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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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
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.
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Population

Population
It is known only from two specimens.

Population Trend
Unknown
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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.
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Threats

Major Threats
There is no information on threats to this species.
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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.
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Management

Conservation Actions

Conservation Actions
It is not known from any protected areas.
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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.
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