Paedocypris

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Paedocypris
Paedocypris progenetica 001.jpg
Paedocypris progenetica
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Subfamily: Danioninae
Genus: Paedocypris
Kottelat, Britz, H. H. Tan & K. E. Witte, 2006
Type species
Paedocypris progenetica
Kottelat, Britz, H. H. Tan & K. E. Witte, 2006

Paedocypris is a genus of tiny cyprinid fish found in swamps and streams on the Southeast Asian islands of Borneo, Sumatra and Bintan. [1]

Contents

Paedocypris progenetica has been claimed to be the one of smallest known species of fish in the world. The smallest mature female measured 7.9 mm (0.31 in) and the largest known individual was 10.3 mm (0.41 in). [1]

Species

The three currently recognized species in this genus are: [2]

Taxonomy

Two species were discovered and identified by ichthyologists Maurice Kottelat from Switzerland and Tan Heok Hui from the Raffles Museum of Biodiversity Research and the National University of Singapore in 1996. [1] Their osteology was studied by Ralf Britz at London's Natural History Museum. In 1994, the same ichthyologists had already discovered in Sarawak (Malaysian part of Borneo) another miniature species of the same genus Paedocypris. Like P. progenetica, P. micromegethes was found in the slow-flowing blackwater streams and peat swamps.

The genus, Paedocypris, and two species, Paedocypris progenetica and Paedocypris micromegethes, were first described in 2006. Paideios is Greek for children and cypris is Greek for Venus and is a common suffix for cyprinid genera; the gender is feminine. Progenetica (from the word progenetic) is used as an adjective. Micromegethes is Greek for small in size, and is used as a noun in apposition. [1]

Paedocypris is considered a danionin genus by Tyson Roberts. [4] Sundadanio and Paedocypris were found to share a sister group relationship, supporting its close relationship to danionin genera; however, this study included danionins among the subfamily Rasborinae. [5]

Appearance

Their miniature transparent bodies lack the typical features characteristic of adult fish, for instance a mineralised braincase, and it retains the postanal larval fin-fold along the ventral edge of the caudal peduncle, characteristic of fish larvae. [6] They have a unique sexual dimorphism: The males have highly modified pelvic fins, with the first ray terminating with a hook-like projection of keratinized skin, supported by hypertrophied pelvic musculature. Males also have a pad of keratinized skin in front of the pelvic fins. These modified fins are thought to be used to grasp the female during mating, or to keep position over a spawning surface.

Smallest vertebrate

Paedocypris progenetica has been claimed to be the smallest known species of fish and vertebrate in the world, particularly before the description of the frog Paedophryne amauensis in 2012. [7] The smallest mature P. progenetica female is only 7.9 mm (0.31 in) in standard length, smaller than the female of any other vertebrate species, including those of P. amauensis. The largest known individual is 10.3 mm (0.41 in). [1]

Male individuals of the anglerfish species Photocorynus spiniceps have been documented to be 6.2–7.3 mm (0.24–0.29 in) at maturity, and thus claimed to be a smaller species. However, these survive only by sexual parasitism, [8] and the female individuals reach the significantly larger size of 50.5 mm (1.99 in). [9]

During their evolution where they have adapted to their environment and shrunk in size, they have lost least seven and possibly as many as ten percent of their Hox genes (about 15–20 percent of the total amount) and much of their transposons, and their introns are much reduced. Because of their small size and development due to a simplification of their genome, their skull consist of cartilage, about 40 of their skeletal bones will never be properly developed and the ribs are reduced and remain poorly ossified. Other groups of fish which live in the same environment have not gone through the same types of genetic and developmental changes. [10] [11] [12]

Habitat and conservation

Paedocypris progenetica lives in the blackwater peat swamps of the Indonesian islands of Sumatra and Bintan. [1] P. micromegethes lives in the peat swamps of Sarawak in northern Borneo, Malaysia. [1] P. carbunculus is found in peat swamps in Central Kalimantan, Borneo, Indonesia. [3] Members of this genus are habitat specialists that only live in acidic water. Within peat swamp forests, they are usually found to inhabit deeper, cooler water layers close to the bottom half of the water columns. They also tend to inhabit shaded areas in which light is usually absent from their environment. Their small size helps them to survive droughts, as they can live in small remaining puddles. However, their small ranges and specialised habitat make them extremely vulnerable to habitat loss, such as drainage of peat swamps and fires, and some populations have already disappeared. [1] It has been speculated that some other miniature fish from the habitat and region may already have become extinct, even before being scientifically described or discovered. [1] [13] In Malaysia alone, it has been estimated that—in addition to Paedocypris—up to 15% of the freshwater fish species are associated with peat swamps, [1] and based on current destruction rates all Bornean and Sumatran peatlands may be gone by 2040. [14]

Related Research Articles

<span class="mw-page-title-main">Cyprinidae</span> Family of freshwater fish

Cyprinidae is a family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barbs and barbels, among others. Cyprinidae is the largest and most diverse fish family, and the largest vertebrate animal family overall, with about 3,000 species; only 1,270 of these remain extant, divided into about 200 valid genera. Cyprinids range from about 12 mm (0.5 in) in size to the 3 m (9.8 ft) giant barb. By genus and species count, the family makes up more than two-thirds of the ostariophysian order Cypriniformes. The family name is derived from the Greek word kyprînos.

