Rivulus

{{Short description|Genus of fishes}} {{Automatic taxobox | image = Rivulus cylindraceus.jpg | image_caption = ''Rivulus cylindraceus'' (male) | taxon = Rivulus | authority = Poey, 1860 | type_species = ''Rivulus cylindraceus'' | type_species_authority = Poey, 1860 }}

'''''Rivulus''''' is a genus of small freshwater fish in the Cyprinodontiformes family Rivulidae. It was traditionally considered to be the largest genus in its family; however, the genus's size is currently in dispute. Wilson J. E. Costa split this genus into several new genera (including ''Anablepsoides, Atlantirivulus, Cynodonichthys'', ''Kryptolebias'', ''Laimosemion'' and ''Melanorivulus'') in 2004 and 2011, leaving only a few Greater Antillean species in ''Rivulus'' itself.<ref name=Costa2011>{{cite journal | author = Costa W.J.E.M. | year = 2011 | title = Phylogenetic position and taxonomic status of ''Anablepsoides, Atlantirivulus, Cynodonichthys, Laimosemion'' and ''Melanorivulus'' (Cyprinodontiformes: Rivulidae) | journal = Ichthyological Exploration of Freshwaters | volume = 22 | issue = 3| pages = 233–249 }}</ref> Despite being moved to other genera, some of the species retain the common name "rivulus", like the well-known mangrove rivulus (''Kryptolebias marmoratus''). Shortly after the review by Costa, another review authored by J.H. Huber refuted the split, moving the proposed genera back in ''Rivulus'' and again making the genus the largest in the family Aplocheilidae.<ref name=Huber2012>Huber, J.H., 2012. Reappraisal of the Phylogeny of Rivulus and its Allied Focused on External Characters. Killi-Data Series 2012: 9-25.</ref>

If the split is recognized, the genus ''Rivulus'' only includes three non-annual killifish species from western Cuba (including Isla de la Juventud) and Hispaniola where they inhabit streams, rivers and lagoons from the highlands to the coast.<ref name=PonceDeLeon2014>{{Cite journal |doi = 10.1016/j.ympev.2014.07.007|title = Phylogeography of Cuban Rivulus: Evidence for allopatric speciation and secondary dispersal across a marine barrier|year = 2014|last1 = Ponce De León|first1 = José Luis|last2 = León|first2 = Gunnary|last3 = Rodríguez|first3 = Rodet|last4 = Metcalfe|first4 = Cushla J.|last5 = Hernández|first5 = Damir|last6 = Casane|first6 = Didier|last7 = García-Machado|first7 = Erik|journal = Molecular Phylogenetics and Evolution|volume = 79|pages = 404–414|pmid = 25050928| bibcode=2014MolPE..79..404P }}</ref><ref name=Silva2015>{{cite journal |doi=10.11646/zootaxa.3949.2.9|title=''Rivulus berovidesi'', a new killifish species (Teleostei: Rivulidae) from western Cuba |year=2015|last1=Silva|first1=Rodet Rodriguez|journal=Zootaxa|volume=3949|issue=2|pages=289–96|pmid=25947808}}</ref><ref name=Loureiro2018>{{cite journal | author1 = Loureiro, M. | author2 = R. de Sá | author3 = S.W. Serra | author4 = F. Alonso | author5 = L.S.K. Lanés | author6 = M.V. Volcan | author7 = P. Calviño | author8 = D. Nielsen | author9 = A. Duarte | author10 = G. Garcia | year = 2018 | title = Review of the family Rivulidae (Cyprinodontiformes, Aplocheiloidei) and a molecular and morphological phylogeny of the annual fish genus Austrolebias Costa 1998 | journal = Neotrop. Ichthyol. | volume = 16 | issue = 3 | article-number = e180007 | doi=10.1590/1982-0224-20180007 | doi-access = free | hdl = 20.500.12008/26301 | hdl-access = free }}</ref> If the split into multiple genera is not recognized, ''Rivulus'' contains more than 150 non-annual killifish species found in fresh and brackish waters of the tropical and subtropical Americas, ranging from Argentina in south to Mexico in north, including the Caribbean region.<ref name=Huber2012/>

==Species== Three species are included in ''Rivulus'':<ref name=Costa2011/><ref name=PonceDeLeon2014/><ref name=Silva2015/><ref name=COF>{{Cof genus |Rivulus|access-date=30 January 2021}}</ref>

* ''Rivulus berovidesi'' R. R. Silva, 2015 * ''Rivulus cylindraceus'' Poey, 1860 (Green rivulus) * ''Rivulus roloffi'' Roloff, 1938 (Hispaniolan rivulus)<ref>{{cite iucn|author=Lyons, T.J. |author2= Torres-Pineda, P. |name-list-style=amp |year=2021|title= ''Rivulus roloffi''|article-number= e.T125990534A125990585|doi=10.2305/IUCN.UK.2021-1.RLTS.T125990534A125990585.en|access-date=6 September 2021}}</ref>

A fourth species, ''R. insulaepinorum'', has been recognized, but it is a synonym of ''R. cylindraceus''.<ref name=PonceDeLeon2014/><ref name=COF/> The two Cuban species are close relatives,<ref name=Silva2015/> but the position of the Hispaniolan ''R. roloffi'' has not been confirmed and its placement in this genus is preliminary.<ref name=Costa2011/><ref name=Loureiro2018/>

Because of the disputed validity of the split into several genera, there is a level of confusion about the species included in ''Rivulus'', despite it being clearly defined in 2011.<ref name=Costa2011/> For example, ''"R." azurescens'', ''"R." pivijay'', ''"R." ribesrubrum'', ''"R." tomasi'' and ''"R." xi'' were described in 2013 by authors that did not recognize the split of ''Rivulus'', but noted that they were part of ''Cynodonichthys'' (most species) and ''Laimosemion'' (''"R." tomasi''), by them only considered subgenera of ''Rivulus''.<ref name=Vermeulen2013a>{{cite journal |author1=Vermeulen, F.B.M. |author2=Valdesalici, S. |author3=Garcia-Gil, J.R. | year = 2013 | title = ''Rivulus tomasi'' (Teleostei: Cyprinodontiformes: Rivulidae), a new killifish from Tobogán de la Selva, middle Orinoco river drainage in the Amazonas Territory, southwest Venezuela | journal = Aqua, International Journal of Ichthyology | volume = 19 | issue = 4| pages = 187–192 }}</ref><ref name=Vermeulen2013b>{{cite journal |author=Vermeulen, F.B.M. | year = 2013 | title = Four new species of ''Rivulus'' Poey, 1860, subgenus Cynodonichthys Meek, 1904 (Teleostei: Cyprinidontiformes: Rivulidae) from the Magdalena River Basin, Central Colombia, including notes on ''Rivulus'' (Cynodonichthys) elegans Steindachner, 1880 | journal = Killi-data Series | volume = 2013 |pages = 42–63 }}</ref> This has resulted in the unusual situation where FishBase, despite recognizing the split into several genera, places the newly described species that belong in other genera in ''Rivulus''.<ref name=FishBase>{{FishBase genus | genus = Rivulus| month = March | year = 2019}}</ref>

==References== {{Reflist}}

Category:Rivulidae Category:Freshwater fish genera Category:Taxa named by Felipe Poey Category:Fish of the Dominican Republic