''Heterandria'' 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 livebearing fishes within the family

Poeciliidae Poeciliidae are a Family (biology), family of freshwater ray-finned fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, Poecilia, molly, Platy (fish), platy, and Green swo ...

. 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), ...

occur in

Guatemala Guatemala, officially the Republic of Guatemala, is a country in Central America. It is bordered to the north and west by Mexico, to the northeast by Belize, to the east by Honduras, and to the southeast by El Salvador. It is hydrologically b ...

and its surroundings, particularly

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

, but the midget livebearer ('' H. formosa'') comes from the southeastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. Though many Poecilidae are familiar

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

fishes, e.g.

guppies The Greater Underwater Propulsion Power Program (GUPPY) was initiated by the United States Navy after World War II to improve the submerged speed, maneuverability, and endurance of its submarines. (The "Y" in the acronym was added for pronouncea ...

, mollies, platys and

swordtail ''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. ''Xiphophorus'' species can be divided into three groups based on their evoluti ...

s, species within ''Heterandria'' are not commonly kept as pets. Somewhat more frequently found in aquaria is ''H. formosa'', perhaps because it is one of the smallest known fish species in the world; its diminutive males are probably the smallest fish easy to keep as a pet. Species in this genus resemble egg-laying

Cyprinodontoidei Cyprinodontoidei is a suborder of fishes, one of the two suborders in the order Cyprinodontiformes. The Cyprinodontoidei consists of eleven families which are found in the Americas, the Mediterranean and in Africa, including Madagascar. Classi ...

such as

Fundulidae Fundulidae is the family of topminnows and North American killifishes. Distribution The 46 species are native to North America as far south as Yucatan, and to the islands of Bermuda and Cuba, occurring in both freshwater and marine environment ...

(topminnows) at first glance, and are thus sometimes called "

killifish A killifish is any of various oviparous (egg-laying) cyprinodontiform fish, including families Aplocheilidae, Pantanodontidae, Cyprinodontidae, Fundulidae, Nothobranchiidae, Profundulidae, Aphaniidae and Valenciidae. All together, there ar ...

" though this is technically erroneous.

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

(2009)
''Heterandria'' species
Retrieved April 8, 2009.

Species

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

currently recognizes 3 species in this genus, but based on

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...

, external characters,

morphometrics Morphometrics (from Greek μορΦή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are co ...

and

meristics Meristics is an area of zoology and botany which relates to counting quantitative features of animals and plants, such as the number of fins or scales in fish. A meristic (countable trait) can be used to describe a particular species, or used to i ...

''H. formosa'' (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) is not closely related to the remaining, which have been moved to their own genus, ''Pseudoxiphophorus''.Agorreta, A.; Domínguez-Domínguez, O.; Reina, R.G.; Miranda, R.; Bermingham, E.; and Doadrio, I. (2013). ''Phylogenetic relationships and biogeography of Pseudoxiphophorus (Teleostei: Poeciliidae) based on mitochondrial and nuclear genes.'' Mol Phylogenet Evol. 2013 Jan;66(1):80-90 There are probably more remaining undiscovered as these fishes are rather inconspicuous. However, it is not very likely that many species remain unknown to science as this genus is only found in a rather restricted region, and only one new species has been discovered since 1980. The three species classified under this genus are: * ''

Heterandria attenuata ''Heterandria'' is a genus of livebearing fishes within the family Poeciliidae. Most species occur in Guatemala and its surroundings, particularly Mexico, but the midget livebearer ('' H. formosa'') comes from the southeastern United States ...

'' D. E. Rosen & R. M. Bailey, 1979 * ''

Heterandria formosa ''Heterandria formosa'' (known as the least killifish, dwarf topminnow, mosqu or midget livebearer) is a species of livebearing fish within the family Poeciliidae. This is the same family that includes familiar aquarium fishes such as guppies an ...

'' Girard, 1859 (Dwarf livebearer, least killifish) * ''

Heterandria tuxtlaensis ''Heterandria'' is a genus of livebearing fishes within the family Poeciliidae. Most species occur in Guatemala and its surroundings, particularly Mexico, but the midget livebearer ('' H. formosa'') comes from the southeastern United States ...

'' McEachran & T. J. DeWitt, 2008

References

{{Authority control Poeciliidae Ovoviviparous fish Fish of Central America Freshwater fish of Mexico Fish of the United States Freshwater fish genera Taxa named by Louis Agassiz Ray-finned fish genera de:Heterandria