''Leptolebias'' is a

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

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 the

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 ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Rivulidae The Rivulidae are a family (biology), family of killifishes in the order (biology), order Cyprinodontiformes. They are commonly known as rivulids, South American killifish or New World killifish. The latter names are slightly misleading, however, ...

. Like many of their relatives, they are rather ambiguously known as "

pearlfish Pearlfish are marine fish in the ray-finned fish family Carapidae. Pearlfishes inhabit the tropical waters of the Atlantic, Indian, and Pacific Oceans at depths to , along oceanic shelves and slopes. They are slender, elongated fish with no s ...

". They are

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 the coastal areas of

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, where they inhabit ephemeral pools in

tropical forest Tropical forests are forested ecoregions with tropical climates – that is, land areas approximately bounded by the Tropic of Cancer, tropics of Cancer and Tropic of Capricorn, Capricorn, but possibly affected by other factors such as prevailing ...

s like the Mata Atlântica (or what remains thereof) and restinga. Rare and little-known, the entire genus seems to be close to

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

ion. Specifically, ''Leptolebias'' species have been found in two regions to date: between Maricá and Vila de Cava in

Rio de Janeiro state Rio de Janeiro () is one of the 27 federative units of Brazil. It has the second largest economy of Brazil, with the largest being that of the state of São Paulo. The state, which has 8.2% of the Brazilian population, is responsible for 9.2% of ...

, and between Itanhaém in southern

São Paulo state SAO or Sao may refer to: Places * Sao civilisation, in Middle Africa from 6th century BC to 16th century AD * Sao, a town in Boussé Department, Burkina Faso * Serb Autonomous Regions (''Srpska autonomna oblast'', SAO), during the breakup of ...

and the

Paranaguá Paranaguá (Tupi language, Tupi, 'Great Round Sea') is a city in the state of Paraná (state), Paraná in Brazil. Founded in 1648, it is Paraná's oldest city. It is known for the Port of Paranaguá, which serves as both the sea link for Curitiba, ...

bay

catchment area A catchment area in human geography, is the area from which a location, such as a city, service or institution, attracts a population that uses its services and economic opportunities. Catchment areas may be defined based on from where people are ...

in Paraná state.

Description

These small fishes measure only 2–3 cm (around one inch) 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 ...

. The females are colored uniformly brown, without darker markings, as are the females of some related killifishes. The males may have some dark pigmentation, but it does not extend into the

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

, as it does in many related genera. Otherwise, they are mainly colored in bright reddish and yellow hues, with

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstruc ...

or similarly conspicuous spots on the sides; their opercular region bears red horizontal stripes that usually interconnect to form a web-like pattern. The

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

of ''Leptolebias'' species is elongated and longer than deep, and the members of this genus have a single anterior supraorbital neuromast. .

Systematics

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

study revealed that the genus ''Leptolebias'' in the old circumscription was

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

: some species often placed here are actually less closely related to 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 ...

''L. marmoratus''; the marbled pearlfish; than the related genera '' Campellolebias'' and '' Cynopoecilus'' are. These species have subsequently been separated in '' Notholebias''. There are proposals to move other species to '' Leptopanchax'', '' Mucurilebias'' and '' Notholebias''.

Species

The currently recognized species in this genus are:Costa, W.J.E.M. (2014)
A new genus of miniature cynolebiasine from the Atlantic Forest and alternative biogeographical explanations for seasonal killifish distribution patterns in South America (Cyprinodontiformes: Rivulidae).
''Vertebrate Zoology, 64 (1): 23–33. '' * '' Leptolebias aureoguttatus'' ( da Cruz, 1974) * '' Leptolebias citrinipinnis'' ( W. J. E. M. Costa, Lacerda & Tanizaki, 1988) * '' Leptolebias itanhaensis'' W. J. E. M. Costa, 2008 * '' Leptolebias marmoratus'' ( Ladiges, 1934) (marbled pearlfish) * '' Leptolebias opalescens'' ( G. S. Myers, 1942) (opalescent pearlfish) * '' Leptolebias splendens'' (G. S. Myers, 1942) (splendid pearlfish)

References

{{Taxonbar, from=Q1758669 Rivulidae Freshwater fish genera Taxa named by George S. Myers