Overview

Brief Summary

Taxonomy

General characteristics of Danionella dracula:
  • Body elongate
  • Body depth contained 6-7.5 times in standard length
  • Abdominal region almost circular in cross section, body behind anal fin laterally compressed
  • Caudal peduncle long, narrow, 1.7-2 times in body depth and laterally compressed
  • Head and eye large, mouth supraterminal
  • Upper and lower jaws massive in large males, resulting in longer preorbital distance
  • Nostrils well developed
  • Lateral line canals and pores on head and body absent
  • Dorsal fin short-based, situated opposite posterior half of long-based anal fin
  • Caudal fin furcate with remnants of larval-fin-fold in front of its dorsal and ventral margins
  • Remnant of pre-anal larval-fin-fold present in females only
  • Anus and genital papilla of males located distinctly anterior to anal fin between pelvic fins, in females at typical position in front of anal fin
  • Window (pseudotypanum) present in body musculature rendering pigmented surface of lateral side of anterior gas bladder chamber visible
  • Body muscles greatly thinned out at lateral side of posterior gas bladder chamber
  • Scales absent


Pigmentation-related characteristics:
Pigmentation in alcohol specimens is restricted to:
  • 5 rows of melanophores
    • a broad, mid-dorsal row from head to caudal-fin base
    • a mid-lateral row along horizontal septum from shoulder girdle to hypural plate
    • a ventral row from in front of and slightly above anal-fin base along ventral larval-fin-fold to the end of hypural plate
    • a row along anal-fin base
    • an abdominal, mid-ventral row from ventral tip of cleithrum to anus
  • melanophores capping dorsal and dorsolateral surface of gas bladder chambers and their connecting duct
In life, body is colourless and largely translucent, except for:
  • melanophore patterns described above
  • a thin yellow line running along body at level of neural tube
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Introduction

Danionella dracula is the 3rd species to be discovered in a genus of miniature and highly developmentally-truncated carp-like fishes. It was described scientifically for the first time in 2009 by Museum scientists and their US collaborator.The genus Danionella includes some of the world's smallest fishes and vertebrates.
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Comprehensive Description

Biology

Inhabits small stream (Ref. 81221).
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Distribution

Range Description

This species is only known from the type locality (stream near Sha Du Zup) on the upper Irrawaddy River drainage in northern Myanmar.
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Northern Myanmar.
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Asia: stream near Sha Du Zup in northern Myanmar.
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Distribution conservation

Distribution
Danionella dracula is so far only known from the type locality, a small stream near Sha Du Zup, Kachin state, in northern Myanmar (Burma).


Conservation
Due to the lack of data, the conservation status of this species cannot be assessed.D. dracula has occasionally been exported for the ornamental fish trade, but the impact this might have on the survival of the species is currently unknown.
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Physical Description

Morphology

Vertebrae: 36 - 37
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Size

Max. size

1.7 cm SL (male/unsexed; (Ref. 81221))
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Diagnostic Description

Differs from its congeners, Danionella translucida and Danionella mirifica, in having the following characters: a single bone in the upper jaw (versus two); a single row of 6-13 odontoid processes in males on the dorsal surface of the dentary and on the ventral surface of the upper jaw, the anteriormost processes of which are large and canine-like(versus absence of processes); absence of maxillary-mandibular cartilage (versus presence); the possession of 7C8, 8C7 or 8C8 principal caudal fin rays (versus 9C9), dorsal procurrent rays 3-4 (versus 5-6) and ventral procurrent rays 2-3 (versus 4-6) (Ref. 81221).Description: dorsal-fin rays ii, 4-5, i? anal-fin rays ii, 9-11, i? pectoral-fin rays i, 4, ii; and pelvic-fin rays i, 3, ii in females and i, 4, i in males (Ref. 81221).
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Look Alikes

Lookalikes

Live individuals of D. dracula may be easily confused with the other 3 species of the genus due to their miniature size and lack of easily visible external characters. However, the diagnostic characters listed below - especially the pointed odontoid processes on the jaws of males, which resemble canine-like fangs - guarantee a problem-free identification upon closer inspection with a magnifying glass or microscope.

Diagnostic description
Danionella dracula is distinguished from its congeners, D. translucida and D. mirifica, and D. priapus by:
  • the presence of a single bone in the upper jaw (versus 2)
  • the presence of a single row of 6-13 odontoid processes in males on the dorsal surface of the dentary and on the ventral surface of the upper jaw, the anteriormost processes of which are large and canine-like (versus absence of processes)
  • the lack of the maxillary-mandibular cartilage (versus its presence)
  • the possession of:
    • 7+8, 8+7 or 8+8 principal caudal fin rays (versus 9+9)
    • 3-4 dorsal procurrent rays (versus 5-8)
    • 2-3 ventral procurrent rays (versus 4-8)
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
It is found in small mountain streams in well-oxygenated, fast-flowing waters.

Systems
  • Freshwater
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Environment

benthopelagic; freshwater
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Evolution and Systematics

Evolution

Danionella dracula is a sexually dimorphic, miniature and highly developmentally-truncated cyprinid fish. Compared with its close relative, the zebrafish Danio rerio, it lacks 44 bones or parts thereof and represents one of the most developmentally truncated vertebrates. Absence of the majority of bones appears to be due to developmental truncation via terminal deletion. In contrast to these larval-like features, D. dracula also shows several hyperossifications. Uniquely, among carp-like fishes, male D. dracula have a series of long, pointed odontoid processes on the jaws greatly resembling the jaw dentition of teleosts with true teeth. The anterior-most process in each jaw is extended as a canine-like fang projecting through the epithelium. True jaw teeth are absent from all 3700 species of cypriniforms and were lost at least in the Upper Eocene. It remains to be investigated, however, whether the conserved pathways to regulate tooth development in cypriniforms have been used in D. dracula to form and pattern the odontoid processes. This species represents a remarkable example linking progenetic paedomorphosis via heterochronic change in developmental timing to the evolution of morphological novelties. Danionella dracula was recovered as the sister group of the remaining 3 Danionella species in a molecular analysis, with a split estimated at 29.5 (95% confidence interval 27.4-31.9) million years ago (Britz et al. 2009).
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Danionella dracula

