A tale of a tail: variation during the early ontogeny of Haddadus binotatus (Brachycephaloidea: Craugastoridae) as compared to other direct-developers

GOLDBERG, J.; VERA CANDIOTI, MF

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Lugar: Salt Lake City; Año: 2015 vol. 49

0022-1511

The New World direct-developing frogs (Brachycephaloidea = Terrarana) comprise nearly a thousand species that share direct development among other putative synapomorphies, yet embryonic development in this group has been thoroughly described in only about 20 species. Here we describe the early ontogeny of the craugastorid Haddadus binotatus, making special emphasis on tail structure and development, and its differences and similarities with that of other terraranans. The morphological changes during embryonic development of H. binotatus and those of other Neotropical direct-developing species are alike, with some variation including the absence of external gills, timing of limb differentiation, and tail configuration. The tail with a rotated core axis and lateral and asymmetric fins that cover the posterior half of the embryo represents an outstanding case of developmental repatterning. We present some interpretations of the evolution of the tail and its three major aspects, the rotation of the core axis, and the origin and extensions of the fins, and pinpoint that those mechanisms underlying fin development should be fairly plastic, allowing the ontogenetic and evolutionary variation within the Brachycephaloidea clade.