<i>Pangio</i> Genus of fishes

Pangio is a genus of small Asian freshwater fish in the true loach family Cobitidae. In earlier taxonomic schemes it was known as Acanthophthalmus. The "kuhli loach" is well-known in the aquarium trade and commonly identified as P. kuhlii, but most individuals actually appear to be P. semicincta.

<i>Danionella</i> Genus of fishes

Danionella is a genus of danionin fish found in freshwater habitats in Myanmar and West Bengal, India. It includes some of the smallest fishes.

<i>Sundadanio</i> Genus of fishes

Sundadanio is a genus of cyprinid fishes from freshwater habitats, typically peat swamps and blackwater streams, in Borneo and Sumatra in southeast Asia. At up to 2.3 cm (0.91 in) in standard length they are very small, but still larger than their close relatives Paedocypris. Species of the two genera are often found together.

<i>Paedocypris progenetica</i> Species of fish

Paedocypris progenetica is a species of tiny cyprinid fish endemic to the Indonesian islands of Sumatra and Bintan where it is found in peat swamps and blackwater streams. It was discovered by Singaporean ichthyologist Heok Hui Tan. He has written a description of the fish along with another species of the same genus called Paedocypris micromegethes.

<i>Sundadanio axelrodi</i> Species of fish

Sundadanio axelrodi is a danionin in the family Cyprinidae, with origin from Borneo, Bangka, and Sumatra. Originally described as a rasbora, Rasbora axelrodi, this tiny species was later deemed to be more closely related to the danios but not enough to be moved into the genus Danio. Sundadanio axelrodi reaches a maximum size of 1.7 cm. Sundadanio was considered monotypic until the genus was reassessed by Conway, Kottelat and Tan in 2011.

Maurice Kottelat is a Swiss ichthyologist specializing in Eurasian freshwater fishes.

<i>Betta</i> Genus of fish

Betta is a large genus of small, active, often colorful, freshwater ray-finned fishes, in the gourami family (Osphronemidae). The best known Betta species is B. splendens, commonly known as the Siamese fighting fish and often kept as an aquarium pet.

Paedocypris micromegethes is a species of cyprinid fish endemic to Sarawak in East Malaysia, where it is found in peat swamps. It is one of the smallest vertebrates in the world, with females reaching a maximum size of 11.6 mm.

<span class="mw-page-title-main">Danionin</span> Subfamily of fishes

The danionins are a group of small, minnow-type fish belonging to the family Cyprinidae. Species of this group are in the genera clades danio and devario, based on the latest phylo-genetic research by Fang et al in 2009. They are primarily native to the fresh waters of South and Southeast Asia, with fewer species in Africa. Many species are brightly coloured and are available as aquarium fish worldwide. Fishes of the danio clade tend to have horizontal stripes, rows of spots, or vertical bars, and often have long barbels. Species within the devario dlade tend to have vertical or horizontal bars, and short, rudimentary barbels, if present at all. All danionins are egg scatterers, and breed in the rainy season in the wild. They are carnivores, living on insects and small crustaceans.

Fangfangia spinicleithralis is a species of cyprinid fish endemic to Indonesia where it is found in the peat swamp forests of Kalimantan Tengah, Borneo. It is the only member of its genus. The genus name Fangfangia honors the Chinese-Swedish ichthyologist Fang Fang Kullander (1962-2010), who specialized in the study of cyprinid fishes.

Paedocypris carbunculus is a tiny species of cyprinid fish endemic to peat swamps and blackwater streams in Central Kalimantan, Borneo, Indonesia. It is the most recently described species of the three in the genus Paedocypris and it reaches up to 11.5 mm (0.45 in) in standard length. This shoaling species has been kept and bred for several generations in aquariums.

Cyanogaster noctivaga is a species of characin native to the Rio Negro, Brazil. This species is the only known member of the genus Cyanogaster and its scientific name translates as the blue-bellied night wanderer, referring to its unique appearance and nocturnal habits. It was first described in 2013, having been discovered in October 2011 on a scientific expedition organised by the University of São Paulo, Brazil.

Sundadanio echinus is a danionin in the family Cyprinidae. It is endemic to Borneo and found in West Kalimantan (Indonesia) and western Sarawak (Malaysia). It lives in peat swamps and blackwater streams.