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 3 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

GGCACCCTTTACTTAATCTTTGGGGCCTGGGCTGGAATGGTAGGGACCGCTTTA---AGTCTTCTAATCCGTGCCGAGCTTAACCAACCCGGATCACTTTTAGGAAGT---GATCAGATCTACAATGTAATTGTTACTGCTCATGCTTTTGTAATAATTTTCTTTATAGTAATACCCATTTTAATTGGAGGCTTTGGGAACTGACTAGTCCCATTAATA---ATTGGTGCCCCTGATATAGCATTCCCCCGTATAAATAACATAAGCTTTTGACTCCTTCCACCCTCTTTCCTTCTTCTTTTAGCTTCTTCCGGTGTAGAGGCTGGAGCTGGAACAGGCTGAACAGTATATCCACCACTTGCAGCCAACCTAGGTCACCCAGGAGCTTCAGTAGACCTA---ACTATCTTCTCTCTGCACTTAGCAGGAGTATCCTCAATCTTAGGAGCAATTAATTTTATTACCACCACTATTAACATGAAACCACTAGGAGCCTCTCAATATCAGACACCTTTATTTGTGTGAGCTGTTCTTATTACCGCCGTACTCCTACTATTATCTCTTCCAGTCTTAGCTGCA---GGAATTACAATACTGCTAACAGACCGAAACCTAAATACCTCATTTTTTGATCCGGCAGGGGGAGGGGATCCTATTTTATATCAACACCTTTTCTGATTCTTT
-- end --

Download FASTA File

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Statistics of barcoding coverage: Danionella dracula

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
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Barcode data: Danionella cf. dracula

The following is a representative barcode sequence, the centroid of all available sequences for this species.


No available public DNA sequences.

Download FASTA File
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Statistics of barcoding coverage: Danionella cf. dracula

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2010

Assessor/s
Ng, H.H.

Reviewer/s
Britz, R. & Juffe Bignoli, D.

Contributor/s
Molur, S.

Justification
There is insufficient information regarding the distribution of Danionella dracula, since it is only known from the type locality (on the upper Irrawaddy River drainage in northern Myanmar). Information about its biology and potential threats facing this species is also lacking, and at present it is assessed as Data Deficient.
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Population

Population
The population size and trend of this species is unknown.

Population Trend
Unknown
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Threats

Major Threats
The threats to this species are unknown, since there is no information on the biology of this species and therefore the impact of potential threats (especially those of an anthropogenic nature) remains unknown. The current threats to the area have also not been adequately identified.
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Data deficient (DD)
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
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Management

Conservation Actions

Conservation Actions
More information about the distribution and biology of this species, as well as potential threats, is needed.
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Wikipedia

Dracula fish

The dracula fish, Danionella dracula, is a species of tropical danionin fish from the cyprinid family. It is a freshwater fish indigenous to Burma. A close relative is Brachydanio rerio, the zebrafish of aquariums. It is named dracula after its unusual "fangs": male dracula fish have protruding tooth-like bones stemming from their jawbones. Males have been observed using their fangs to spar with other males.[1][2]

Identified in April 2007[3] from specimens shipped to the United Kingdom in a consignment of aquarium fishes, the dracula fish has so far only been found in the wild in a small stream at Sha Du Zup between Mogaung and Tanai in northern Burma.[2] It is a colourless miniature species and grows to a maximum size of around 17 millimetres (0.67 in).[4] The fish has an elongate body with a large head and eyes. Dracula fish lack scales and the upper body is dominated by the jaws on large males. Much of the fish's structure is cartilaginous: it has 44 fewer bones than the zebrafish, and thus it is translucent and appears similar to larval forms.[1][2] The natural diet of the dracula fish is unknown but in captivity it eats shrimp larvae, small nematodes and fish flakes. Close relatives of the fish feed upon small crustaceans and invertebrates.[5]

The dracula fish is unusual in that its ancestors lost their true teeth around 50 million years ago, but re-evolved its bone fangs as a replacement around 30 million years ago.[2] The species is sexually dimorphic in that the female does not have such prominent bone fangs. It becomes sexually mature while its body is still not fully developed; scientists speculate that this may happen because younger fish were more successful reproductively.[2] Ichthyologist Dr Ralf Britz, who named the fish after Bram Stoker's character Count Dracula, stated that the dracula fish "is one of the most extraordinary vertebrates discovered in the last few decades."[1][4]

References[edit]

  1. ^ a b c Black, Richard (2009-03-11). 'Dracula' fish shows baby teeth. BBC News. Retrieved on 2009-03-11.
  2. ^ a b c d e Ralf Britz, Kevin W. Conway, Lukas Rüber. (2009-03-06). Spectacular morphological novelty in a miniature cyprinid fish, Danionella dracula n. sp.. The Royal Society. Retrieved on 2009-03-11.
  3. ^ Tiny fish developed its own set of dracula fangs. The Times (2009-03-11). Retrieved on 2009-04-30.
  4. ^ a b Devlin, Kate (2009-03-11). New 'dracula' fish discovered. The Daily Telegraph. Retrieved on 2009-03-11.
  5. ^ Jaggard, Victoria (2009-03-11). Photo In The News: New "Dracula" Fish Discovered. National Geographic. Retrieved on 2009-03-12.
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