Rheocles

Rheocles is a genus of Madagascar rainbowfish. Rheocles has a restricted distribution, being found only in certain forested freshwater habitats in the central and eastern highlands of Madagascar including the Nosivolo River.[1] The genus appears to feed almost exclusively on allochthonous material, primarily insects falling onto the water surface.[2]

Rheocles
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Atheriniformes
Family: Melanotaeniidae
Subfamily: Bedotiinae
Genus: Rheocles
D. S. Jordan & C. L. Hubbs, 1919
Type species
Eleotris sikorae
Sauvage, 1891
Synonyms
  • Rheocloides Nichols and La Monte, 1931

Taxonomy

In a 1990 study, this genus is monophyletic.[2] However, in a 2004 analysis, it was found that Rheocles was paraphyletic, forming two distinct clades. 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.[3]

Species

There are currently seven recognized species in this genus:[4]

Description

Rheocles species are robust bedotiids with little lateral body compression.[2] R. vatosa and R. derhami are sexually dimorphic, with males exhibiting larger adult size, enhanced coloration and pigmentation, as well as pronounced development of the unpaired fins.[3]

Conservation

Its close association with forested biotopes suggests that, like so many other rainforest-adapted series, Rheocles is extremely vulnerable to deforestation pressure.[1]

References
  1. Stiassny, Melanie L. J.; Reinthal, Peter N. (February 24, 1992). "Description of a New Species of Rheocles (Atherinomorpha, Bedotiidae) from the Nosivolo Tributary, Mangoro River, Eastern Malagasy Republic" (PDF) (3301). American Museum of Natural History: 1–8. Cite journal requires |journal= (help)
  2. Stiassny, Melanie L. J. (August 7, 1990). "Notes on the Anatomy and Relationships of the Bedotiid Fishes of Madagascar, with a Taxonomic Revision of the Genus Rheocles (Atherinomorpha: Bedotiidae)" (PDF) (2979). American Museum of Natural History: 1–33. Cite journal requires |journal= (help)
  3. Sparks, John S.; Smith, W. Leo (2004). "Phylogeny and biogeography of the Malagasy and Australasian rainbowfishes (Teleostei: Melanotaenioidei): Gondwanan vicariance and evolution in freshwater" (PDF). Molecular Phylogenetics and Evolution. 33 (3): 719–734. doi:10.1016/j.ympev.2004.07.002. PMID 15522799.
  4. Froese, Rainer and Pauly, Daniel, eds. (2012). Species of Rheocles in FishBase. June 2012 version.
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