Heterochronic changes during embryonic development of neotropical foam nesting frogs (genus Leptodactylus)

GROSSO, J; VERA CANDIOTI, MF; BALDO, D

ZOOLOGISCHER ANZEIGER

ELSEVIER GMBH

Año: 2017 vol. 266 p. 35 - 49

0044-5231

At least five different reproductive modes were reported in the neotropical frog genus Leptodactylus, all ofthem involving the building of foam nests. We analyzed the early ontogeny of five species of the L. fuscusgroup building terrestrial chambers where eggs are deposited, and of two species of the L. latrans groupconstructing a floating nest over the surface of lentic waters. The ontogenetic period described hereinincludes the occurrence of exclusively embryonic structures and the initial stages of development of larvalfeatures. In a likely relation to ecological aspects of oviposition and developmental mode, embryosof these two groups differ in several features. Embryos of the L. fuscus group were mainly pigmentless,were large sized with an extensive yolk provision, showed a dorsal kyphosis and lacked adhesiveglands. Conversely, embryos of the L. latrans group were darkly pigmented, lacked a dorsal curvature,were comparatively smaller and less yolked, and showed adhesive glands in a peculiar type D morphogeneticpattern. Embryos of the L. latrans group had long, profusely branched, highly ciliated externalgills, which were arranged ventrally. The comparative analysis of developmental sequences revealed anearly emergence of hind limbs in Leptodactylus species relative to a reference leiuperine trajectory, anearlier differentiation of external gills in the species of the L. fuscus group, and an overall earlier developmentof mouthparts in embryos of the L. latrans group. Further analyses in a phylogenetic context areneeded to evaluate the ancestral reconstructions of the development sequence and detect evolutionaryrelevant heterochronies in the genus.