Bedotiinae are a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of the rainbowfish

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 ...

Melanotaeniidae The rainbowfish or Melanotaeniidae is a family of small, colourful freshwater fish found in northern and eastern Australia, New Guinea (including islands in Cenderawasih Bay and Raja Ampat Islands in Indonesia), Sulawesi and Madagascar. The ...

, commonly known as the Madagascar rainbowfish, Madagascan rainbowfish, or Malagasy rainbowfish due to their

endemism Endemism is the state of a species being found 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 found elsew ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

. It includes two

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, ''Bedotia'' and ''Rheocles''.

Anatomy and morphology

As the common name rainbowfish implies, they are generally colorful fishes. Bedotiins are elongated, laterally compressed, and rarely exceed 100 mm 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 ...

. Bedotiins exhibit varying degrees of

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, which is quite pronounced in some species. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

spine is weak or absent.

Distribution

The entire family of Bedotiidae is

endemic Endemism is the state of a species being found 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 found elsew ...

. Bedotiins occur exclusively in freshwater environments and are distributed in small to medium-sized forested rivers and streams, occasionally in swamps and marshes, spanning nearly the entire eastern slope of Madagascar (''R. derhami'' is recorded from a westward draining

Sofia River The Sofia is a river of northwestern Madagascar. It flows through the Sofia Region. The source is at the Tsaratanana Massif at an altitude of 1784 metres. It has a length of . Its mouth is in the Indian Ocean in the Boriziny-Vaovao District Bori ...

basin in the northeast of the island). Bedotiin fishes are under severe threat because of rapid

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...

and habitat modification throughout most of their range. Because ''Bedotia'' and ''Rheocles'' are generally the first to exhibit population declines or disappear from areas where habitat is moderately to highly disturbed or degraded, they are reliable indicators of ecosystem health and stability.

Taxonomy

This subfamily includes the two genera ''Bedotia'' and ''Rheocles'', with at least 16 species. This subfamily is

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 ...

. This group is considered by Nelson, 2016 ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

'' to be a subfamily of the family

. When treated as a family it has been placed by some authorities in a suborder Melanotaenioidei which includes the sister groups Bedotiidae and Melanotaeniidae, as well as

Pseudomugilidae The Pseudomugilidae, the blue-eyes, are a subfamily of atheriniform fish in the rainbowfish family Melanotaeniidae. They inhabit fresh and brackish water in Australia, New Guinea and nearby smaller islands. Blue-eyes are small fish, typically ...

(including

Telmatherininae The Telmatherininae, the sail-fin silversides are a subfamily of Atheriniformes, atheriniform fish from the rainbowfish family, the Melanotaeniidae, inhabiting fresh and brackish water. All but the species ''Kalyptatherina helodes'' are restricte ...

). The sister-group relationship between these taxa is most parsimoniously explained by the break-up of

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

References

{{Taxonbar, from=Q135874 Melanotaeniidae Taxa named by Charles Tate Regan Endemic fauna of Madagascar Fish families