Survey of morphological and heterochronical variations during early ontogeny in six families of Leptodactyliformes (Anura: Hyloides)

GROSSO J.; VERA CANDIOTI J.; BALDO, D.; BARRASSO, D.; NATALE G.S.; NOGUEIRA COSTA, P.; BARRIONUEVO, S.

Washington DC

Congreso; International Congress of Vertebrate Morphology; 2016

The early ontogeny in anurans includes the occurrence of transient, exclusively embryonic structures, plus the initial stages of development of larval features. We compared developmental series of 13 species belonging to six families of the clade Leptodactyliformes, in order to record morphological and heterochronical changes among them. Main variations concern the size, pigmentation and dorsal curvature of embryos at tailbud stage, the morphogenetic pattern of adhesive (cement) glands, the number and arrangement of external gill pairs, and the development of larval mouthparts. Tailbud embryos of Telmatobius oxycephalus (Telmatobiidae), Limnomedusa macroglossa (Alsodidae), and ceratophryid Ceratophrys cranwelli, C. ornata, and Chacophrys pierotti are well-pigmented and have no dorsal curvature. Conversely, Batrachyla leptopus (Batrachylidae) and six species of Odontophrynidae have pigmented but kyphotic embryos. Embryos of Cycloramphus brasiliensis (Cycloramphidae) lack pigmentation completely. Three different adhesive gland types occur: type A in Ceratophryidae and L. macroglossa, type C in Odontophrynidae and B. leptopus, and type B in T. oxycephalus, being this latter typical of unrelated bufonids. The adhesive glands are absent in C. brasiliensis. Regarding external gills, two pairs occur in Odontophrynidae, L. macroglossa, and C. brasiliensis¸ and a third pair develops in Ceratophryidae, T. oxycephalus, and B. leptopus, in this latter case poorly developed. Ontogeny of the oral disc is similar in all species with labial tooth row formula 2/3, whereas Ceratophrys spp. differ in development of supernumerary tooth rows. The surveyed variations appear to be related to phylogenetical rather than ecological aspects, and some patterns will likely be proven diagnostic of some clades (e.g., type B adhesive glands in Telmatobius, three gill pairs in ceratophryids). On the other hand, the unusual set of features of the exotrophic, semiterrestrial C. brasiliensis specimens (large yolk provision, and lack of pigmentation and adhesive glands) are typical of endotrophic embryos, and possibly conserved within the genus.