title: Caecilita Wake & Donnelly, 2010 (Amphibia: Gymnophiona) is not lungless: implications for taxonomy and for understanding the evolution of lunglessness .
abstract: According to current understanding, five lineages of amphibians, but no other tetrapods, are secondarily lungless and are believed to rely exclusively on cutaneous gas exchange. One explanation of the evolutionary loss of lungs interprets lunglessness as an adaptation to reduce buoyancy in fast-flowing aquatic environments, reasoning that excessive buoyancy in such an environment would cause organisms being swept away. While not uncontroversial, this hypothesis provides a plausible potential explanation of the evolution of lunglessness in four of the five lungless amphibian lineages. The exception is the most recently reported lungless lineage, the newly described Guyanan caecilian genus and species Caecilita iwokramae Wake & Donnelly, 2010, which is inconsistent with the reduced disadvantageous buoyancy hypothesis by virtue of it seemingly being terrestrial and having a terrestrial ancestry. Re-examination of the previously only known specimen of C. iwokramae and of recently collected additional material reveal that this species possesses a reasonably well-developed right lung and is a species of the pre-existing caecilian genus Microcaecilia Taylor, 1968. We therefore place Caecilita in the synonymy of Microcaecilia, and re-evaluate the plausibility of the reduced disadvantageous buoyancy hypothesis as a general explanation of the evolution of lunglessness.
authors.affiliation: Department of Life Sciences, The Natural History Museum, London, SW7 5BD, UK; Email: m.wilkinson@nhm.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Wilkinson
authors.affiliation: Biology Department, Amphibian Evolution Lab, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium and Department of Vertebrates, Royal Belgian Institute of Natural Sciences, 29 rue Vautier, B-1000 Brussels, Belgium; Email: unknown.
authors.forename: Philippe J R
authors.initials: PJ
authors.lastname: Kok
authors.affiliation: Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK; Email: unknown.
authors.forename: Farah
authors.initials: F
authors.lastname: Ahmed
authors.affiliation: Department of Life Sciences, The Natural History Museum, London, SW7 5BD, UK; Email: unknown.
authors.forename: David J
authors.initials: DJ
authors.lastname: Gower
mesh_terms: D000663:Amphibians / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics; D000818:Animals; D005075:Biological Evolution; D008168:Lung / Q000033:anatomy & histology; D008297:Male