Life history and reproduction of the neotropical caecilian Siphonops annulatus (Amphibia, Gymnophiona, Siphonopidae), with special emphasis on parental care

Due to their mainly fossorial way of life, caecilian amphibians are the least known order of terrestrial vertebrates. Here, we present new observations on the natural history and reproductive biology of the neotropical oviparous, siphonopid caecilian Siphonops annulatus from a long-term study of this species in the field and in captivity. In the studied population, mating occurs between the end of August and beginning of October, and oviposition between November and December, when rainfall peaks. Egg hatching occurs between the end of December and beginning of January. The complete cycle of maternal care, from oviposition to independent, self-sufficient offspring lasts about 3 months. After eclosion, the altricial young feed on the mother's specially modified skin (maternal dermatophagy) and are also supplied by a fluid released from coming from the maternal cloaca. Also presented are observations on the burrows, feeding and social behaviour of S. annulatus.

Metabolic and endocrine changes during the reproductive cycle of dermatophagic caecilians in captivity.

The amphibian order Gymnophiona is poorly known, and studies about their reproduction are mainly comparative and descriptive, focusing on the structure of testes, ovaries and oviducts. However, to understand the reproductive processes, including those of the oviparous dermatophagic species, it is important to know the dynamics of storage and mobilization of energetic substrates to gonads and skin during the reproductive cycle of males and females, as well as the endocrine control associated. For the present study, total lipids and proteins were measured during the annual cycle in the plasma, liver, muscle, testes, ovaries and skin of Siphonops annulatus in captivity. Plasma levels of gonadal steroids (estradiol, testosterone and progesterone) were quantified by radioimmunoassay. Histological analyses of ovaries and testes were performed to classify the maturation stages of the animals during the reproductive cycle. Gonadal maturation in males and females of S. annulatus was accompanied by metabolic changes in reserve tissues, which supported gonadal development and prepared the females' epidermis for skin feeding by the offspring. Even in confinement conditions, females and males synchronized the reproductive period. However, due to the absence of environmental cues in captivity inadequate levels of the hormones responsible for gamete release were triggered, leading to a lack of reproductive success.