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	Conservation Status (definitions)
IUCN (Red List) Status
CITES	No CITES Listing
Other International Status	None
National Status	None
Regional Status	None

Description
This species is the smallest New World caecilian and is known only from the holotype, an adult female of 112 mm total length. Unlike all other caecilians, it has closed nostrils that are covered with skin. It is also the first lungless terrestrial caecilian to be described (the other known lungless caecilian, Atretochoana eiselti, is aquatic).

Holotype: The type specimen (CSBD HA 1500, Center for Biological Diversity, Univ. of Guyana) is an adult female discovered during a survey of the vertebrate fauna in Iwokrama Forest in central Guyana (Donnelly et al. 2005).

Wake and Donnelly (2009) placed C. iwokramae in the family Caeciliidae based on skeletal and soft tissue features. However, the authors distinguished this specimen from other genera of the Caeciliidae and placed it in a new genus Caecilita.

Features shared with the family Caeciliidae: The genus Caecilita is placed in the family Caeciliidae due to its fused nasal and premaxilla, loss or fusion of septomaxilla, prefrontal, postfrontal, and pterygoid. It is also united with other members of this family by the lack of a tail, subdivision of some primary annuli, and presence of scales. Features of the heart include a truncus arteriosus formed by fused aortic arches and an undivided atrium (externally) (Wake and Donnelly 2009).

Features that distinguish the new genus Caecilita from other caeciliid genera: Caecilita iwokramae can be distinguished from Microcaecilia on the basis of its covered eye, but open orbit and the presence of a small keel on the most posterior annulus. The new species is not placed in the genus Caecilia based on the dorsally unexposed mesethmoid, the lack of inner mandibular teeth, the lack of narial plugs, the location of the tentacle, and the presence of the keel. Caecilita iwokramae is not a member of Oscaecilia based on several traits above and the placement of the vomeropalatine tooth rows. The specimen can be distinguished from Parvicaecilia due to the presence of the terminal keel and long premaxillopalatine tooth rows, and from Brasilotyphlus due to the lack of a diastema between the palatine and vomerine dentition as well as the open orbit. Wake and Donnelly (2009) distinguish Caecilita iwokramae from Luetkenotyphlus, Siphonops, Mimosiphonops, Gymnopis, and Dermophis based on combinations of the features listed above. The specimen can also be distinguished from Old World members of the Caeciliidae based on combinations of these features (Wake and Donnelly 2009).

Caecilita iwokramae is the smallest described caecilian of the New World (112 mm total length). The holotype specimen (the only one known so far) is 3.5 mm wide over most of the body posterior to the head. The small size of the animal results in a low surface area to volume ratio of about 1.16, which may facilitate cutaneous respiration. The other lungless caecilian, Atretochoana eiselti (Gymnophiona: Typhlonectidae), is significantly larger than C. iwokramae (all specimens found have all been over 725 mm TL). Caecilita iwokramae can be distinguished from all described caecilians (including A. eiselti) by its lack of open external nares. Similar to A. eiselti, its internal nares (choanae) are covered by the oral mucosa. Secondarily covered internal nares have only been found in C. iwokramae (Wake and Donnelly 2009) and A. eiselti (Wilson and Nussbaum 1997) but no other tetrapods. Caecilita iwokramae has eyes and an open orbit, but a thick layer of skin covers the eyes. It lacks a true tail. The specimen has 102 primary annuli, with six complete secondary annuli and three incomplete annuli ventrally. A total of 107 vertebrae are present, with no ribs present on the three posterior vertebrae. The tentacles can be seen as small spherical bulges near the covered eyes. Caecilita iwokramae has a small keel in its terminal annulus (Wake and Donnelly 2009).

Viscera: Lungs are absent in C. iwokramae. The animal’s heart has no superficially visible distinctive features, but there is a loss of pulmonary circulation. The ovaries are approximately 10 mm long. The left ovary contains four large ova (1.2 mm diameter) and the right contains three ova. Wake and Donnelly (2009) also found several previtellogenic ova.

Skin: The epidermis is thin with a keratinized outermost layer. The dermis is deeper and has capillaries near to its surface as well as mucous and granular glands. Wake and Donnelly (2009) did not consider the skin to be hypervascularized, which commonly occurs in animals that rely on cutaneous respiration (Bennett and Wake 1974; Hutchison et al 1976). This is in contrast to A. eiselti, which does display skin hypervascularization (Nussbaum and Wilkinson 1995). There are some scattered scales present (Wake and Donnelly 2009).

Tongue: The tongue is highly vascularized, possibly serving a respiratory function (Wake and Donnelly 2009).

