Morphology and posthatching ontogeny of the autopodial skeleton of Bolitoglossa nicefori (Caudata: Plethodontidae).

Webbed foot morphology is a highly homoplastic character in species of Bolitoglossa and has been assumed to be pedomorphic. This study examines the morphology and posthatching ontogeny of the autopodial skeleton of Bolitoglossa nicefori and compares the descriptive and morphometric results with other species of the genus. We show that the autopodial morphology of B. nicefori coincides with the generalized pattern of the genus; webbed foot morphology is produced by pedomorphosis that affect the phalange length of the digits, resulting in a synchronized growth of digits (length and ossification rates) and the fleshy web. Although the webbed foot morphology of B. nicefori might be explained by the pervasive pedomorphic developmental trend observed in the genus, the large degree of variation encountered in the morphology of the distal phalanges indicates that the pedomorphic processes acting in this species are neither a simple truncation of the autopodial developmental program during early posthatching development nor a global process acting over the whole body plan. Instead, this morphological pattern is probably a result of the modular nature of limb development.