Skeleton in the closet: hidden diversity in patterns of cranial and postcranial ontogeny in Neotropical direct-developing frogs (Anura: Brachycephaloidea)

VERA CANDIOTI, F; GOLDBERG, J.; AKMENTINS, M.; NOGUEIRA COSTA, P; GOULART TAUCCE, P; POMBAL, J JR

ORGANISMS DIVERSITY & EVOLUTION

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2020

1439-6092

Direct development implies transformations with respect to the anuran biphasic life cycle, including changes in embryonicanatomy. In the clade Brachycephaloidea, skeletal ontogeny is known in Eleutherodactylus coqui of the basal familyEleutherodactylidae. In this work, we study it in four species representing the two other families in the group. We worked withdevelopmental series of Oreobates barituensis, Haddadus binotatus, Ischnocnema henselii, and Brachycephalus ephippium.Specimens were prepared following protocols of clearing and staining and histology. In the cranium, results show an overallshared pattern that, as summarized for E. coqui, combines a partial recapitulation of aspects of the ancestral biphasic ontogenywith a profound remodeling that includes lost/novel structures and heterochronic shifts of developmental events. Among thesetransformations are the absence of suprarostrals and trabecular horns and the precocious ossification of jaw and suspensorium. Inaddition, each lineage shows particular features such that skull ontogeny varies interspecifically. In turn, the morphogenesis ofthe axial and appendicular skeleton is highly conserved, with main variations including the extent of ossification at hatching.Along with some external features such as the egg tooth and the enveloping tail with transversely arranged fins, an ossificationsequence with extremely accelerated ossification of jaws and suspensorium could be distinctive of Brachycephaloidea.