Color: In preservative it is light yellow-brown on the ventral and dorsal aspects with mottled dark pigmentation around light skin glands. The throat is cream colored. The annuli become darker posteriorly (Wake and Donnelly 2009).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guyana

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This species occurs in Guyana. It is known only from the type locality, the Iwokrama Forest near ‘Top Camp’ (4°20'N, 58°48'W, about 1,000 m asl) (Wake and Donnelly 2009). Iwokrama Forest is lowland tropical forest, with a warm tropical climate (Donnelly et al. 2005). The habitat at the type locality consists of low, mixed scrub forest (Donnelly et al. 2005).

Life History, Abundance, Activity, and Special Behaviors
Caecilita iwokramae is terrestrial, in contrast to the other known species of lungless caecilian, Atretochoana eiselti, which is aquatic. C. iwokramae is likely insectivorous, judging by the unidentified insect remains found in its stomach. Since C. iwokramae has a sealed nasal cavity, Wake and Donnelly (2009) hypothesize that olfactory chemosensory activity is vomeronasal and achieved mainly through the tentacle. It is one of only two caecilian species that are miniaturized, the other being Idiocranium russell (Maddin 2011).

Trends and Threats
This species is known only from the holotype, and nothing is known about its population status.

Comments
Species authority: Wake and Donnelly (2009).

Caecilita likely evolved from a terrestrial caecilian. Comparison to other lungless tetrapods casts doubt on several hypotheses concerning the selective pressures involved in lung loss (Wake and Donnelly 2009; Wilkinson and Nussbaum 1997). For instance, assuming a terrestrial ancestor (all of Caeciliidae is terrestrial), the loss of lungs in Caecilita does not support the hypothesis that lungs have been lost in response to selection for lower buoyancy in fast-moving mountain streams (Wilder and Dunn 1920). With some exceptions (including Atretochoana eiselti), lunglessness has so far been documented in small species with a high surface area to volume ratio (Bickford et al 2008; Wake and Donnelly 2009). The efficient cutaneous and buccal respiration found in small amphibians may enable the evolution of lung loss (Wake and Donnelly 2009). However, in the face of few consistently shared ecological and morphological traits uniting lungless amphibians it is very possible that divergent selective pressures brought about independent instances of lung loss.

References
 

Bennett, A. F., and Wake, M. H. (1974). ''Metabolic correlates of activity in the caecilian Geotrypetes seraphini.'' Copeia, 1974(3), 764-769.  

Bickford, D., Iskandar, D., and Barlian, A. (2008). ''A lungless frog discovered on Borneo.'' Current Biology, 18, R374-R375.  

Donnelly, M. A., Chen, M. H., and Watkins, G. G. (2005). ''The Iwokrama Herpetofauna: An exploration of diversity in a Guyanan rainforest.'' Ecology and Evolution in the Tropics: a Herpetological Perspective. M. A. Donnelly, B. I. Crother, C. Guyer, M. H. Wake, and M. E. White, eds., The University of Chicago Press, Chicago.  

Hutchison, V. H., Haines, H. B., and Engbretson, G. (1976). ''Aquatic life at high altitude: respiratory adaptations in the Lake Titicaca frog, Telmatobius culeus.'' Respiration Physiology, 27, 115-129.  

Maddin, H. C. (2011). ''Deciphering morphological variation in the braincase of caecilian amphibians (gymnophiona).'' Journal of Morphology, 272, 850-871.  

Nussbaum, R. A. and Wilkinson, M. (1989). ''On the classification and phylogeny of caecilians (Amphibia: Gymnophiona), a critical review.'' Herpetological Monographs, (3), 1-42.  

Nussbaum, R. A., and Wilkinson, M. (1995). ''A new genus of lungless tetrapod: a radically divergent caecilian (Amphibia: Gymnophiona).'' Proceedings of the Royal Society B, 261, 331-335.  

Wake, M. H. and Donnelly, M. A. (2009). ''A new lungless caecilian (Amphibia: Gymnophiona) from Guyana.'' Proceedings of the Royal Society B, published online 18 November 2009, doi: 10.1098/rspb.2009.1662.  

Wake, M. H., Parra-Olea, G., and Sheen, J. P.-Y. (2005). ''Biogeography and molecular phylogeny of certain New World caecilians.'' Ecology and Evolution in the Tropics: a Herpetological Perspective. M. A. Donnelly, B. I. Crother, C. Guyer, M. H. Wake, and M. E. White, eds., The University of Chicago Press, Chicago.  

Wilder, I. W., and Dunn, E. R. (1920). ''The correlation of lunglessness in salamanders with a mountain brook habitat.'' Copeia, 1920, 63-68.  

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., and Nussbaum, R. A. (1999). ''Evolutionary relationships of the lungless caecilian Atretochoana eiselti (Amphibia: Gymnophiona: Typhlonectidae).'' Zoological Journal of the Linnean Society, 126, 191-223.

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