Overview

Brief Summary

Taxonomy

Atretochoana eiselti can be readily distinguished from other caecilians by its sealed internal nostrils and massive mouth.It was originally described as a species of the genus Typhlonectes (Taylor, 1968) but was subsequently placed in its own genus by Nussbaum and Wilkinson (1996). Although it is more closely related to Potomotyphlus than to Typhlonectes (Wilkinson and Nussbaum, 1998), it is morphologically very different from both these genera of aquatic caecilians.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Natural History Museum, London

Partner Web Site: Natural History Museum

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Introduction

Atretochoana eiselti is a large, presumably aquatic, caecilian amphibian with a broad, flat head and a fleshy dorsal fin on the body.It is one of the most enigmatic amphibians and the largest lungless tetrapod, more than twice the size of any other, and its skull is very different from that of other caecilians.No living populations of A. eiselti have been found and only 2 preserved specimens are known.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Natural History Museum, London

Partner Web Site: Natural History Museum

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Comprehensive Description

Description

Atretochoana eiselti is one of the longest typhlonectids, with the holotype having a total length of 738 mm, with subsequent specimens reaching 1 meter in length (Hoogmoed et al 2011). Based on Wilkinson et al. (1998), this caecilian has a dorsoventrally compressed head, with dorsal eyes in shallow ocular depression; nares countersunk, cheek curved with lower jaws countersunk laterally. The skin is wrinkled, light blue-grey dorsally, lighter ventrally. A white patch is present on the ventral surface of the head between the mandibles and the anterior annuli. The tip of the snout and the areas bordering the mouth are more olive-grey.

A. eiselti is particularly unusual because it lacks lungs, making it the largest lungless tetrapod. The choanal apertures are permanently sealed by fleshy flaps of tissue (Wilkinson and Nussbaum 1997).

  • Wilkinson, M. and Nussbaum, R.A. (1997). ''Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae).'' Biological Journal of the Linnean Society, 62, 39-109.
  • Wilkinson, M., Sebben, A., Schwartz, E.N.F., and Schwartz, C.A. (1998). ''The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil.'' Journal of Natural History, 32, 617-627.
  • Hoogmoed, M.S., Maciel, A.O., and Coragem, J.T. (2011). ''Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia.'' Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais, 6(3), 241-262.
Creative Commons Attribution 3.0 (CC BY 3.0)

© AmphibiaWeb © 2000-2011 The Regents of the University of California

Source: AmphibiaWeb

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Biology

Atretochoana eiselti is thought to breathe through its skin (cutaneous gas exchange). The absence of lungs is compensated for by skin that is richly supplied with capillaries which penetrate to the outer layer, the epidermis. It is presumed to be aquatic and probably lives in fast-flowing water.The species has a radically divergent skull morphology that differs from all other caecilians in having:
  • a massively enlarged mouth (produced by a posteriorly displaced jaw articulation)
  • a highly mobile 'cheek'
  • very strange elongate stapes from which muscles unknown in any other organism originate
Nothing is known about the behaviour of A. eiselti, but it is likely to be a predator and/or scavenger.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Natural History Museum, London

Partner Web Site: Natural History Museum

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution

Range Description

This species is extremely poorly known. One specimen comes from an unspecified location in South America, and a second specimen comes from an unspecified location in Brazil.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution and Habitat

Until the summer of 2011, Aretochoana eiselti was known from only two specimens with unknown locality information. The holotype is marked simply "South America"; the other specimen is probably from Brazil (Wilkinson et al. 1998). In 2011, Hoogmoed and colleagues describe the first specimens with locality information as well as observations in the field, specifically from near the mouth of the Amazon River and the other from 2000 km away in the Madeira River near the border of Brasil and Bolivia (Rondônia state). Wilkinson and Nussbaum (1997) appear to be correct in speculating that it is aquatic; however, the live specimens were found in lowland, warm, turbid waters dispel their hypothesis of preferring montane areas with cold, fast-moving water (Hoogmoed et al 2011). Much remains to be understood of its distribution which is undoubted broad given the large extent between the specimens and observations that Hoogmoed and colleagues report (2011), including a large female that was found in a tidal pool at low tide near Belem on the Atlantic coast.

