''Poecilia petenensis'', the Petén molly, is a

poeciliid Poeciliidae are a 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, molly, platy, and swordtail. The original distribution of the fam ...

fish species

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to Guatemala.

Taxonomy

The Petén molly is a short-finned molly (part of the ''

Poecilia sphenops ''Poecilia sphenops'', called the Mexican molly or simply the molly, is a species of poeciliid fish from Central America. It was once understood as a widespread species with numerous local variants ranging from Mexico to Venezuela, but these vari ...

complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...

) whose

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

is a matter of some confusion. It was originally described by Günther (1866), who named it ''Poecilia petenensis''. Günther (1866) also described the swordtail molly under the name '' Mollienesia petenensis''. Regan (1913) placed both mollies in the genus ''

Mollienesia ''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish water, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have ...

'', renaming the short-finned species ''Mollienesia gracilis''. When

Rosen Rosen is a surname of German and Ashkenazi Jewish origin, the name deriving from the German word for roses. Notable people with this surname include: Places *Rosen, Burgas Province, Bulgaria * Rosen, Dobrich Province, Bulgaria * Rosen, Minnesota, ...

and Bailey (1963) revised the

poeciliids Poeciliidae are a 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, molly, platy, and swordtail. The original distribution of the famil ...

, they placed both the swordtail and the short-finned molly in the genus ''

Poecilia ''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have adapted to livi ...

'' and made the short-finned species a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

for ''Poecilia sphenops''. Poeser (2002) revalidated ''Poecilia petenensis'' as a separate species, leading to homonymity with the swordtail species, which was duly renamed ''Poecilia kykesis''. Meyer et al. hold that Poeser (2002) broke

nomenclature codes Nomenclature codes or codes of nomenclature are the various rulebooks that govern the naming of living organisms. Standardizing the scientific names of biological organisms allows researchers to discuss findings (including the discovery of new s ...

. They argue that the designation ''Poecilia petenensis'' should continue to refer to the swordtail molly and that the short-finned molly should instead be named ''Poecilia gracilis''.

Description

The largest examined ''Poecilia petenensis'' female measured 119 mm in

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

, while the largest males attained 93 mm. The body is relatively slender, more so than in the otherwise similar species '' P. teresae'', and somewhat higher in the males than in the females. The sides of the fish are spotted, which is more pronounced in females. Larger females exhibit a diamond pattern on their sides. The fins are mostly without pigment.

Distribution

''Poecilia petenensis'' is

to the freshwater

Lake Petén Itzá Lake Petén Itzá (''Lago Petén Itzá'', ) is a lake in the northern Petén Department in Guatemala. It is the third largest lake in Guatemala, after Lake Izabal and Lake Atitlán. It is located around . It has an area of , and is some long a ...

in Guatemala.

References

{{Taxonbar, from=Q3759049 petenensis Taxa named by Albert Günther Fish described in 1866 Fish of Guatemala Freshwater fish of North America Endemic fauna of Guatemala