurus'' was first proposed as a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of ''

Chaetodon ''Chaetodon'' is a tropical fish genus in the family (biology), family Chaetodontidae. Like their relatives, they are known as "butterflyfish". This genus is by far the largest among the Chaetodontidae, with about 90 living species included here, ...

'' in 1775 by the Swedish-speaking Finnish

explorer Exploration is the process of exploring, an activity which has some Expectation (epistemic), expectation of Discovery (observation), discovery. Organised exploration is largely a human activity, but exploratory activity is common to most organis ...

, orientalist and

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

Peter Forsskål Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl (11 January 1732 – 11 July 1763) was a Sweden, Swedish exploration, explorer, oriental studies, orientalist, natural history, naturalist, and ...

, although he recognised that it was probably different from ''Chaetodon'' even at the family level. In 1856 Desmarest designated ''Teuthis hepatus'', which had been described from a

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

now known to have been collected at Ambon Island in the Moluccas (other erroneous type localities were named) in 1758 by Linnaeus, as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the genus. ''T. hepatus'' is a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of '' Paracanthurus hepatus'' and this would make ''Paracanthurus'' synonymous with ''Acanthurus''. An alternative would be to use the name ''Harpurus'' proposed as a

monospecific genus 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 "unispe ...

in 1788 by

Johann Reinhold Forster Johann Reinhold Forster (; 22 October 1729 – 9 December 1798) was a German Reformed pastor and naturalist. Born in Tczew, Dirschau, Pomeranian Voivodeship (1466–1772), Pomeranian Voivodeship, Polish–Lithuanian Commonwealth (now Tczew, Po ...

when he described ''Harpurus fasciatus'', a synonym of ''Acanthurus triostegus''. It has been proposed that the International Commission on Zoological Nomenclature should be petitioned to stabilise the genera ''Acanthurus'' and ''Paracanthurus''. In 2014 it was proposed that the type species of ''Acanthurus'' should be '' Chaetodon sohal'', which had also been described by Forsskål in 1775 as a member of the subgenus alongside '' C. bifasciatus'', '' C. nigrofuscus'' and '' C. unicornis'', and had been designated as the type species by

Jordan Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...

and Evermann in 1917.

Paraphyly

It has been proposed that the genus ''

Ctenochaetus ''Ctenochaetus'', or bristletooth tangs, is a genus of marine ray-finned fish belonging to the family Acanthuridae, which includes the surgeonfishes, unicornfishes and tangs. These fishes are found in the Indo-Pacific region. They have many, smal ...

'' should be merged with ''Acanthurus'', as ''Acanthurus'' is currently

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

. All ''Ctenochaetus'' species are nested within ''Acanthurus'', while '' A. nubilis'' and '' A. pyroferus'' are furthermore nested within ''Ctenochaetus''. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' recognises these two genera as valid and classifies them as the two genera in the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Acanthurini Acanthurini is a tribe of marine ray-finned fishes belonging to the family Acanthuridae and it is one of three tribes in the subfamily Acanthurinae. Taxonomy Acanthurini was first proposed as a taxon in 1839 by the French naturalist Charles Lucie ...

of the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Acanthurinae ''Acanthurinae'' is a subfamily of marine ray-finned fishes belonging to the Family (biology), family Acanthuridae, found in the Indo-Pacific and the tropical Atlantic. These fishes commonly have the English names surgeonfishes or tangs. Taxono ...

within the family Acanthuridae.

Etymology

''Acanthurus'' is a combination of the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

words ἄκανθα (''ákantha''), meaning "spine", and οὐρά (''ourá''), meaning "tail", a reference to the scalpel like bony plates on the caudal peduncle, these also give rise to the vernacular English names surgeonfish and doctorfish.

Species

There are currently 41 recognized species in this genus: * '' Acanthurus achilles'' G. Shaw, 1803 (Achilles surgeonfish) * '' Acanthurus albimento'' K. E. Carpenter, J. T. Williams & M. D. Santos, 2017 (White-chin surgeonfish)Carpenter, K.E., Williams, J.T. & Santos, M.D. (2017)
''Acanthurus albimento'', a new species of surgeonfish (Acanthuriformes: Acanthuridae) from northeastern Luzon, Philippines, with comments on zoogeography.
''Journal of the Ocean Science Foundation, 25: 33–46.'' * '' Acanthurus albipectoralis'' G. R. Allen & Ayling, 1987 (White-fin surgeonfish) * '' Acanthurus auranticavus'' J. E. Randall, 1956 (Orange-socket surgeonfish) * '' Acanthurus bahianus'' Castelnau, 1855 (Barber surgeonfish) * '' Acanthurus bariene''

Lesson A lesson or class is a structured period of time where learning is intended to occur. It involves one or more students (also called pupils or learners in some circumstances) being taught by a teacher or instructor. A lesson may be either one ...

, 1831 (Black-spot surgeonfish) * '' Acanthurus blochii''

Valenciennes Valenciennes (, also , , ; ; or ; ) is a communes of France, commune in the Nord (French department), Nord Departments of France, department, Hauts-de-France, France. It lies on the Scheldt () river. Although the city and region experienced ...

, 1835 (Ring-tail surgeonfish) * '' Acanthurus chirurgus'' (

Bloch Bloch is a surname of German origin. Notable people with this surname include: A *Adele Bloch-Bauer (1881–1925), Austrian entrepreneur *Albert Bloch (1882–1961), American painter *Alexandre Bloch (1857–1919), French painter *Alfred Bloch ( ...