  • Wilkinson, M. and Nussbaum, R.A. (1997). ''Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae).'' Biological Journal of the Linnean Society, 62, 39-109.
  • Wilkinson, M., Sebben, A., Schwartz, E.N.F., and Schwartz, C.A. (1998). ''The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil.'' Journal of Natural History, 32, 617-627.
  • Hoogmoed, M.S., Maciel, A.O., and Coragem, J.T. (2011). ''Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia.'' Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais, 6(3), 241-262.
Creative Commons Attribution 3.0 (CC BY 3.0)

© AmphibiaWeb © 2000-2011 The Regents of the University of California

Source: AmphibiaWeb

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution conservation

Distribution
No living populations of Atretochoana eiselti are known and there are just 2 known preserved specimens:
  1. The type specimen is in the collection of the Naturhistorisches Museum in Vienna. The only locality data for this specimen is 'South America' and information on how it came into the collection is lacking.
  2. The second specimen is in the collections of the Universidade de Brasilia and also lacks any associated data.
Despite the lack of locality data, the species is presumed to be from Brazil.

Conservation
Given the lack of data about the distribution, ecology and abundance of Atretochoana eiselti, its conservation status cannot be determined. It is categorised by the International Union for Conservation of Nature (IUCN) as Data Deficient.It seems likely that A. eiselti is not very common and that it does not have a very broad distribution. The fact that we don't know the location of even a single living population is the biggest threat to the survival of this species.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Natural History Museum, London

Partner Web Site: Natural History Museum

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This is an aquatic, presumably viviparous species, possibly associated with cold, fast-flowing, well-oxygenated streams. It is the only lungless caecilian.

Systems
  • Freshwater
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2004

Assessor/s
Mark Wilkinson, John Measey, Marvalee Wake

Reviewer/s
Global Amphibian Assessment Coordinating Team (Simon Stuart, Janice Chanson, Neil Cox and Bruce Young)

Contributor/s

Justification
Listed as Data Deficient in view of continuing uncertainties as to its extent of occurrence, status and ecological requirements.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Population

Population
It is known only from two specimens.

Population Trend
Unknown
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History, Abundance, Activity, and Special Behaviors

Quartz crystals were found in the gut of one specimen, but no useful food remains were present (Wilkinson et al. 1998). Little is known of its life history or behavior although Hoogmoed et al (2011) report that A. eiselti were captured in baited shrimp traps set in shallow waters off of Praia de Marahu on Mosqueiro island north of Belem. They also report that individuals were seen swimming at the surface of the rivers and conjecture that A. eiselti is a strong swimmer given the currents at the Amazon River mouth and the Madeira River.

  • Wilkinson, M. and Nussbaum, R.A. (1997). ''Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae).'' Biological Journal of the Linnean Society, 62, 39-109.
  • Wilkinson, M., Sebben, A., Schwartz, E.N.F., and Schwartz, C.A. (1998). ''The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil.'' Journal of Natural History, 32, 617-627.
  • Hoogmoed, M.S., Maciel, A.O., and Coragem, J.T. (2011). ''Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia.'' Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais, 6(3), 241-262.
Creative Commons Attribution 3.0 (CC BY 3.0)

© AmphibiaWeb © 2000-2011 The Regents of the University of California

Source: AmphibiaWeb

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Threats

Major Threats
There is no information on threats to this species.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History, Abundance, Activity, and Special Behaviors

Specimens collected from Rondônia, Brasil, were found in drying pools from the upstream damming of channels in preparation for the new hydroelectric plant Santo Antonio in the Madeira River. At the other site, Hoogmoed et al (2011) observe that raw effluent from nearby Belem is present as is commercial fishing. There is potential for much human impact on this species but is hard to assess without more fieldwork.

  • Wilkinson, M. and Nussbaum, R.A. (1997). ''Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae).'' Biological Journal of the Linnean Society, 62, 39-109.
  • Wilkinson, M., Sebben, A., Schwartz, E.N.F., and Schwartz, C.A. (1998). ''The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil.'' Journal of Natural History, 32, 617-627.
  • Hoogmoed, M.S., Maciel, A.O., and Coragem, J.T. (2011). ''Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia.'' Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais, 6(3), 241-262.
Creative Commons Attribution 3.0 (CC BY 3.0)

© AmphibiaWeb © 2000-2011 The Regents of the University of California

Source: AmphibiaWeb

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Management

Conservation Actions

Conservation Actions
It is not known from any protected areas.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Relevance to Humans and Ecosystems

Risks

Relation to Humans

Unknown. The reclusive nature of caecilians results in little direct interaction with humans.

