Naso (fish)

{{Short description|Genus of fishes}} {{Automatic taxobox | fossil_range = Eocene to present<ref>{{Cite journal | last = Sepkoski | first = Jack | author-link = | title = A compendium of fossil marine animal genera | journal = Bulletins of American Paleontology | volume = 364 | issue = | pages = 560 | year = 2002 | url = http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=611&rank=class | doi = | id = | access-date = 2008-01-08 }}</ref> | image = Bluespine Unicornfish, Emily Bay, Kingston 2899, Norfolk Island imported from iNaturalist photo 173453689 (cropped).jpg | image_caption = Bluespine unicornfish (''N. unicornis'') | taxon = Naso | parent_authority = Fowler & Bean, 1929 | authority = Lacépède, 1801 | type_species = ''Acanthurus fronticornis'' | type_species_authority = Lacepède, 1801 | synonyms = {{collapsible list|bullets = true|title=<small>List</small> | ''Atulonotus'' <br>{{small|J. L. B. Smith, 1955}} | ''Axinurus'' <br>{{small|Cuvier, 1829}} | ''Callicanthus'' <br>{{small|Swainson 1839}} | ''Cyphomycter'' <br>{{small|Fowler & Bean, 1929}} | ''Keris'' <br>{{small|Valenciennes, 1835}} | ''Monoceros'' <br>{{small|Bloch & Schneider, 1801}} | ''Nasonus'' <br>{{small|Rafinesque, 1815}} | ''Priodon'' <br>{{small|Quoy & Gaimard, 1825}} | ''Priodontichthys'' <br>{{small|Bonaparte, 1831}} | ''Prionolepis'' <br>{{small|J. L. B. Smith, 1931}} | ''Rhinodactylus'' <br>{{small|J. L. B. Smith, 1957}} }} | synonyms_ref = <ref name = CofF>{{Cof family|family=Acanthuridae|access-date=10 July 2023}}</ref> | subdivision_ranks = Species | subdivision = 20., see text }}

'''''Naso''''' is a genus of marine ray-finned fishes belonging to the family, Acanthuridae, the unicornfishes, surgeonfishes and tangs. The fishes in this genus are known commonly as '''unicornfishes''' because of the "rostral protuberance", a hornlike extension of the forehead present in some species.<ref name = Dayton>{{cite journal |author=Dayton, C. |year=2001 |url=https://link.springer.com/article/10.1007/s002270100628#page-1 |title=Genetic evolution among selected members of the genus ''Naso'' (Nasinae), "unicornfishes" from Guam |journal=Marine Biology |volume =139 |issue=4 |pages=771–76|doi=10.1007/s002270100628 |bibcode=2001MarBi.139..771D |url-access=subscription }}</ref>

Unicorn fish are popular with spearfishermen<ref>{{Cite web |url=http://guam.stripes.com/news/fishing-tip-spear-guam |title=Fishing at the tip of the spear in Guam |access-date=2018-09-06 |archive-date=2018-12-31 |archive-url=https://web.archive.org/web/20181231133618/http://guam.stripes.com/news/fishing-tip-spear-guam |url-status=dead }}</ref> and may be cooked by grilling them whole.<ref name="Delishably">{{cite web |url=https://delishably.com/meat-dishes/Unicorn-Fish-The-Weird-But-Delicious-Fish |title=Unicorn Fish the weird but delicious fish |date=5 November 2022 |access-date=10 July 2023 |publisher=The Arena Media Brands, LLC}}</ref> Unicornfish primarily live around coral reefs and eat mostly algae.<ref name="reefapp">{{cite encyclopedia |url=https://reefapp.net/en/lex/category/acanthuridae#Naso |title=Acanthuridae (Surgeonfishes/Tangs) |encyclopedia=Reef App encyclopaedia for marine animals |access-date=10 July 2023 |publisher=Kasper Hareskov Tygesen}}</ref>

This genus is distributed across the Indo-Pacific from Africa to Hawaii.<ref name = Borden>{{cite journal| author=Borden, W. C. |year=1998 |doi=10.2307/1447705 |title=Phylogeny of the unicornfishes (''Naso'', Acanthuridae) based on soft anatomy |journal=Copeia |volume=1998 |issue=1 |pages=104–113|jstor=1447705 }}</ref>

