Bedotiidae
Encyclopedia
Bedotiidae is a family
of fish
known as the Madagascar rainbowfish, Madagascan rainbowfish, or Malagasy rainbowfish due to their endemism to Madagascar
. It includes two genera
, Bedotia
and Rheocles
.
. Most bedotiids exhibit varying degrees of sexual dimorphism
, which is quite pronounced in some species.
The anal fin spine is weak or absent.
. Bedotiids 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 basin in the northeast of the island).
Bedotiid fishes are under severe threat because of rapid deforestation
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.
. This group is considered by Nelson, 2006 Fishes of the World
to be a subfamily of the family Melanotaeniidae. In a 2004, this family is placed in a suborder Melanotaenioidei which includes the sister groups Bedotiidae and Melanotaeniidae as well as Pseudomugilidae
(including Telmatherinidae
). The sister-group relationship between Bedotiidae and Melanotaeniidae is most parsimoniously explained by the break-up of Gondwana
.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
known as the Madagascar rainbowfish, Madagascan rainbowfish, or Malagasy rainbowfish due to their endemism to Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. It includes two genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, Bedotia
Bedotia
Bedotia is a genus of the family Bedotiidae of fishes endemic to Madagascar.-Taxonomy:This genus is monophyletic. Little is known regarding phylogenetic interrelationships of the numerous populations of Bedotia of eastern Madagascar, and the genus is in need of systematic revision. One author...
and Rheocles
Rheocles
Rheocles is a genus of Bedotiidae. Rheocles has a restricted distribution, being found only in certain forested freshwater habitats in the central and eastern highlands of Madagascar. The genus appears to feed almost exclusively on allochthonous material, primarily insects falling onto the water...
.
Anatomy and morphology
As the common name rainbowfish implies, they are generally colorful fishes. Bedotiids are elongate, laterally compressed, and rarely exceed 100.0 mm SLFish measurement
Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...
. Most bedotiids exhibit varying degrees of sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, which is quite pronounced in some species.
The anal fin spine is weak or absent.
Distribution
The entire family of Bedotiidae is endemic to MadagascarMadagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. Bedotiids 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 basin in the northeast of the island).
Bedotiid fishes are under severe threat because of rapid deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
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 family includes the two genera Bedotia and Rheocles. There are at least 13 species. This family is monophyleticMonophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
. This group is considered by Nelson, 2006 Fishes of the World
Fishes of the World
Fishes of the World by Joseph S. Nelson is a standard reference for fish systematics. Now in its fourth edition, the work is a comprehensive overview of the 25,000-plus species known to science....
to be a subfamily of the family Melanotaeniidae. In a 2004, this family is placed in a suborder Melanotaenioidei which includes the sister groups Bedotiidae and Melanotaeniidae as well as Pseudomugilidae
Pseudomugilidae
The Blue-eyes are the family of atheriniform fish, the Pseudomugilidae, related to the rainbowfishes. They inhabit fresh and brackish water in Australia and New Guinea. Blue-eyes are small fish, typically no more than in length...
(including Telmatherinidae
Telmatherinidae
The Sail-fin silversides are a family of atheriniform fish, the Telmatherinidae, inhabiting fresh and brackish water . All but one species are restricted to the island of Sulawesi, and most are found solely in the Malili Lakes of that island....
). The sister-group relationship between Bedotiidae and Melanotaeniidae is most parsimoniously explained by the break-up of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
.