  • Wilkinson, M. and Nussbaum, R.A. (1997). ''Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae).'' Biological Journal of the Linnean Society, 62, 39-109.
  • Wilkinson, M., Sebben, A., Schwartz, E.N.F., and Schwartz, C.A. (1998). ''The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil.'' Journal of Natural History, 32, 617-627.
  • Hoogmoed, M.S., Maciel, A.O., and Coragem, J.T. (2011). ''Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia.'' Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais, 6(3), 241-262.
Creative Commons Attribution 3.0 (CC BY 3.0)

© AmphibiaWeb © 2000-2011 The Regents of the University of California

Source: AmphibiaWeb

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Atretochoana

Atretochoana eiselti is a species of caecilian known only from two preserved specimens until its 2011 rediscovery in Brazil. Until 1998, it was known only from the type specimen in the Naturhistorisches Museum, Vienna.[2] Originally placed in the genus Typhlonectes in 1968, it was reclassified into its own monotypic genus in 1996. It was also found to be more closely related to the genus Potomotyphlus than Typholonectes.[3] The species is the largest of the few known tetrapods, and one of two caecilians, to lack lungs, the other being Caecilita iwokramae.

Description[edit]

A. eiselti is the largest tetrapod to lack lungs, double the size of the next largest.[4] Caecilians such as Atretochoana are limbless amphibians with snake-like bodies, marked with rings like those of earthworms.[5] It has significant morphological differences from other caecilians, even the genera most closely related to it, even though those genera are aquatic.[3] The skull is very different from those of other caecilians, giving the animal a broad, flat head.[4] Its nostrils are sealed,[3] and it has an enlarged mouth with a mobile cheek.[6] Its body has a fleshy dorsal fin.[4]

Most caecilians have a well-developed right lung and a relictual left lung. Some, such as Atretochoana's relatives, have two well-developed lungs. Atretochoana, however, entirely lacks lungs, and has a number of other features associated with lunglessness, including sealed choanae, and an absence of pulmonary arteries.[7] Its skin is filled with capillaries that penetrate the epidermis, allowing gas exchange. Its skull shows evidence of muscles not found in any other organism.[6] The Vienna specimen of Atretochoana is a large caecilian at a length of 72.5 cm (28.5 in),[7] while the Brasília specimen is larger still at 80.5 cm (31.7 in).[8] By comparison, caecilians range in length from 11 to 160 cm (4.3 to 63.0 in).[7]

History[edit]

The specimen in the Vienna museum was known only to have originated from somewhere in South America, at least before 1945, most likely in the 19th century.[9] Its lack of lungs was not known at this time, and the specimen was assigned to the species Typhlonectes compressicauda.[10] The Vienna specimen was the holotype for this species when it was first described by Edward Harrison Taylor in his 1968 monograph Caecilians of the World. He named it Typhlonectes eiselti, in honour of Viennese herpetologist Josef Eiselt.[11] Taylor considered it to be similar to the aquatic caecilians of the genus Typhlonectes and Potomotyphlus, and placed it in the former genus, taking much note only of its large size and high number of splenial teeth.[10]

Taylor did not inform the curators of the Naturhistorisches Museum that he designated the specimen a holotype, so it was not mentioned in the museum's catalogue of type specimens, and was placed beneath glass in a public display. There, it was noticed by the visiting English herpetologist Mark Wilkinson, who then borrowed the specimen to examine it with his American colleague Ronald A. Nussbaum. Examination of the specimen showed it to have a number of unusual features, including the large number of splenial teeth observed by Taylor, but most unusually, closed choanae, which showed it could not fill any lungs it might have.[10]

Because of these and other distinctive features, Nussbaum and Wilkinson gave this species its own genus when they reported on the results of their research in a 1995 issue of the Proceedings of the Royal Society B. The name they gave this genus was Atretochoana, from the Greek word atretos, meaning "imperforate", and the Greek word choana, referring to a funnel or tube.[7] Nussbaum and Wilkinson published further studies in 1997 describing in detail the caecilian's anatomy and morphology. In 1998, they discovered the second specimen in the Universidade de Brasilia,[12] although the origin of this specimen was also unknown.[1] In 1999, they determined Atretochoana was a sister taxon of Potomotyphlus, and in 2011, grouped it in the Typhlonectidae family.[12] Both of these specimens are mature females.[9]