==Taxonomy== ''Naso'' was first proposed as a genus in 1801 by Bernard Germain de Lacépède when he described ''Naso fronticornis'' as a new species from Jeddah and Mauritius.<ref name = CofF/> Lacépède's name was an unnecessary replacement of ''Chaetodon unicornis'' described by Peter Forsskål in 1775 from Jeddah.<ref name = CofF2>{{Cof genus|genus=Naso|access-date=11 July 2023}}</ref> In 1917 David Starr Jordan designated ''Naso fronticornis'' as the type species of the genus ''Naso''.<ref name = CofF/> ''Naso'' is the only genus in the monogeneric subfamily Nasinae, proposed by Henry Weed Fowler and Barton Appler Bean in 1929<ref name = VDLEF>{{cite journal | author1 = Richard van der Laan | author2 = William N. Eschmeyer | author3 = Ronald Fricke | name-list-style = amp |year=2014 | title = Family-group names of recent fishes | url = https://biotaxa.org/Zootaxa/article/view/zootaxa.3882.1.1/10480 | journal = Zootaxa | volume = 3882 | issue = 2 | pages = 1–230| doi = 10.11646/zootaxa.3882.1.1 | pmid = 25543675 | doi-access = free }}</ref> within the family Acanthuridae.<ref name = Nelson5>{{cite book |title=Fishes of the World |edition=5th |author1=J. S. Nelson |author2=T. C. Grande |author3=M. V. H. Wilson |year=2016 |pages=497–502 |publisher=Wiley |isbn=978-1-118-34233-6 |url=https://sites.google.com/site/fotw5th/ |archive-date=2019-04-08 |access-date=2023-07-11 |archive-url=https://web.archive.org/web/20190408194051/https://sites.google.com/site/fotw5th/ |url-status=dead }}</ref>

=== Etymology === ''Naso'' means "nose" referring to the fleshy protuberance on the forehead of ''N. fronticornis'' (=''unicornis''). The subgenus ''Axinurus'' comes from ''axino'' and ''oura'', meaning axe-tail, potentially referring to the presence of a single tail spine on each side as opposed to two in the subgenus ''Naso''.<ref name="ETYFish" />

==Distribution== ''Naso'' unicornfishes are found in the Indo-Pacific region from the eastern coast of Africa to the Galápagos Islands.<ref name="WIOF" /> ==Characteristics== ''Naso'' unicornfishes have a pointed snout and a rhomboidal or oval shaped body, with some species possessing a long protuberance on the forehead, typically present in both males and females. The caudal peduncle is slender and there are 1 or 2 anteriorly directed sharp, blade-shaped spines mounted on bony plates on each side. The caudal fin varies from slightly rounded to highly emarginate. In some species there are long filaments at the tips of the lobes of the caudal fin, sometimes restricted to males. The dorsal fins of these fishes are supported by between 4 and 7 spines and between 24 and 31 soft rays while the anal fin contains 2 spines and 23 to 30 soft rays. There is a single spine and 3 soft rays in the pelvic fins and between 16 and 19 soft rays in the pectoral fins.<ref name="WIOF">{{cite book |author=John E. Randall |chapter=Family Acanthuridae |pages=219–244 |title=Coastal Fishes of the Western Indian Ocean |volume=5 |editor1=Phillip C Heemstra |editor2=Elaine Heemstra |editor3=David A Ebert |editor4=Wouter Holleman |editor5=John E Randall |year=2022 |isbn=978-1-990951-32-9 |publisher=South African Institute for Aquatic Biodiversity |url=https://saiab.ac.za/wp-content/uploads/2022/11/1._wiof_volume_5_text.pdf}}</ref>

The species in the genus ''Naso'' vary in size from a maximum published standard length of {{cvt|30|cm}} in the slender unicorn (''N. minor'') to a maximum published total length of {{cvt|100|cm}} in the whitemargin unicornfish (''N. annulatus'').<ref name="Fishbase" />

There are two subgenera which are distinguished by the number of keels on the caudal peduncle with the nominate subgenus, ''Naso'' having a pair on each side of the peduncle while the subgenus ''Axinurus'' has a single keel on each side.<ref name="Randall1994">{{cite journal |author=John E. Randall |year=1994 |title=Unicornfishes of the Subgenus ''Axinurus'' (Perciformes: Acanthuridae: ''Naso''), with Description of a New Species |journal=Copeia |volume=1994 |issue=1 |pages=116–124 |doi=10.2307/1446677|jstor=1446677 }}</ref>

==Biology== {{Multiple image | image1 = Orangespine Unicornfish - Naso lituratus (cropped).jpg | image2 = Naso lituratus Gratwicke.jpg | total_width = 250 | footer = ''N. elegans'' (top) and ''N. lituratus'' (bottom) are closely related, and once considered the same species. | direction = vertical }} ''Naso'' unicornfishes differ from other acanthurids in that they eat zooplankton rather than grazing on algae or detritus and that they tend to live at greater ranges of depth.<ref name="WIOF" />

=== Cephalic horn function === Some species exhibit a large horn on the forehead. It is uncertain what the purpose of this horn is. One explanation postulates that is a result of sexual selection, ie serving a purpose in competition and communication, which may be within or between the sexes, or both. Alternatively, it has been hypothesized that they instead perform a hydrodynamic function, assisting the species that exhibit them with precision movements. This is because both fast swimming "scombriform" shaped species and small species typically lack the horn, while it is only the large relatively slow-swimming species which display the horn.<ref name=":0">{{Cite journal |last=DeMartini |first=Edward E. |date=July 2016 |title=Sexual Dimorphisms in the Bluespine Unicornfish, Naso unicornis (Acanthuridae): External Metrics for Movement Ecology and Life History |url=http://www.bioone.org/doi/10.1643/CE-15-270 |journal=Copeia |language=en |volume=104 |issue=2 |pages=498–505 |doi=10.1643/CE-15-270 |issn=0045-8511|url-access=subscription }}</ref>

