Ichthyophis

Abstract: Caecilians (Amphibia: Gymnophiona) are elongate, limbless, burrowing or swimming animals. They are pan-tropical in distribution and, until recently, infrequently seen by collectors. The relationships of caecilians to other amphibians are enigmatic (Carroll and Currie 1975), and relationships among caecilian genera and species are poorly understood. The acquisition of the attenuate habitus has been accompanied by changes of suites of morphological features, including those of the reproductive system. Concomitantly, a number of aspects of the physiology and ecology of the group have adapted, so that features of the reproductive biology and life histories of caecilians provide considerable information of use in analyzing patterns of evolution.

Abstract: The remarkable diversity of reproductive modes, including levels of parental care that are extensive relative to those of the other major amphibian groups, makes the limbless tropical caecilians ideally suited for evolutionary reproductive studies Here we present key life history data for the oviparous caecilian Ichthyophis cf kohtaoensis We used non-invasive methods to analyse reproductive traits, seasonality of breeding and characteristics of oviposition sites in the field (Mekong valley, north-eastern Thailand) A correlation was established between reproductive activity and season, indicated by the age of egg clutches found in the field Eggs at early developmental stages were found at the beginning of the rainy season, those with well-developed embryos at the peak of the monsoon The body condition of females guarding younger clutches was superior to that of females with older clutches, indicative of a loss of energy reserves during the period of parental care Maternal total length correlated positively with the number of eggs as well as with the total length of newly hatched larvae The terrestrial oviposition sites of females were located close to temporary and permanent ponds, small brooks and rivers It is hoped that the study will, in addition to contributing to our understanding of the evolution of caecilian reproduction, provide a basis for further comparisons of reproductive strategies among amphibians and other terrestrial tetrapods © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83, 207–217

Abstract: SUMMARY In comparison with the other amphibian orders, the Anura (frogs) and Urodela (salamanders), knowledge of the visual system of the snake-like Gymnophiona (caecilians) is relatively sparse. Most caecilians are fossorial with, as far as is known any surface activity occurring mainly at night. They have relatively small, poorly developed eyes and might be expected to possess detectable changes in the spectral sensitivity of their visual pigments. Microspectrophotometry was used to determine the spectral sensitivities of the photoreceptors in three species of caecilian, Rhinatrema bivittatum, Geotrypetes seraphini and Typhlonectes natans . Only rod opsin visual pigment, which may be associated with scotopic (dim light) vision when accompanied by other ‘rod-specific’ components of the phototransduction cascade, was found to be present. Opsin sequences were obtained from the eyes of two species of caecilian, Ichthyophis cf. kohtaoensis and T. natans . These rod opsins were regenerated in vitro with 11- cis retinal to give pigments with spectral sensitivity peaks close to 500 nm. No evidence for cone photoreception, associated with diurnal and colour vision, was detected using molecular and physiological methods. Additionally, visual pigments are short-wavelength shifted in terms of the maximum absorption of light when compared with other amphibian lineages.