, 1787) (Doctorfish tang) * ''Acanthurus chronixis'' J. E. Randall, 1960 (Chronixis surgeonfish) * ''Acanthurus coeruleus'' Bloch & Johann Gottlob Theaenus Schneider, J. G. Schneider, 1801 (Atlantic blue tang) * ''Acanthurus dussumieri'' Valenciennes, 1835 (Eye-stripe surgeonfish) * ''Acanthurus fowleri'' Lieven Ferdinand de Beaufort, de Beaufort, 1951 (Fowler's surgeonfish) * ''Acanthurus gahhm'' (Peter Forsskål, Forsskål, 1775) (Black surgeonfish) * ''Acanthurus grammoptilus'' John Richardson (naturalist), J. Richardson, 1843 (Fine-lined surgeonfish) * ''Acanthurus guttatus'' Johann Reinhold Forster, J. R. Forster, 1801 (White-spotted surgeonfish) * ''Acanthurus japonicus'' (Peter Yulevich Schmidt, P. J. Schmidt, 1931) (Japan surgeonfish) * ''Acanthurus leucocheilus'' Albert William Christian Theodore Herre, Herre, 1927 (Pale-lipped surgeonfish) * ''Acanthurus leucopareius'' (Oliver Peebles Jenkins, O. P. Jenkins, 1903) (White-bar surgeonfish) * ''Acanthurus leucosternon'' Edward Turner Bennett, E. T. Bennett, 1833 (Powder-blue surgeonfish) * ''Acanthurus lineatus'' (Carl Linnaeus, Linnaeus, 10th edition of Systema Naturae, 1758) (Lined surgeonfish) * ''Acanthurus maculiceps'' (Christoph Gustav Ernst Ahl, C. G. E. Ahl, 1923) (White-freckled surgeonfish) * ''Acanthurus mata'' (Georges Cuvier, G. Cuvier, 1829) (Elongate surgeonfish) * ''Acanthurus monroviae'' Franz Steindachner, Steindachner, 1876 (Monrovia surgeonfish) * ''Acanthurus nigricans'' (Linnaeus, 10th edition of Systema Naturae, 1758) (White-cheek surgeonfish) * ''Acanthurus nigricauda'' Paul Georg Egmont Duncker, Duncker & Erna Mohr, Mohr (:de:Erna Mohr, de), 1929 (Epaulette surgeonfish) * ''Acanthurus nigrofuscus'' (Forsskål, 1775) (Brown surgeonfish) * ''Acanthurus nigroris'' Valenciennes, 1835 (Blue-lined surgeonfish) * ''Acanthurus nigros'' Albert Karl Ludwig Gotthilf Günther, Günther, 1861 (Grey-head surgeonfish)Randall, J.E., DiBattista, J.D. & Wilcox, C. (2011): ''Acanthurus nigros'' Günther, a Valid Species of Surgeonfish, Distinct from the Hawaiian ''A. nigroris'' Valenciennes. ''Pacific Science, 65 (2): 265–275.'' * ''Acanthurus nubilus'' (Henry Weed Fowler, Fowler & Barton Appler Bean, B. A. Bean, 1929) (Pin-striped surgeonfish) * ''Acanthurus olivaceus'' Bloch & J. G. Schneider, 1801 (Orange-spot surgeonfish) * ''Acanthurus polyzona'' (Pieter Bleeker, Bleeker, 1868) (Black-barred surgeonfish) * ''Acanthurus pyroferus'' Friedrich Heinrich von Kittlitz, Kittlitz, 1834 (Chocolate surgeonfish) * ''Acanthurus randalli'' John Carmon Briggs, J. C. Briggs & David Keller Caldwell, D. K. Caldwell, 1957 * ''Acanthurus reversus'' J. E. Randall & John L. Earle, Earle, 1999 * ''Acanthurus sohal'' (Forsskål, 1775) (Sohal surgeonfish) * ''Acanthurus tennentii'' Günther, 1861 (Double-band surgeonfish) * ''Acanthurus thompsoni'' (Fowler, 1923) (Thompson's surgeonfish) * ''Acanthurus tractus'' Felipe Poey y Aloy, F. Poey, 1860 (Ocean surgeonfish)Bernal, M.A. & Rocha, L.A. (2011)
''Acanthurus tractus'' Poey, 1860, a valid western Atlantic species of surgeonfish (Teleostei, Acanthuridae), distinct from ''Acanthurus bahianus'' Castelnau, 1855.
''Zootaxa, 2905: 63–68.'' * ''Acanthurus triostegus'' (Linnaeus, 10th edition of Systema Naturae, 1758) (Convict surgeonfish) * ''Acanthurus tristis'' J. E. Randall, 1993 (Indian Ocean mimic surgeonfish) * ''Acanthurus xanthopterus'' Valenciennes, 1835 (Yellow-fin surgeonfish)

Characteristics

''Acanthurus'' surgeonfishes have disc shaped, highly laterally compressed bodies with a steep dorsal profile to the head. They have a small mouth positioned low on the head and the fish can protrude the jaws. The 8 to 28 teeth in the jaws are fixed and have flattened, serrated tips. There are typically 11 spines in the dorsal fin. There is a single spine on each side of the caudal peduncle and these can be pressed down into a groove. The

yellowfin surgeonfish (''A. xanthopterus'') is the largest species with a maximum published total length of while the smallest is the black-barred surgeonfish (''Acanthurus polyzona, A. polyzona'') with a maximum published total length of .

Distribution

''Acanthrus'' surgeonfishes are distributed around the world in tropical waters.

References

{{Authority control Acanthurus, Acanthurini Marine fish genera Taxa named by Peter Forsskål