Molecular phylogenetics show that horns independently evolved multiple times within the genus, and only ever evolved in benthic feeding species. Similarly, benthic-feeding also evolved multiple times independently. In addition, pelagic feeding and the fast-swimming "scombriform" body shape appear to be plesiomorphic traits. This is because the basalmost species in ''Naso'' are the pelagic feeding "scombriform" species in the subgenus ''Axinurus'', and because every other acanthurid genus comprises predominantly benthic feeders.<ref>{{Cite journal |last1=Klanten |first1=Selma O. |last2=Herwerden |first2=Lynne van |last3=Choat |first3=J.Howard |last4=Blair |first4=David |date=July 2004 |title=Patterns of lineage diversification in the genus Naso (Acanthuridae) |url=https://linkinghub.elsevier.com/retrieve/pii/S1055790303004202 |journal=Molecular Phylogenetics and Evolution |language=en |volume=32 |issue=1 |pages=221–235 |doi=10.1016/j.ympev.2003.11.008|bibcode=2004MolPE..32..221K |url-access=subscription }}</ref>

In some species, both males and females display such a horn. In at least some species where this is the case, such as the bluespine unicornfish, the horn is slightly sexually dimorphic, being slightly larger in males.<ref name=":0" /> In other species, such as the humpback unicornfish, the horn is almost completely absent in females.<ref name="WIOF"/>

==Species== ''Naso'' is divided into two subgenera<ref name = ETYFish>{{cite web | url = https://etyfish.org/acanthuriformes2/ | title = Order Acanthuriformes (part 2): Families Ephippidae, Leiognathidae, Scatophagidae, Antigoniidae, Siganidae, Caproidae, Luvaridae, Zanclidae and Acanthuridae | work = The ETYFish Project Fish Name Etymology Database | editor1= Christopher Scharpf | editor2 = Kenneth J. Lazara | name-list-style = amp |date = 12 January 2021 | access-date = 10 July 2023 | publisher = Christopher Scharpf and Kenneth J. Lazara}}</ref> and 20 species are classified within it:<ref name = Fishbase>{{FishBase genus |genus=Naso |month=February |year=2023}}</ref> {| class="wikitable" |+Subgenus ''Naso'' <small>Lacepède, 1801</small> !Species !Common name !Image |- |''Naso annulatus'' <small>(Quoy & Gaimard, 1825)</small> |whitemargin unicornfish |frameless |- |''Naso brachycentron'' <small>(Valenciennes, 1835)</small> |humpback unicornfish |frameless |- |''Naso brevirostris'' <small>(G. Cuvier, 1829)</small> |spotted unicornfish |frameless |- |''Naso caesius'' <small>J. E. Randall & Bell, 1992</small> |gray unicornfish |frameless |- |''Naso elegans'' <small>(Rüppell, 1829)</small> |elegant unicornfish |frameless |- |''Naso fageni'' <small>Morrow, 1954</small> |horseface unicornfish |frameless |- |''Naso hexacanthus'' <small>(Bleeker, 1855)</small> |sleek unicornfish |frameless |- |''Naso lituratus'' <small>(J. R. Forster, 1801)</small> |orangespine unicornfish |frameless |- |''Naso lopezi'' <small>Herre, 1927</small> |elongated unicornfish |frameless |- |''Naso maculatus'' <small>J. E. Randall & Struhsaker, 1981</small> |spotted unicornfish | |- |''Naso mcdadei'' <small>J. W. Johnson, 2002</small> |squarenose unicornfish |frameless |- |''Naso reticulatus'' <small>J. E. Randall, 2001</small> |reticulated unicornfish |frameless |- |''Naso tergus'' <small>H. C. Ho, K. N. Shen & C. W. Chang, 2011</small> |Taiwanese unicornfish | |- |''Naso tonganus'' <small>(Valenciennes, 1835)</small> |bulbnose unicornfish |frameless |- |''Naso tuberosus'' <small>Lacépède, 1801</small> |humpnose unicornfish |frameless |- |''Naso unicornis'' <small>(Forsskål, 1775)</small> |bluespine unicornfish |frameless |- |''Naso vlamingii'' <small>(Valenciennes, 1835)</small> |bignose unicornfish |frameless |} {| class="wikitable" |+Subgenus ''Axinurus'' <small>Cuvier 1829</small> !Species !Common name !Image |- |''Naso caeruleacauda'' <small>J. E. Randall, 1994</small> |blue unicornfish |frameless |- |''Naso minor'' <small>(J. L. B. Smith, 1966)</small> |slender unicornfish |frameless |- |''Naso thynnoides'' <small>(G. Cuvier, 1829)</small> |oneknife unicornfish |frameless |}

==References== {{Reflist}}

{{Taxonbar|from=Q1515467}} {{Authority control}}

Category:Naso (fish) Category:Acanthuridae Category:Extant Eocene first appearances Category:Marine fish genera Category:Taxa named by Bernard Germain de Lacépède