Rheocles
Encyclopedia
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 surface.
. However, in a 2004 analysis, it was found that Rheocles was paraphyletic
, forming two distinct clade
s. R. alaotrensis, R. lateralis, and R. wrightae (all species that are not discernibly sexually dimorphic
was recovered as the sister taxon
of the rest of the bedotiids, including Bedotia sister to R. vatosa + R. derhami. R. pellegrini and R. sikorae were excluded from this study due to lack of available material, however, R. sikorae is considered to be the sister taxon to R. wrightae.
, with males exhibiting larger adult size, enhanced coloration and pigmentation, as well as pronounced development of the unpaired fins.
pressure.
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...
of Bedotiidae
Bedotiidae
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.-Anatomy and morphology:...
. Rheocles has a restricted distribution, being found only in certain forested freshwater habitats in the central and eastern highlands of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. The genus appears to feed almost exclusively on allochthonous material, primarily insects falling onto the water surface.
Taxonomy
In a 1990 study, this genus 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...
. However, in a 2004 analysis, it was found that Rheocles was paraphyletic
Paraphyly
A group of taxa is said to be paraphyletic if the group consists of all the descendants of a hypothetical closest common ancestor minus one or more monophyletic groups of descendants...
, forming two distinct clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s. R. alaotrensis, R. lateralis, and R. wrightae (all species that are not discernibly sexually dimorphic
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:...
was recovered as the sister taxon
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
of the rest of the bedotiids, including Bedotia sister to R. vatosa + R. derhami. R. pellegrini and R. sikorae were excluded from this study due to lack of available material, however, R. sikorae is considered to be the sister taxon to R. wrightae.
Description
Rheocles species are robust bedotiids with little lateral body compression. R. vatosa and R. derhami are sexually dimorphicSexual 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:...
, with males exhibiting larger adult size, enhanced coloration and pigmentation, as well as pronounced development of the unpaired fins.
Conservation
Its close association with forested biotopes suggests that, like so many other rainforest-adapted series, Rheocles is extremely vulnerable to deforestationDeforestation
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....
pressure.