Atretochoana eiselti
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Atretochoana eiselti |
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| Nussbaum & Wilkinson , 1995 | ||||||||||||
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| ( Taylor , 1968) |
Atretochoana eiselti is alungless sneak amphibian livingin rivers of the Amazon region . This sneak amphibian is the only species of the monotypical genus Atretochoana . Until the discovery of the also lungless species Microcaecilia iwokramae in 2009, Atretochoana eiselti was the only lungless sneak amphibian.
The generic name Atretochoana , from the Greek atretos for imperforate and choane for funnel or tube , refers to the closed choane . The Artzusatz eiselti honors the Vienna herpetologists Josef Eiselt ,
features
Nussbaum and Wilkinson described the genus as Typhlonectidae with choans closed by the overgrown valve flaps. Atretochoana are lungs and have no pulmonary blood vessels. The jaws are connected postcranially , behind the back of the head and can therefore be opened wide. The stirrup is greatly elongated and directed backwards, including an unusual cranial muscle that connects the cheeks with the stapes. Nussbaum and Wilkinson interpret the radically reshaped skull as an indication of evolutionary change towards larger prey by abandoning the function of supplying the lungs.
The few specimens described so far were between 72 centimeters and one meter long, weighed 140 to 840 grams and are lungless skin breathers . Atretochoana eiselti is thus the largest lungsless terrestrial vertebrate . The body is serpentine, like other sneaking amphibians it has no limbs. A low, fin-like fold of skin runs over the entire back, which, however, in the second one by Wilkinson et al. examined specimen, probably because of a poor or possibly sick condition of the animal, was significantly less pronounced. The holotype also showed some loose skin on the abdomen in front of the cloacal disc , which Nussbaum and Wilkinson saw as an indication of a short "ventral fin". Outside the water, Hoogmoed describes this as only recognizable as a low ridge, but in the water he could clearly observe that Atretochoana eiselti moved slowly swimming through undulating movement of the dorsal and lower ventral fin. In the specimens described, 100 to about 110 complete or partial skin folds ( annuli ) were counted.
The head is long, broad and flat, with a protruding bulbous snout. The eyes are towards the back and deepened, there are large, forward-facing nostrils. The mouth is covered with many teeth. The tentacle openings are small and are closer to the nostrils than to the eyes. The tentacles are presumably not extensible like in other aquatic species. The cloak disc is oval .
The lively coloration of specimens from the Rio Madeira , based on slide recordings, is as follows: The top of the head and the back are brownish gray to bluish gray, the color on the abdomen is a little lighter. The lower lip is colored like the back, the throat dirty white and much lighter than the lower lip. The cloacal disc is pink in the center and surrounded by a greyish white area.
Way of life
Atretochoana eiselti lives aquatically. Otherwise, little is known about this rare species, and data about its habitat are partly contradicting. The species is diurnal and has been observed to be a good swimmer. Nothing is known about their diet, the stomachs of the specimens examined were empty or the contents indefinable. What is certain is that the species has no lungs. It is unclear exactly how oxygen uptake in water works, the only way seems to be through the skin. Possibly the skin folds enlarge the skin surface and facilitate the oxygen supply, whereby the ratio of skin surface to body volume is unfavorable in such a large animal, other lungless animals are much smaller. Wilkinson and Nussbaum argued that the absence of the lungs and gas exchange through the skin correlated with life in cold, montane, and fast-flowing rivers. Hoogmoed, et al. discovered, however, that the species occurs in warm (24–30 ° C), fast-flowing lowland rivers.
Occurrence
The few found specimens come from two far apart areas of the Brazilian Amazon basin. On the one hand in the estuary (Mosqueiro island and Baía de Marajó, Belém ) and on the other hand in the Rio Madeira , near the Bolivian border (Cachoeira Santo Antônio).
Taxonomy
Atretochoana in 1968 by Edward Harrison Taylor Typhlonectes eiselti based on an older copy of the Natural History Museum in Vienna firstdescribed . The description was unusually short, the shortest of Taylor's 39 first descriptions and one of the few without illustrations . It was not mentioned that the animal from South America had no lungs. In 1995, Nussbaum and Wilkinson examined the type specimen more closely, found that it was lungless, and placed the species in its own, monotypical genus Atretochoana .
Individual evidence
- ^ MH Wake, MA Donnelly: A new lungless caecilian (Amphibia: Gymnophiona) from Guyana. In: Proceedings. Biological sciences. Volume 277, number 1683, March 2010, pp. 915-922, doi: 10.1098 / rspb.2009.1662 , PMID 19923127 , PMC 2842721 (free full text).
- ^ A b RA Nussbaum, M. Wilkinson: A New Genus of Lungless Tetrapod: A Radically Divergent Caecilian (Amphibia: Gymnophiona). In: Proceedings of the Royal Society B: Biological Sciences. 261, 1995, p. 331, doi: 10.1098 / rspb.1995.0155 . ( Online )
- ^ F. Tiedemann: Real Councilor Dr. Josef Eiselt on his 80th birthday. 1992 in: HERPETOZOA 5 (3/4), pp. 83-90. ( Online )
- ↑ a b c d e f g h Marinus Steven Hoogmoed, Adriano Oliveira Maciel, Juliano Tupan Coragem: Discovery of the largest lungless tetrapod, Atretochoana eiselti (Taylor, 1968) (Amphibia: Gymnophiona: Typhlonectidae), in its natural habitat in Brazilian Amazonia . 2011, in: Boletim do Museu Paraense Emílio Goeldi. Ciências Naturais 6 (3), pp. 241-262. ( Online )
- ↑ a b c d Mark Wilkinson, Ronald A. Nussbaum: Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae). In: Biological Journal of the Linnean Society 62, No. 1, 1997, pp. 39-109, doi: 10.1111 / j.1095-8312.1997.tb01616.x .
- ^ Mark Wilkinson, Ronald A. Nussbaum: Evolutionary relationships of the lungless caecilian Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae). In: Zoological Journal of the Linnean Society 126, No. 2, 1999, pp. 191-223.
- ↑ a b Mark Wilkinson et al. : The largest lungless tetrapod: report on a second specimen of Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae) from Brazil. In: JOURNAL OF NATURAL HISTORY , 1998, 32, pp. 617-627. ( Online )