Paedocypris

Taxobox
name = Paedocypris
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Cypriniformes
familia = Cyprinidae
subfamilia = Danioninae
genus = "Paedocypris"
genus_authority = Kottelat, Britz, Tan & Witte, 2005
subdivision_ranks = Binomial name
subdivision =
"Paedocypris micromegethes"
Kottelat, Britz, Tan & Witte, 2005
"Paedocypris progenetica"
Kottelat, Britz, Tan & Witte, 2005
"Paedocypris nov. spec. "Bukit Bauk""

"Paedocypris" is an Indonesian genus of fish in the family Cyprinidae (which also includes carps and minnows). Previously the two species, "Paedocypris progenetica" and "Paedocypris micromegethes" were known. In 2006 however, an undescribed third species was discovered in Bukit Bauk, Terengganu in Malaysia. [ [http://rmbr.nus.edu.sg/news/index.php?entry=/southeastasia/20060529-paedocypris_bukitbauk.txt Third species of Paedocypris found in Bukit Bauk, Terengganu, Malaysia] ]

"Paedocypris progenetica" has been claimed to be the smallest known species of fish and vertebrate in the world. The smallest mature female measured 7.9 mm and the largest known individual 10.3 mm.

Taxonomy

Both 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. 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, "Paedocyrpis", and both 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.

"Paedocypris" is considered a danionin genus by Tyson Roberts.cite journal|first=T. R.|last=Roberts|title=The "Celestial pearl danio", a new genus and species of colourful minute cyprinid fish from Myanmar (Pisces: Cypriniformes)|url=http://rmbr.nus.edu.sg/rbz/biblio/55/55rbz131-140.pdf|journal=The Raffles Bulletin of Zoology|year=2007|volume=55|issue=1|pages=131–140|format=PDF] It was found that "Sundadanio" and "Paedocypris" share a sister group relationship, supporting its close relationship to danionin genera; however, this study included danionins among the subfamily Rasborinae. [cite journal|title=Evolution of miniaturization and the phylogenetic position of "Paedocypris", comprising the world's smallest vertebrate|first=Lukas|last=Rüber|coauthors=Kottelat, Maurice; Tan, Heok Hui; Ng, Peter KL; Britz, Ralf|journal=BMC Evolutionary Biology|year=2007|volume=7|issue=38|pages=1–10|doi=10.1186/1471-2148-7-38]

Appearance

Their miniature transparent body lacks typical features characteristic of adult fish, for instance a bony skull structure around its brain, and it retains the post-anal larval-fin-fold along the ventral edge of the caudal peduncle, characteristic of fish larvae. 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. It is hypothesized that these modified fins are used to grasp the female during mating, or to keep position over a spawning surface.

mallest vertebrate

"Paedocypris progenetica" has been claimed to be the smallest known species of fish and vertebrate in the world. The smallest mature female is only 7.9 millimetres (.31 in) standard length, smaller than the female of any other vertebrate "species". The largest known individual is 10.3 mm (.41 in).Maurice Kottelat, Ralf Britz, Tan Heok Hui, Kai-Erik Witte, 2005. "Paedocypris", a new genus of Southeast Asian cyprinid fish with a remarkable sexual dimorphism, comprises the world's smallest vertebrate." "Proceedings of the Royal Society B" 10.1098/rspb.2005.3419. [http://www.journals.royalsoc.ac.uk/(ppwfzp45dtx3n5y3jdpw2u55)/app/home/contribution.asp?referrer=parent&backto=issue,40,84;journal,1,217;homemainpublications,6,7;| Abstract] ]

Male individuals of the species anglerfish "Photocorynus spiniceps" have been documented to be 6.2-7.3 mm at maturity, and thus claimed to be a smaller species. However, these survive only by sexual parasitism, [Sandra Hines, 2006. " [http://www.uwnews.org/article.asp?articleID=22209 Flap over fishes: Who's the smallest of them all?] " "University of Washington News"] and the female individuals reach the significantly larger size of 50.5 mm.Raffles Museum news, 2006. " [http://rmbr.nus.edu.sg/news/index.php?phrase=paedocypris&submit=Search+RMBRnews RMBR: So which is the smallest species of fish in the world? (Part II)] "]

Habitat and conservation

"Paedocypris progenetica" lives in the dark colored peat swamps of the Indonesian island of Sumatra.

"Paedocypris micromegethes" lives in the peat swamps of Sarawak (Borneo). Their small size helps them to survive through extreme droughts, as they can live in small remaining puddles of acid water (pH as low as 2.9, at least 100 times more acidic than rainwater). Their habitat is threatened by forest fires, logging and plantations.

References

External links

* [http://news.bbc.co.uk/2/hi/science/nature/4645708.stm BBC: Scientists find 'smallest fish']
* [http://news.bbc.co.uk/2/hi/science/nature/4666736.stm BBC: Is it really the smallest fish after all?]
* [http://scienceblogs.com/pharyngula/2006/01/paedocypris.php Pharyngula: Paedocypris]
* [http://rmbr.nus.edu.sg/news/index.php Raffles Museum of Biodiversity Research, National University of Singapore]
* [http://hosted.ap.org/dynamic/stories/I/INDONESIA_TINY_FISH?SITE=OKOKL&SECTION=HOME&TEMPLATE=DEFAULT Scientists discover world's smallest fish]
* [http://www.howfishbehave.ca/ Some records in the fish world]