Temporal patterns of thyroid gland maturation and skin metamorphosis in terrestrial indirect-developing de Villiers moss frogs (Arthroleptella villiersi Hewitt, 1935)

Background

Anurans show diverse life histories ranging from the ancestral aquatic indirect development to derived terrestrial developmental modes that often correlate with the reduction of larval characters. The de Villiers moss frog Arthroleptella villiersi Hewitt, 1935 (Pyxicephalidae) exhibits terrestrial indirect development, hatching as endotrophic tadpoles that undergo metamorphosis within the jelly nest. We investigated the timing and histology of skin and thyroid gland development of A. villiersi to test whether metamorphic rearrangements were conserved and to assess the role of heterochrony in terrestrialization of anuran life histories.