Biology[edit]

Most caecilians are burrowers, but some, including Atretochoana's relatives, are largely aquatic.[10] Atretochoana is thought to be aquatic since its relatives and lungless salamanders, some of the few other lungless tetrapods, are,[11] though the only other known species of lungless caecilian, Caecilita iwokramae, is terrestrial.[13] It was postulated to inhabit fast-flowing water.[6]

Due to the lack of information, it is classified as "Data Deficient" by the International Union for Conservation of Nature. It is thought to be uncommon, with a limited distribution.[2] It is likely a predator or scavenger,[6] and is thought to be viviparous.[1]

In June 2011, an amphibian was photographed near Praia de Marahú on Mosqueiro Island (near Belém, Brazil) that appeared to be A. eiselti, but was not positively identified. In 2011, six individuals were found in the Madeira River. Neither have cold, fast-flowing water, as was originally thought. As there is less oxygen in warmer water, this makes its lack of lungs even more unusual, and the question of how it breathes has not yet been resolved.[12][14][15]

References[edit]

  1. ^ a b c Wilkinson, Mark; Measey, John; Wake, Marvalee (2004). "Atretochoana eiselti". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. 
  2. ^ a b "Distribution and conservation". Natural History Museum. Retrieved 22 February 2012. 
  3. ^ a b c "Taxonomy". Natural History Museum. Retrieved 22 February 2012. 
  4. ^ a b c "Atretochoana eiselti". Natural History Museum. Retrieved 22 February 2012. 
  5. ^ Naskrecki, Piotr (2005). The Smaller Majority. London: Belknap. pp. 46–47. ISBN 978-0-647-02562-8. 
  6. ^ a b c d "Biology". Natural History Museum. Retrieved 22 February 2012. 
  7. ^ a b c d Nussbaum, Ronald A.; Wilkinson, Mark (1995). "A New Genus of Lungless Tetrapod: A Radically Divergent Caecilian (Amphibia: Gymnophiona)". Proceedings of the Royal Society B 261 (1362): 331–339. doi:10.1098/rspb.1995.0155. 
  8. ^ Wilkinson, M.; Sebben, A.; Schwartz, E.N.F.; Schwartz, C.A. (1998). "The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil". Journal of Natural History 32 (4): 617–627. doi:10.1516/Q417-21HR-6615-7217. 
  9. ^ a b Knapp, Michelle (3 February 2003). "Atretochoana eiselti". Information on amphibian biology and conservation. AmphibiaWeb. Retrieved 21 January 2010. 
  10. ^ a b c d Nussbaum, Ronald A.; Wilkinson, Mark (1997). "Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae)". Biological Journal of the Linnean Society 62 (1): 39–109. doi:10.1111/j.1095-8312.1997.tb01616.x. 
  11. ^ a b Himstedt, Werner (2000). "Lungless Tetradodes". In Hofrichter, Robert. Amphibians: The World of Frogs, Toads, Salamanders and Newts. New York: Firefly. p. 81. ISBN 1-55209-541-X. 
  12. ^ a b c Hoogmoed, Marinus Steven; Coragem, Juliano Tupan (2011). "Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia". Boletim do Museu Paraense Emílio Goeldi : Ciências Naturais 6 (3): 241–262. ISSN 1981-8114. Retrieved 22 February 2011. 
  13. ^ Wake, Marvalee H.; Donnelly, Maureen A. (22 March 2010). "A new lungless caecilian (Amphibia: Gymnophiona) from Guyana". Proceedings of the Royal Society B 227 (1683): 915–922. doi:10.1098/rspb.2009.1662. 
  14. ^ Ximenes, Marcela (31 July 2012). "Anfíbio com formato de cobra é descoberto no Rio Madeira, em RO" [Snake-shaped amphibian found in the Rio Madeira, RO] (in Portuguese). Globo. Archived from the original on 1 August 2012. Retrieved 1 August 2012. 
  15. ^ Butler, Rhett (2 August 2012). "'Penis snake' discovered in Brazil is actually a rare species of amphibian". Mongabay. Retrieved 11 August 2013. 
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!