''Xenotoca'' is a

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 ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in 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 ...

Goodeidae Goodeidae is a family of teleost fish endemic to Mexico and some areas of the United States. Many species are known as splitfins. This family contains about 50 species within 18 genera. The family is named after ichthyologist George Brown Goode ...

from

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, where found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma– Grande de Santiago, Panuco,

Cuitzeo Cuitzeo () is a municipality located in the north of the Mexican state of Michoacán. The municipal seat is the town of Cuitzeo del Porvenir It is located in a relatively flat depression around Lake Cuitzeo, a large, very shallow lake, which is ...

and other basins of the

Mesa Central The Central Mexican Plateau, also known as the Mexican Altiplano ( es, Altiplanicie Mexicana), is a large arid-to-semiarid plateau that occupies much of northern and central Mexico. Averaging above sea level, it extends from the United States b ...

. While no goodeid is a very common aquarium fish, the

redtail splitfin The redtail splitfin or redtail goodeid (''Xenotoca eiseni'') is a species of goodeid fish from the family Goodeidae and subfamily Goodeinae. Like other members of Goodeinae, the redtail splitfin is native to Mexico and a livebearer. However, t ...

(''X. eiseni''), is one of the most common aquarium goodeids. Its relatively bright colors offset its reputation for being aggressive towards tankmates, occasionally even killing them. Similarly to that species, two species described in 2016 have males with red-orange tails, but this feature is not shared by the remaining members of the genus. The ''Xenotoca'' species are small, reaching up to in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

Species

There are currently five recognized species in this genus, but two possibly

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...

, tentatively referred to as ''Xenotoca

cf. The abbreviation ''cf.'' (short for the la, confer/conferatur, both meaning "compare") is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that ''cf.'' be used onl ...

melanosoma'' and ''Xenotoca cf. variata'', are known. Genetic work has shown that the genus, as currently defined, is not

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

: The

type species In 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 species that contains the biological type specimen ...

''X. variata'' is distantly related to the remaining, which eventually will be reallocated to their own genus. * '' Xenotoca doadrioi'' Domínguez-Domínguez, Bernal-Zuñiga & Piller, 2016 * '' Xenotoca eiseni'' ( Rutter, 1896) (Redtail splitfin) * '' Xenotoca lyonsi'' Domínguez-Domínguez, Bernal-Zuñiga & Piller, 2016 * '' Xenotoca melanosoma''

Fitzsimons Fitzsimons (also spelled FitzSimons, Fitzsimmons or FitzSimmons) is a surname of Norman origin common in both Ireland and England. The name is a variant of "Sigmundsson", meaning son of Sigmund. The Gaelicisation of this surname is Mac Shíomóin. ...

, 1972 (Black splitfin) * '' Xenotoca variata'' ( T. H. Bean, 1887) (Jeweled splitfin)

References

Endemic fish of Mexico Freshwater fish genera Freshwater fish of Mexico Goodeinae Taxa named by Carl Leavitt Hubbs Ray-finned fish genera Mexican Plateau {{Cyprinodontiformes-stub