''Acanthurus reversus'' is a species of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Acanthuridae Acanthuridae are the family of 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 brightly colored and popular in aq ...

, which includes the surgeonfishes, unicornfishes and tangs. This fish is endemic to

French Polynesia )Territorial motto: ( en, "Great Tahiti of the Golden Haze") , anthem = , song_type = Regional anthem , song = " Ia Ora 'O Tahiti Nui" , image_map = French Polynesia on the globe (French Polynesia centered).svg , map_alt = Location of Frenc ...

Taxonomy

''Acanthurus reversus'' was first formally described in 1999 by the American

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, 33,400 species of fish had been described as of Octobe ...

John Ernest Randall John Ernest "Jack" Randall (May 22, 1924 – April 26, 2020) was an American ichthyologist and a leading authority on coral reef fishes. Randall described over 800 species and authored 11 books and over 900 scientific papers and popular articles. ...

and

John L. Earle John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second E ...

with its type locality given as off a point at the southern end of Marquisienne Bay, Nuku Hiva in the Marquesas Islands. This species is closely related to the widespread orangeband surgeonfish ('' A. olivaceus''), and together these taxa form a species complex within the

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 ...

'' Acanthurus''. The genus ''Acanthurus'' is one of two genera in the tribe Acanthurini which is one of three tribes in 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 subfamily botanical names with "-oideae", and zoologi ...

Acanthurinae ''Acanthurinae'' is a subfamily of fish belonging to the family Acanthuridae, including 55 species in four genera. Description Among the species of the genera ''Acanthurus'' and ''Zebrasoma'' there are small anatomical differences: the fir ...

which is one of two subfamilies in the family Acanthuridae.

Etymology

''Acanthurus reversus'' was given the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''reversus'', this means “reversed” and refers to the reversed pattern if colours on 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 ...

of this species in comparison to the closely related ''A. olivaceus''.

Description

''Acanthurus reversus'' has its

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 ...

supported by 9 spines and 24 or 25 soft rays while the

anal 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 supported by 3 spines and 23 or 24 soft rays. Its overall colour is brown, although the posterior may be clearly paler than the anterior. There is an elongated orange spot running from the upper end of the gill slit With its, posterior have being surrounded by a blue band that reaches beyond the

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 ...

. There is an indistinct orange line at the base of both the dorsal and anal fins and the soft-rayed part of the dorsal fin has 3 dark horizontal bands while the anal fin has a blue margin. The caudal fin is light yellow with a wide black band to its rear, this narrows as it reaches the filamentous part of the lobes. Juveniles are yellow and have blue margins on their dorsal and anal fins. The maximum published total length of the Marquesas surgeonfish is .

Distribution and habitat

''Acanthurus reversus'' Is endemic to the Marquesas Islands in French Polynesia. There is a record of an individual from Takaroa Atoll in the

Tuamotu Archipelago The Tuamotu Archipelago or the Tuamotu Islands (french: Îles Tuamotu, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extendin ...

but this is thought to have referred to a

vagrant Vagrancy is the condition of homelessness without regular employment or income. Vagrants (also known as bums, vagabonds, rogues, tramps or drifters) usually live in poverty and support themselves by begging, scavenging, petty theft, temporar ...

. The Marquesas surgeonfish is found singly or in small groups on inshore reefs at depths between .

References

reversus Fish described in 1999 Taxa named by John Ernest Randall {{Acanthuridae-stub