Sundadanio margarition is a danionin in the family Cyprinidae. It is endemic to Sarawak, Malaysian Borneo, and known from the Rajang and Sarawak River drainages. It lives in coastal peat swamp forests.

Sundadanio retiarius is a danionin in the family Cyprinidae. It is endemic to Kalimantan, Indonesian Borneo, and known from the Kotawaringin and Kahayan River drainages. It lives in peat swamps and blackwater streams.

Sundadanio rubellus is a danionin in the family Cyprinidae. It is endemic to Kalimantan, Indonesian Borneo, and known from the southern Kapuas River delta. It lives in peat swamp forests.

Heok Hui Tan is a Singaporean ichthyologist at the Lee Kong Chian Natural History Museum of the National University of Singapore. Dr. Tan's main interest lies in the systematics of Southeast Asian freshwater fishes, encompassing taxonomy, ecology and biogeography. His primary areas of research focus on neglected and de novo habitats such as peat swamp forests, swamp forests, and rapids.

<i>Rasbora marinae</i>

Rasbora marinae, or Marina's rasbora, is a recently described species of cyprinid fish in the genus Rasbora, in 2020. Several Rasbora specimens from 1996 - 2005, resembling R. cephalotaenia were examined and found to be a new species, due to their unique body pattern in adulthood.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Kottelat, Maurice; Britz, Ralf; Heok Hui, Tan; Witte, Kai-Erik (2005). "Paedocypris, a new genus of Southeast Asian cyprinid fish with a remarkable sexual dimorphism, comprises the world's smallest vertebrate" (PDF). Proceedings of the Royal Society B: Biological Sciences. 273 (1589): 895–899. doi:10.1098/rspb.2005.3419. PMC   1560243 . PMID   16627273. Archived from the original (PDF) on 12 July 2009. Retrieved 26 October 2012.
  2. ↑ Froese, Rainer and Pauly, Daniel, eds. (2013). Species of Paedocypris in FishBase . February 2013 version.
  3. 1 2 Kottelat, Maurice; Britz, Ralf (2008). "Paedocypris carbunculus, a new species from Borneo (Teleostei: Cypriniformes: Cyprinidae)" (PDF). Raffles Bulletin of Zoology . 56 (2): 415–422. Retrieved 26 October 2012.
  4. ↑ Roberts, T. R. (2007). "The "Celestial pearl danio", a new genus and species of colourful minute cyprinid fish from Myanmar (Pisces: Cypriniformes)" (PDF). Raffles Bulletin of Zoology . 55 (1): 131–140. Retrieved 2009-06-24.
  5. ↑ Rüber, Lukas; Kottelat, Maurice; Tan, Heok Hui; Ng, Peter KL; Britz, Ralf (2007). "Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate". BMC Evolutionary Biology. 7: 1–10. doi: 10.1186/1471-2148-7-38 . PMC   1838906 . PMID   17355618.
  6. ↑ Britz, Ralf; Conway, Kevin W.; Rüber, Lukas (2014-10-08). "Miniatures, morphology and molecules: Paedocypris and its phylogenetic position (Teleostei, Cypriniformes)". Zoological Journal of the Linnean Society. 172 (3): 556–615. doi: 10.1111/zoj.12184 . ISSN   0024-4082.
  7. ↑ Rittmeyer, E. N.; Allison, A.; Gründler, M. C.; Thompson, D. K.; Austin, C. C. (2012). "Ecological guild evolution and the discovery of the world's smallest vertebrate". PLOS ONE. 7 (1): e29797. Bibcode:2012PLoSO...729797R. doi: 10.1371/journal.pone.0029797 . PMC   3256195 . PMID   22253785.
  8. ↑ Sandra Hines, 2006. "Flap over fishes: Who's the smallest of them all? Archived 2006-02-12 at the Wayback Machine " University of Washington News
  9. ↑ Raffles Museum news, 2006. "RMBR: So which is the smallest species of fish in the world? (Part II)"
  10. ↑ The strange genetics of the fish that never grows up
  11. ↑ Highlight: Big Surprises from the World’s Smallest Fish
  12. ↑ The Most Developmentally Truncated Fishes Show Extensive Hox Gene Loss and Miniaturized Genomes
  13. ↑ BBC (25 January 2006). Scientists find 'smallest fish'. Retrieved 24 September 2017.
  14. ↑ Butler, R.A. (26 January 2006). Picture of the world's smallest fish. Mongobay. Retrieved 24 September 2017.

[1]

  1. ↑ Kottelat, M., Britz, R., Hui, T., & Witte, K. (2006). Paedocypris, a New Genus of Southeast Asian Cyprinid Fish with a Remarkable Sexual Dimorphism, Comprises the World's Smallest Vertebrate. Proceedings: Biological Sciences, 273(1589), 895-899.
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