Lunglessness is rare in the Tetrapoda and previously recorded only in salamanders (Amphibia: Caudata). Here we report lunglessness in another group of tetrapods, the poorly known tropical caecilians (Amphibia: Gymnophiona). Typhlonectes eiselti is a lungless, aquatic caecilian from South America known only from the single holotype specimen, NMW 9144 (Vienna Museum of Natural History). At a total length of 725 mm, NMW 9144 is by far the largest known lungless tetrapod. It also has a startling array of other radically divergent morphological features, many unique, and some correlated with lunglessness including: sealed choanae (paired internal nostrils); complete absence of pulmonary blood vessels; a repatterned skull with post-occipital jaw articulation; and a novel cranial muscle associated with an elongate and redirected stapes. This remarkable combination of highly derived characters sets Typhlonectes eiselti apart from all other caecilians and places it on a novel evolutionary trajectory. A new genus is described to accommodate this form.
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.
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
Nussbaum, Ronald A.; Wilkinson, Mark. 1995. A New Genus of Lungless Tetrapod: A Radically Divergent Caecilian (Amphibia: Gymnophiona). Proceedings of the Royal Society of London Series B Biological Sciences. 261 (1362): 331–339. DOI:10.1098/rspb.1995.0155 .