Osteology and Intraspecific Variation of Leptodactylus podicipinus (Anura: Leptodactylidae), with Comments on the Relationship between Osteology and Reproductive Modes

Knowledge of the osteology of species of the Leptodactylus melanonotus group is limited. Nevertheless, osteological characters are useful to diagnose species to, to propose phylogenetic relationships, to understand patterns of morphological evolution, and to predict biological function associated with morphology. Here, we describe the whole osteology of Leptodactylus podicipinus; we have special interest in osteological and morphometric characters whose interpopulational and intersexual differences can be related with fossorial habits. Individuals from the Pantanal, Brazil, were compared with L. podicipinus from northern Argentina and central and southern Paraguay by analyzing morphometric and osteological characters. The quantitative data revealed sexual dimorphism in tarsus length in the specimens from the Pantanal. The observed interpopulation osteological differences could not be associated with burrowing habits. Osteologically, L. podicipinus is intermediate between the members of the Leptodactylus fuscus group, which is more specialized for digging, and the generalized L. melanonotus, Leptodactylus latrans, and Leptodactylus pentadactylus groups.