Bedotiidae

Bedotiidae
Bedotia madagascariensis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Atheriniformes
Suborder:	Atherinoidei
Family:	Bedotiidae Regan, 1903
Genera
Bedotia Rheocles

Bedotiidae are a family of fish in the order Atheriniformes. They are closely related to the Australian rainbowfish family Melanotaeniidae, and were formerly placed in it as a subfamily, but are now considered a distinct family. ^{[1] [2]} They are commonly known as the Madagascar rainbowfish, Madagascan rainbowfish, or Malagasy rainbowfish due to their endemism to Madagascar. It includes two genera, Bedotia and Rheocles.

Taxonomy

This family is monophyletic and includes the two genera Bedotia and Rheocles , with at least 16 species. ^{[3] [4]} This group is considered by Nelson, 2016 Fishes of the World to be a subfamily of the family Melanotaeniidae. ^[5] However, more recent authorities such as Eschmeyer's Catalog of Fishes treat it as its own family. ^[1]

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 (including Telmatherininae). Previously, it was thought that the sister-group relationship between these taxa could be most parsimoniously explained by the break-up of Gondwana. ^[3] However, recent studies incorporating molecular phylogenetics suggest that these groups only diverged during the Eocene, much too recent to be explained by Gondwanan vicariance. Thus, these groups are now thought to descend from a common marine ancestor that independently evolved a freshwater lifestyle on different continents. ^[2]

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. Bedotiins exhibit varying degrees of sexual dimorphism, which is quite pronounced in some species. ^[3] The anal fin spine is weak or absent. ^[6]

Distribution

The entire family of Bedotiidae is endemic to Madagascar. ^[3] 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 basin in the northeast of the island). ^{[3] [7]}

Bedotiin 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. ^[8]

References

1. "CAS - Eschmeyer's Catalog of Fishes". researcharchive.calacademy.org. Retrieved 2025-03-15.
2. Campanella, Daniela; Hughes, Lily C.; Unmack, Peter J.; Bloom, Devin D.; Piller, Kyle R.; Ortí, Guillermo (2015-05-01). "Multi-locus fossil-calibrated phylogeny of Atheriniformes (Teleostei, Ovalentaria)" . Molecular Phylogenetics and Evolution. 86: 8–23. doi:10.1016/j.ympev.2015.03.001. ISSN   1055-7903.
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. Bibcode:2004MolPE..33..719S. doi:10.1016/j.ympev.2004.07.002. PMID   15522799.
4. 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): 1–33.{{cite journal}}: Cite journal requires |journal= (help)
5. J. S. Nelson; T. C. Grande; M. V. H. Wilson (2016). Fishes of the World (5th ed.). Wiley. pp. 358–363. ISBN   978-1-118-34233-6. Archived from the original on 2019-04-08. Retrieved 2019-06-28.
6. Nelson, Joseph S. (2006). Fishes of the World . John Wiley & Sons, Inc. ISBN   0-471-25031-7. OCLC   224053746.
7. Sparks, John S.; Rush, Leila M. R. (2005). "A new rainbowfish (Teleostei: Melanotaenioidei: Bedotiidae) from the southeastern highlands of Madagascar, with comments on the biogeography of Bedotia" (PDF). Zootaxa . 1051: 39–54. doi:10.11646/zootaxa.1051.1.4.
8. Sparks, John S.; Schaefer, S. A. (2001). Schaefer, S. A. (ed.). "Bedotia masoala: A New Species of Atherinoid Rainbowfish (Teleostei: Bedotiidae) from the Masoala Peninsula, Northeastern Madagascar". Copeia . 2001 (2): 482–489. doi:10.1643/0045-8511(2001)001[0482:BMANSO]2.0.CO;2. S2CID   86218849.